1. LECTURE 2. General Notions of Demography
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1. LECTURE 2. General Notions of Demography Ass. prof. PhD. Daina Lucia
2. Demography – Definition The word comes from Greek: demos = people and graphos = description. Demography is the science that studies the human population from the point of view of its dimensions, structure, evolution and general characteristics. Demography is the social science that studies the structure and the dynamics of phenomena and events associated with a certain population. 3. Importance Public health – studies the health state of the population Health state – is influenced by multiple factors (the structure of the population in terms of age-groups, sexes, occupations) The indicators used refer to the population in terms of different aspects (male or females, occupations, etc.); The actions aiming to improve the health state take into account the population’s characteristics; The primary source of information regarding the main demographic events (birth, death) is the doctor. 4. The Object of Demography The object of demography is the human population. Demography operates with three fundamental notions: - the demographic event – the observed case bearing demographic information (born alive, born dead, death, marriage, etc.) - the demographic phenomenon – the sum of demographic events characterizing a population during a certain period of time (birth rate, mortality) - the demographic indicator – the ratio measuring these phenomena. 5. The Theory of demographic transition 1904, Frank Notenstein 3 stages in the evolution of demographic phenomena The statistical stage – population statistics The biologization stage – the biological aspect of demographic events The sociologization stage– the social determinism in demographic events. I. State of Equilibrium – High natality, High mortality II. The population’s growth – Increased birth-rate, low mortality III. State of Equilibrium – Low birth-rate, constant mortality 6. Tendencies registered in Europe (I) - sharp decline in fertility and the decrease in the number of high rank children (III, IV, V, VI) si delay in the appearance of the first child - dropped marriage rate and the increase of the divorce rate, the consensual unions marking increased tendencies to replace marriages. Consequently, the number of children born out of wedlock increased. - the role of women in developed societies has become more important, as well as the level of their education. This phenomenon has favorable consequences upon children’s health. The number of unwanted children decreased and therefore the time dedicated to educating children increased. The more important role of women in society also influences the divorce rate, i.e. it contributes to the increase in the number of divorces.
1 7. Tendencies Registered in Europe (II) The efficiency of contraceptive methods has facilitated the appearance of consensual unions and the reduction of the number of unwanted children. the balance established between the number of children born alive and the number of deaths determines a low natural progress. As a consequence, the population is ageing. in 1985, the ratio between persons of 65 and over 65 was of 12%, while, in 2025, a ratio of 18% is expected. As a result, a modification of the dependence report can be observed. 8. Demographic components Population static: number, structure the distribution of the population Dynamics (population migration): a) natural = reproduction b) mechanic = movement generated by economic, social and political factors socio-professional mobility migration 9. Demographic indicators – Gross rates (I) Advantages: - easy to calculate - wide use at the international level - are not found in all the yearly books of WHO and the statistic breviaries Disadvantages - the level of the phenomena measured does not take into account the structural differences of the respective population- they can not be directly interpreted - no direct comparison can be made between them no. of events Rate = x 1000 the population no. 10. Demographic indicators – Specific rates Advantages: - are applicable to sub-groups of homogeneous population - are widely used in epidemiological studies - allow the comparison of sub-groups of the same type Disadvantages: - the totality of the population is disregarded no. of events in the U population Specific rate in terms of environments (U/R) = x 1000 the urban population 11. Demographic indicators – Standardized rates Advantages: - eliminate the influence of certain features of the population (sex, age group, etc.) upon the level of the indicator - ensure the achievement of the most correct comparisons among different populations Disadvantages: - they are calculated, artificial, fictive indicators;
2 - they can be used only for comparison purposes.
12. Publications including demographic information UN Demographic Yearbook UNESCO, OECD, World Bank Publications Specialized Publications: Population Studies (SUA), Population (France). • The yearbook of demographic periodicals 13. Romanian Periodicals Publications of NHI The Statistical Yearbooks of Romania The demographic yearbooks Results of censuses Newsletters Publications of PHM Yearbooks of sanitary statistics The analyses of infantile deaths, abortions, maternal mortality Results of some demographic surveys Surveys concerning the reproductive health of the population Results of demographic surveys Survey upon the reproductive health of the population 14. Informative documents Medical Civil-state documents Statistical demographic official reports The medical certificate ascertaining theThe birth certificate S.R of births – born alive birth of an alive child The medical certificate ascertaining theThe death certificate S.R of births – born dead birth of a dead child The medical certificate of the person The marriage certificate S.R of deaths having ascertained the death The divorce certificate S.R regarding marriages S.R concerning divorces S.R for changing the address 15. Reference points of the population statics The statics of the population studies the number and the structure of the population Population types The local population – the population that has the legal address (registered in the ID card) in a specific place. The stable population – the legal population and the population living for a period of some months in a certain place, pupils and students studying in a certain place. The open population – the population affected by the external migration. Te closed population – the population unaffected by the external migration. The stationary population is the stable population that presents a o growth rate and a constant age-structure. 16. I. The number of the population Registered no.
3 • Census – the transversal global registration of the population at a certain moment in time. • 2002: 21.680.974 ; 48,8 %M; 51,2 %F Calculated / estimated number Sources: Civil state offices. The population evidence bureau (Police) . Demographic surveys – study thoroughly elements referring to the structure and the dynamics of the population. 17. The evolution of the population in Romania 18. The number of the population 19. The number of the population 20. The evolution of the population number in Bihor county 1930-2002 21. II. The territorial distribution of the population • The percentage of the population with a stable place of residence in U/R %U=Pu/P x 100 The urban population -52,7 % The rural population - 47,3 % • The distribution of the population in relation to the type and the dimensions of the locality 2001: 265 municipalities and cities: c.m.m. 10000-20000 inhabitants 2686 communes: c.m.m. 1000-3000 inhabitants Density indices 22. The dynamics of the population distribution in relation to residential environments between 1930-2004, Romania 23. Density /Dispersion The density of the population represents the ratio between the number of inhabitants and the surface of the place on which they live. Dispersion represents the degree of the population’s diffusion within constituted collectivities. 24. The densitaty of the population Measures the degree of the population’s dissipation within constituted collectivities (cities, villages) D=P/S ROM: 96,0 /Km2; 189,6/Km2 IIf0v; 175,8/Km2 PH; 30,4/Km2 TL A/reality index=S/P Physiological density index= P/cultivable surface Agricultural density index = P in agriculture / cultivable surface 25. II. The structure of the population Sex Age groups Civil state Participation to the economic life Depends upon: Economic development policies Life environments Influences: the morbidity model
4 mortality the structure of health services 26. The structure of the population (Sex) At birth, the percentage is higher for the male sex the proportion changes in favor of the female sex around the age of 35, given the masculine over-mortality The existence of a feminine over-morbidity and of the masculine over-mortality is characteristic for the sex specificity 27. The structure of the population (Sex) The percentage of the feminine/masculine population: PF(M)/P x 100 - The masculinity / feminity index: PM/PF x 100 At birth = 105-1 06 males at 100 females (in most countries) The women over-plus: PF-PM/P x 100 28. The structure of the population (Sex) Number of men 61574398 X K = X 100 = 96,2 Number of women 63995848 In 1995, in Japan, there were 96 de men at 100 women In Chile, in 1995, for the age-group 60-64, there were 85 men at 100 women, and 54 for the age group of 80 and more In 2006, in România, the masculinity ratio was of 95 men at 100 women. For the population segment of 85 and more, the masculinity ratio was of 49 men at 100 women. 29. The structure of the population (age groups) • The characteristic graphic representation of the population structure in relation to age- groups and sex = the age pyramid Age groups: yearly, for five years, for ten years, large groups 30. The structure of the population in terms of age groups 32. Population in relation to age and sexes on 1st of July, 2005 in Romania 33. Models of age-pyramids The triangle pyramid, -“young populations". High birth-rate alongside high death-rate, the index of net reproduction being over-unitary (developing countries). “Bell” pyramid – increases the living standard and the average life-span, = average ageing (rapidly industrialized countries) “Urn” pyramid: accentuated ageing process – low birth-rate and high longevity, % high number of elderly people ( developed countries) The “clubs” pyramid – Aged population, with a strong rejuvenation in the last period, countries developed with intense pro-birth policies and high indicators of birth rate. 36. THE DEMOGRAPHIC AGEING OF THE POPULATION A great triumph of humanity, after the age of 15 A great provocation
5 Hope of life at birth (the average lifespan) - represents a synthetic indicator of mortality and at the same time of the health state. Is the average number of years that a person hopes to live in the conditions of the characteristics of the mortality model on age-groups of the population to which the person belongs, for a certain year. 37. The structure of the population (The civil state) After the age of 15 Unmarried Married Widow/Widower Divorced Consensual union Indices % married persons % unmarried persons % divorced persons % widow/widower pers. 38. Nuptiality / Divorciality 39. The structure of the population (Participation to economic life) Active population = pers. cu 0 profession + unemployed NO: pupils, housewives, students Occupied population = pers. with 0 occupation PO = PA - unemployed Inactive population = pers. without activity: children, elderly persons 40. Indicators Indices Formula Activity indices Pactiva/P x 100 Indices of sex-specific activity PMA/PM x 100 Indices of activity specific in terms of age- P Agr. Age/ P respective age x 100 groups The economic-dependence ratio Pop. 0-14 years+60 years and over/pop.15-59 years x 1000 The dependence ratio of elderly people Pop 60 years and over/ pop 15-59 years x1000 41. The dependence ratio Population of 0-14 years+ Populațion of 65 and over 11245500+9015000 xK x 100 = 53,0 Population 15-64 years 38232800 - in 1996, in France, the demographic dependence ratio has been of 53. In other words there were 53 persoans at the age of dependence (0·14years and 65 years and over 65 ) at every 100 persons with an appropriate age for work (15-64 ani). - in 1997, in Japan, the demographic dependence report has been of 45, with a proportion of 15%~ from the total of the population of children under 15 and a proportion of 16% of elderly persons (65 years and over). - in 2006. in Romania, the dependence ratio has been of 44 young persons (0-14 years) and elderly persons (65 years and over 65) to 100 persons with an appropriate age for work (15-64 ani). 42. The dependence report 43. The implications of the population statics
6 Demography M, N, F, divorce-rate, marriage-rate – infl. of str.on age-groups and sexes The percentage of elderly people increases – the ageing of the population Over health services No. pop. – correlated with the no. of doctors, no. of beds Density of the pop.- sanogenetic/pathogenetic effect The structure of the population Economic Density of the population in relation to resources The dependence index The percentage of the active population 44. THE DYNAMICS OF THE POPULATION Synonyms: The reproduction of the population The natural movement of the population 45. The reproduction of the population (natural movement) The phenomenon of permanent renewal, through the birth of a new generation every year, alongside the leaving of a generation, through death In a limited sense: natality + fertility In a broad sense: natality + mortality 46. Concepts Born alive – is the product of conception, completely ejected or extracted from the mother’s body, irrespective of the duration of pregnancy of which it is a result and which presents a sign of life: respiration, cardiac activity, pulsations of the umbilical chord or the contraction of a voluntary muscle, whether the placenta has been eliminated or not, or whether the umbilical chord has been sectioned or not Born dead – is the product of conception which results from a pregnancy of over 28 weeks that, after the complete separation from the mother’s body, presents no sign of life. Determining the duration of the pregnancy is difficult. Usually a direct information is preferred as criterion, such as a weigh of the fetus of over 1000 grams and a height of over 35 cm. Abortion – is the product of conception which is the result of a pregnancy of less than 28 weeks that, after the complete extraction from the mother’s body, does not present any sign of life. For the same reason mentioned above, as a criterion, one can refer to a weigh of the fetus of over 1000 grams and a height of over 35 cm. 47. Concepts The conception product is the result of the fecundation of one ovule by a spermatozoon, which has gone through the period of gestation and results in either a birth or an abortion The birth is the event marking the expulsion of a conception product after a period of pregnancy of over 28 weeks. The birth rank indicates the specific birth, out of the number of births (with a child born alive or dead ) of a specific mother. The newborn rank – indicates the number of the newborn (either alive or dead) in the suite of children born out of a certain mother. The preotogenesis interval – represents the average duration between the time of marriage and the birth of the first child. The intergenesis intervals – represent the average time-spans that separate, in a certain population, the births of successive ranks (the average duration between the first and the second, the second and the third pregnancy, etc.).
7 48. Concepts Demographic behavior – the attitude of a couple as regards the number of children in a family, the dimension of their own family and the interval between births. The fertile age of a woman – the ages between which the woman can give birth (from a demographic point of view = 15-49 years), • Family planning – the conscious decision of a couple with regards to the number of wanted children and the intervals between births. 49. Natality - Fertility 50.Measuring natality and fertility During a year’s time (transversal approach) On a 0 generation (longitudinal approach) 51. Natality Definition – the demographic phenomenon marking the appearance of children born alive in a certain population and during a specific period of time. The observation statistical unit: the child born alive Measuring: the rough natality rate N n = x 1000 P 52. Informative documents The medical certificate acknowledging the birth The birth certificate The statistical birth report 53. The Evolution of Natality in Romania 1930·1935 ·30 live births at 1000 citizens The Second World War - Natality decreases due to the disorganization of families; the birth rate increases after the end of the war (1949 - 27,6 %o) After 1957· the liberal practice of interrupting pregnancies results in a rapid decrease of natality (1966 -14,3 %o). 1966 – The decree interdicting the surgical abortion - 1967 - 27,4%o, then it starts to decrease, in 1983 N is similar to that of 1966 ( 14,3 %o). After 1990 – the liberalization of the abortion as a result of family planning programs (1990 -13,6%0 ;2008 -10,2 %0) 54. Romania’s natality within the European context, 2005 55. The Evolution of Natality in Romania 56. Fertility • Definition – the demographic phenomenon of the live births’ frequency at the female population at the fertile age (15-49 years). • The statistical observation unit: the live birth • Measure: the general fertility rate 59. The general fertility rate (GFR) Expresses the frequency of live births at 1000 women at the fertile age (15-49 years) The number of live births x 1.000 gf = The number of women of 15-49 years Influenced by: Specific age-group fertility The structure in terms of age-groups of the female population
8 Rom: 2000 - 44%0 60. Fertility 61.Fertility in Romania related to the global context 62. The total fertility rate in the European context 63.Fertility 64.Fertility 66. Other indicators - fertility The specific fertility rate in terms of age-groups The number of children born of women of the X age fx= x 1000 The number of women of the X age The legitimate fertility rate The fecundity rate The mortality rate 67. Synthetic indicators - fertility The total fertility rate – the average number of children that would be born of a woman who, in the absence of M, lives through the age-interval 15-49, being affected, at each age, by the same intensity of f. that can be appreciated at the studied moment of a certain age. Value: 1,3 children / woman The gross reproduction rate (GRR) GRR=TFR x 0,5 (= 0,65) TFR – total fertility rate; 0,5 – the percentage of female babies at birth Value: 1,15-1,2 girls / woman The net reproduction rate 68.Fertility 70. The reproductive behavior Synthesized in the average number of female sex descendants that a 0 woman gives birth to during the period of her fertility. Enlarged reproduction: the average number of girls > 1 – the generation replaced by the 0 generation, with a effective Narrowed reproduction: the average no. of girls < 1 – the fertile generation is replaced by a 0 generation, which is more numerically reduced. Stationary reproduction: Average no. of girls = 1 71. Indirect indicators of the reproduction of the population The average age at the first marriage = 24,2 for women / 27,1 for men The proteogenezic interval = 22 - 23 months, but it presents variations in relation to environments, occupations and the educational level Intergenezic intervals = between the first and the second child = 3 -3,5 years 72. Factors influencing natality and fertility (I) Demographic factors: % female pop. at the fertile age The age at the time of the marriage Nuptiality and divorciality Infantile and juvenile mortality The structure of the family Physiological factors Feminine/masculine sterility The duration of the procreation period 9 The frequency of fetal mortality Socio-economic factors: Macroeconomically PIS/loc The urbanization level The industrialization level Microeconomically The educational level of women The employment of women in the economic activities Average revenue / family member
73. Factors influencing natality and fertility (II) The migration of the population Legislative factors The provisions of the Labor Code and the Family Code The system of grants-in-aid for children Programs for the maternal-infantile protection The family planning policy Subjective factors: associated with the notion of family planning No. of wanted and born children Contraceptive methods and means Cultural factors: local habits, religion 74. Main factors influencing the decrease in fertility Women emancipation Increased duration and level of education Weakening of cultural norms influence Costs for children Reducing the economic function of children The introduction of modern contraceptive methods Economic factors: deterioration of the living standard, unemployment, stress. 75. Favourable factors to fertility Marriage-age is not advanced High nuptiality Low divorciality 76. MORTALITATY Mortalitaty represents the negative component of the natural evolution/movement, being the demographic phenomenon of death in a specific population and during a given period of time (usually one year). The demographic event of this phenomenon is the death. Death represents the event marked by the definitive disappearance of any sign of life, at any time after the registration of the live birth. 77. The importance of studying mortality Mortalitaty is a demographic phenomenon with implications upon the numerical growth of the population and in the age-structure of the population, which contributes to the achievement of a balance in the structure of the population on age-groups; Mortality represents one of the demographic indicators used in measuring the health-state of the population;
10 Allows the identification of health-related problems and the setting of priorities in health- related actions; Allows the setting of objectives within health-related programs; Can be used in the process of sanitary planning of resources; Allows the evaluation of efficiency of the activities related to the sanitary-services system. 78. Mortality / economic-social development The economic-social development determined the decrease of mortality and the growth of longevity and of the life-quality. A decline in mortality has been registered in the world as a result of complex actions aimed at health and economic development. Initially the decline was visible in developing countries; In developed countries, a deterioration of the increase in potential years of life can be observed, phenomenon associated with the ageing of the population. The relation between the economic-social development and the health-state of the population can be briefly represented through the correlation existing between the gross national revenue per capita and the average duration of life, as synthetic indicator of mortality and of the health-state. 79. The health-state/ socio-economic development The increase of the gross national revenue per capita is accompanied by an increase in the average duration of life. If the gross national revenue increases, and the percentage allocated to health remains constant, the fund for health will increase in its absolute value 80. Factors influencing mortality, expressed by the life-expectancy at birth Economic factors; The distribution of the national revenue; Other factors; The structure of the population in terms of age-groups; Factors related to the quality of the environment; The availability of knowledge and technologies. 81. Global factors having limited the decrease in mortality Development strategies having ignored health. The reduced percentage from the structure of the budget for the protection of health, through the absence of the budget’s correlation with health-related interests, the needs related to health or the improvement in the quality of medical-assistance. Inadequate structures of the health system, demonstrated by the unbalanced development of specialized and hospital care in relation to the primary and extra-hospital assistance, which have not been adapted to national needs and other particular aspects, alongside an irrational use of resources. Models taken from developed countries have been transposed to developing countries Health-related technologies, which are not correlated to specific problems. 82. Trends A decrease in mortality associated with cardiovascular diseases, a decrease that has not been anticipated; A decrease in infantile mortality that is below the expected level in developed countries (under 8o/oo); Higher death-risk in the case of men, caused by a specific way of life;
11 Inequities in the distribution of mortality in terms of geographical areas or socio- professional categories. 83. Sources of information Total and continuous registration of deaths at the civil-state services alongside town-halls, on the basis of the medical certificate ascertaining the death, signed by the doctor who has recorded the death; Information concerning the number and the structure of the population in relation to a series of variables (sex, age, residence environment, etc.). 84. Analysis methods transversal: the analysis of mortality during one year or during a certain period of time; longitudinal: prospective or retrospective, where the mortality analysis focuses on a cohort or a generation 85. Indicators used in measuring mortality The general mortality rate (gross mortality index), which estimates the frequency of deaths at 1000 people. The specific mortality rates (in terms of sex, age-groups, medical causes of the death), which estimate the frequency of deaths in the case of sub-populations. Proportional mortality (lethality), which represents the percentage of deaths characteristic of a certain category of people, related to the total number of deaths. Standardized mortality ratio (SMR). The biometric functions from the mortality charts. 86. The general mortality rate - Measures the frequency of deaths at 1000 inhabitants. - M= no. of deaths / average no. of inhabitants x 1000 87. Specific mortality rates measure the frequency of deaths in the case of sub-populations - in terms of sexes: Mm,f= no. of deaths in the case of M or F / average no. of M or F population x 1000 - in terms of age-groups: M (specific to a certain age)= deaths at the respective age/the population of a similar age x 1000 - in terms of death causes: M cause = no. of deaths associated with a certain cause/the total no. of inhabitants x 100000 - in terms of environments: MU/R = no. of deaths in the U or the R environment/ no. of inhabitants in the U or the R environment x 1000 88. Proportional mortality (lethality) Represents the percentage of deaths of a certain category from the total number of deaths. Mprop = no. of deaths due to a certain cause / total no. of the deceased person x 100 the main decease causes : Cardiovascular diseases - 61,7%; Malignant tumors - 14,6%; accidents, traumas , poisoning - 6,03%; Respiratory diseases - 5,9%; Digestive diseases - 5.9%. 89. The standardized mortality rate.
12 The standardization of mortality = a way of eliminating the influence of different age- structures of the population upon mortality. Allows the correct comparison of registered mortality levels in two or more populations, which are structurally different. There are two classic procedures: The direct method (the method of the standard population). A reference population is chosen, namely the standard population, with a specific structure in terms of age-groups. To this population the real, age-group specific mortalities, from each of the areas compared, are applied and thus the standardized rates of mortality, for the respective areas, are obtained, The rates express the expected frequency of deceases, under the hypothesis that each area would have a similar structure in terms of age-groups, respectively the structure of the reference population. The indirect method (the method of standard mortality). A model of specific mortality, related to age, is chosen as a reference, standard model. This model is applied to the real structure, related to age-groups, of each of the areas compared. We obtain the expected frequency of deceases under the hypothesis of a standard model of specific mortality. 90. The standardized ratio of mortality Represents the ratio between the number of deceases observed and the number of expected deceases. Measures the excess of mortality registered in a population in relation to a standard model of specific mortality. 91. The mortality table Represents a method of measuring, analyzing and comparing mortality. It allows the calculation of some indicators called biometric functions, which are as follows: the number of survivors - lx or Sx the number of deaths - dx – represents the number of deceases registered in a fictive generation of 100.000, if this generation confronted the decease risks from the mortality model registered in the year taken into consideration; decease probability - qx survival probability - px life-expectancy at different ages - ex 93. INFANTILE MORTALITY The demographic phenomenon of deceases at the age of 0-1, registered among the population of children born alive, during a certain period of time and a certain territory.
Represents a specific indicator of measurement and description of children’s health-state, being considered at the same time a synthetic indicator of a population’s health-state Represents an indicator for the quality of life and an expression of the efficacy of the health-service system. Economic-social and environmental factors, as well as elements related to the health-care system, influence the health of children aged 0-1. 94. Indicators The infantile mortality rate = no. of deceased children aged under 1 year/no of live births x 1000
13 95. Indicators The infantile mortality in terms of age-groups: - neonatal mortality = no. of children deceased during their first month of life (0-27 days)/no. of live births x 1000 - precocious neonatal mortality = no. of children deceased during their first week of life (0-6 days)/ no. of live births x 1000 - tardive neonatal mortality = no of deceased children in a period of 7-27 days/ no. of live births x 1000 -post-neonatal mortality = no. of deceased in the first year of life – 11months/ no. of live births x 1000 - Perinatal mortality = (no. of children born dead + no. of deceases 0-6 days) / no. of live births x 1000 96. Indicators Infantile mortality in terms of sexes M M/F = no. of deceses 0-1 year M, F x 1000 / no. of live births M, F Infantile mortality in terms of environments M U/R = no. of deceases 0-1 year U, R x 1000 / no. of live births U,R Infantile mortality in terms of decease causes = no of deceases 0-1 year, due to a certain cause, during a certain time-period x 1000 / no. of live births during that particular period Mortinatality (tardive fetal mortality) = no. of children born dead during the period under analysis x 1000 / (no. of live births during the same period + no. of children born dead during that respective period) 97. Risk-factors for infantile mortality Mother-child biosystem: Endogenous factors: - associated with the mother: - age (under 19, over 35 ani); - parity; - abortions in antecedents; - general and obstetrical pathology; - accidents during birth; - obstetric interventions. - associated with the child: - low weight at birth; - the male sex; - the newborn’s rank; - age (first semester); - biologic handicaps (malnutrition, rickets, anemia, malformations, infections due to the interference with the exogenous factorsi). Exogenous factors: - intoxications; - accidents; - environmental factors (the medical assistance being included here). Factors related to the family: - the civil state of the mother (unmarried mother); - disorganized family; 14 - low instruction level; - the family revenue; - unsatisfactory living conditions; - families with an unstable residence; - alcoholism; - vagrancy; - young families, in their first year of marriage. Demographic factors: - variations in the evolution of natality and the fecundity; - family planning. In the case of Romania, for a period of 55 years, the correlation coefficient of ranks between the infantile mortality and the gross natality rate indicated a rather weak correlation (r=0.54). Economic and environmental factors. 98.Demography 99. Demography 100. Demography 101. Demography 102. Demography in Romania and its neighboring countries in 2005 103. Romania’s Demography within the European context
1. Lecture 3. MORBIDITY Ass. Prof. Ph.D. Daina Lucia
2. DEFINITION Definition: the total number of known registered illnesses: At a certain moment, Or during a certain period of time, In relation to a population living within a well-defined territory, Whether the morbidity cases: Have been identified during the determined period, either at the moment of falling ill or afterwards (even at death time), The identification was done at a previous moment but the disease continues to the present moment Whether the state of disease ceased (cure, death) or not during the period taken into consideration. 3. Through international consensus, within the category of morbidity the following are also included: traumas accidental or voluntary poisoning (homicide, suicide), wounds, traumatic accidents burnings caused by wars. 4. Forms associated with the study of morbidity: General morbidity Incidence 15 Prevalence – momentary periodical Contingent morbidity Successive morbidity Morbidity associated with temporary incapacity to work Morbidity associated with permanent incapacity Hospitalized morbidity 5. Concepts employed in the study of morbidity: Disease or falling ill: nozologic entity characterized by the alteration of a person’s health Disease or ill person: the notion of disease is not similar to that of diseased/ill person, since the diseased person can suffer from more than one illness simultaneously. 6. Concepts employed in the study of morbidity Clinical case = ill person in morbidity = “new case”/”old case” New case identified = diagnosis at the first medical consultation, when the case is also registered. The new case identified may be: clinically new case Statistically new case (although the moment of being taken ill could have been identified years ago, as it is the case with chronic diseases) Old case = already diagnosed and registered case, which subsequently requires consultation for treatment, dispensation, etc.
7. Concepts employed in the study of morbidity Codification = means of replacing the text with conditional signs or figures. In order to establish an internationally common language, the WHO made an international list of causes of illness and death (International classification). It uses scientific criteria accepted worldwide: etiology, clinical manifestation, anatomic location, or mixed criteria. This classification is periodically revised, as a result of expert committees meetings. th Currently, the 10 revision, by WHO, of international classifications on 1000 causes of disease and death, from 0 to 999, is being used. 8. Concepts employed in the study of morbidity The codification – new case relationship The new case is codified at the moment of diagnosis (in the informational system created by WHO) and is included in the calculation of incidence. After curing, in case of recurrence, it will be codified again as a new case (i.e. acute diseases). The old case is codified just once, at the first diagnosis, and is included in the calculation of prevalence (i.e. chronic diseases). 9. In the study of morbidity, the desideratum of WHO is to include the entire population in the study and the organization of a pertinent informational system. The aims of WHO operational system describing the actual health-state of the population, by means of a passive informational system; the early beginning of monitoring the health-state,by means of an active informational system;
16 Forecasting tendencies, in order to achieve an optimal and efficient prevention, as well as plan resources, elaborate strategies, evaluate the efficiency of medical-care services, or of the medical act quality. 10. The importance of the informational system: WHO believes that the informational system should rely on gathering data with the help of habitual administrative procedures, placing emphasis upon the consultation of patients who are not institutionalized (in the GP’s consulting room, of the specialist doctor in policlinics). When medical care is given in public health centers (general or specialized medicine), the statistics created by these institutions reflect quite faithfully the general morbidity of the population. Data are combined and compared with the ones obtained from hospitals, the statistics of Medical Insurance Centers, and the results of well-organized medical surveys. 11. General morbidity Includes several types of indicators, depending on the moment at which the disease occurs, or the severity of cases. 12. INCIDENCE Definition: the frequency of new cases registered within the limits of a certain territory and during a specific period of tie (month, semester, year) at health centers (factory or territorial). Since 1987, hospitals and policlinics must report new cases of morbidity, registered in the record/evidence cards of chronic diseases. When calculating incidence, chronic diseases are registered just once, as “new cases”, at the diagnosis time. Acute illnesses that are cured but appear lately as new disease cases, rather than as a recurrence, are considered again new cases (i.e. new cases of flu, after two months from the curing of a previous flu episode). When several diseases are diagnosed at the same person, each one of them is codified.
13. INCIDENCE Represents the frequency of new cases registered at a given population during a given period of time It appears that the time dimension is taken into consideration The daily, weekly, or monthly incidence can be calculated The yearly incidence is more frequently used, as it reflects the duration of the disease and the extent of the epidemiologic process 14. INCIDENCE The incidence rate represents the number of new cases recorded during a specified time-period, relative to the population at the middle of this period 15. Calculating formulas Total incidence indices: new identified cases (nc) It= x 1000 average number of inhabitants (I) 16. Calculating formulas Specific incidence indices (in terms of sex, age-groups, etc.): nc (c,x) Is = x 100000 Ix Is = specific incidence index nc = new recorded cases of disease (new case) c,x = new recorded cases of certain diseases, at certain ages 17 Ix = average number of inhabitants of a certain age 17. Calculating formulas Maximum value: over 10000/00 because a person can suffer from several diseases Minimum value: It can’t be 0 because any disorder is usually registered Average values: 400 – 5000/00 inhabitants 18. Calculating formulas Number of new cases of the “X” disease Cause-related specific morbidity = x100000 Number of inhabitants Indicates the frequency of new cases of a certain disease within a certain territory and a specific period of time 19. Calculating formulas Specific morbidity in terms of causes and age-groups Number of new cases of the “X” disease at the “Y” age = x 100000 Number of inhabitants of the ”Y” age 20. Calculating formulas The structure of morbidity incidence No. of new cases of the”X” disease = x100 Total no. of diseases Indicates the frequency of a certain disease in relation to the total number of diseases The ranks of morbidity structures are obtained (as in the case of mortality) rank I: diseases of the respiratory system rank II: diseases of the digestive system rank III: diseases of the nervous system and of the sense organs 21. The incidence speed Refers to the changing of incidence in the time-unit Speed reflects the changing of a variable on the changing unit of another variable, which depends on the first one The incidence speed should take into account not only the real time for the observation of subjects, but also the variable moment when the observation of subjects begins 22. The incidence desnity Incidence data should be reported, when possible, at the denominator represented by persons – observation (exposure) time A person exposed to a studied factor for 3 years represents 3 persons – years of exposure, the equivalent of 3 persons exposed for only 1 year Incidence allows us to estimate the speed for the propagation of the disease within a certain population The numerator is the number of persons – periods of risk (days, months, years, the duration of the particular observation). When this situation is not possible, the numerator will be represented by the number of persons studied at the middle of the study – the middle of the year when the annual incidence is measured 23. The incidence density Many diseases do not have a continuous development and appear in the form of initial episodes (outbreaks), with the help of whom the disease is identified – these are followed by remissions and clinically silent periods
18 Epidemiological observations should indicate if the incidence of diseased persons is measured, or if the study focuses on the incidence of episodes or the manifestations of the disease 24. The cumulative incidence rate Represents all new disease cases having occurred during a certain period of time; these are related to the initial effective of the group Represents a measurement of risks 25. The attack rate Is a special manifestation of incidence, being associated with cases when the population is exposed only for a limited period of time 26. The attack rate Examples: Food poisoning from the same source, the explosion of a nuclear charge/warhead, the age group to which the disease exclusively occurs The attack rate indicates the proportion of subjects affected during a definite and completed period of time – for example, the global incidence of an occupational disease for subjects between 20-65 years old takes into account their maximum period of exposure to etiologic factors at their workplace In case of unknown etiologies, the attack rate represents the proportion of subjects affected during their entire lifespan 27. INCIDENCE Incidence represents an important indicator of preventive health-related needs, in the case of both acute and chronic diseases; in case of a widely spread disease, it is also an indicator in the evaluation of control measures efficiency When individual and collective measures are efficient, the incidence of the disease diminishes 28. INCIDENCE The situation, at a certain moment in time, of the occurrence or the development of a disease within a large part of the population, is influenced by the incidence and the duration of the disease For example, if the duration of the disease is significant, the zero incidence and the high prevalence shows that the process of mass-propagation approaches its end 29. INCIDENCE In order to interpret a mass phenomenon, it is possible to associate the culminant point of incidence with the culminant point of the causal factor (which is usually an element of the past), so as to identify the incubation period, the exposure duration and the duration of the disease stages These elements allow the logical interpretation of the mass process that is being studied, with the aim of adopting logical and efficient control methods 30. INCIDENCE For diseases with a relatively stable propagation (i.e. the evolution of cancer in time), the following formula can be applied
Prevalence = Incidence x The average duration of the disease The average duration of the disease = Prevalence / Incidence 31. INCIDENCE Technical aspect: When the duration of the disease is evaluated in relation to the number of days spent in hospital, the day of entrance and the day of leaving the hospital are not taken into consideration. In Canada, the day of leaving the hospital is not taken into consideration. In acting against the propagation of a disease, the decrease in its prevalence can be achieved by: 19 Decreasing incidence – anti-epidemic measures, which keep under control the propagation and the occurrence of new cases Decreasing the duration of the disease, through treatment and other clinical measures Decreasing incidence and the duration of the disease 32. The classification of the mass phenomenon The concentration of the disease cases in time or space presents 3 aspects Epidemiology Endemia Pandemia 33. Epidemy The occurrence of a series of cases, comparable in terms of character, causes (origin), and a net number, which is beyons common expectations Rationing or statistical analysis are employed in order to draw conclusions related to unusual aspects 34. Endemic Mass phenomenon which is not limited in time but is limited in space The absence of limit in time implies the presence of many causes of disease during several decades or even centuries, and the influence of these causes upon several successive generations Exemple: malnutrition is endemic in underdeveloped regions 35. Pandemic Represents a mass phenomenon, involving the concentration of ill subjects within a certain period of time but not within the limits of a certain territory The unlimited space suggests that the disease propagates to the entire population or across several continents, the populations being affected by the studied phenomenon 36. Pandemic Example: the sudden and recent occurrence of flu on several continents and its disappearance, a few months later When animals are also influenced, one can speak of a panzootic The pandemic by respiratory diseases is explosive and relatively limited in time due, on the one hand, to the properties of the etiologic agent, and to the current means of control on the other hand Pandemics caused by digestive diseases generally present a longer duration 37. The classification of the mass phenomenon Name Time Space Epidemics Limited Limited At animals Epizootic Pandemic Limited Unlimited Panzootic Endemic Unlimited Limited Enzootic 38. Logical analysis of rates - according to Sartwell - The logical analysis of rates has been achieved for mortality, but the reasoning/argumentation can be done in analogy with other phenomena Numerator = number of deceases or decease cases 39. Logical analysis of rates - according to Sartwell - 1. What is the degree of exactness of declarations concerning the cause?
20 What is the proportion of deaths reported by the doctor? What is the formation of doctors? To what extent are doctors motivated to make accurate declarations? Has the nomenclature and classification of diseases (especially for a certain group of diseases) changed as a result of extending knowledge in the field? Has the clinical identification of the disease improved as a result of discovering new and more accurate diagnosis or laboratory methods, whose application has become widespread? Are there diseases that can easily be confused with the studied malady, and whose modality has radically changed recently ? 40. Logical analysis of rates - according to Sartwell - 2. Has the statistical treatment been changed ? (changing of classification and of priorities allocation) 41. Logical analysis of rates - according to Sartwell - In the case of denominator (population) 1. Is the measuring of the population, during an entire period of studying particular tendencies, accurate? 2. Has the composition of the population changed in time? A. due to administrative “cutting-ups” (census areas) B. due to changes in the distribution of the population in terms of age, race, or other individual characteristics C. have the adjustments in the presentation of data been adequate (standardization or adequacy of data in terms of age or other criteria, which are likely to vary) 42. Defining the status of patient presents several subjective elements: Identifying the beginning and the evolution of the disease. The patient is unable to objectively identify and describe either the outbreak or the evolution of the disease; the first anomalies are asymptomatic. The occurrence of the first signs, that determine the patient to go and see a doctor The presence of the first signs that can be detected by the patient’s entourage
43. Factros influencing the understanding of morbidity: accessibility approachability the quality of medical acts WHO considers that, when the accessibility, the approachability and the quality of the medical act are optimal, the percentage that remains unknown after the study of incidence is of 25% or even 10%. It is important that all data should be registered in the unique medical sheet, in order to know and understand the real health-state of the population and the improvement in the quality of medical acts. 44. PREVALENCE Definition: the total number of diseases present at the “critical moment 1” (the last day of the trimester, semester, year), or during a certain period 2 (trimester, semester, year). 1zmomentary prevalence 2zperiod prevalence Prevalence is calculated differently, in relation to diseases: in chronic diseases = the totality of new and old cases of disease.
21 45. Calculating formulas: bn + bv Pr. = x 100 L
bn (x) + bv (x) Pr (x)= x 100 or 100000 L (x)
Pr şi Pr (x) = total and age-related prevalence index bn, bv = newly-identified disease cases, previously known (old) disease cases bn (x), bv (x) = newly-identified disease cases, previously known disease cases (at certain ages) L, Lx = average number of inhabitants, the average number of inhabitants of a certain age 46. PREVALENCE Prevalence is being studied because incidence can present significant variations at different moments in time and in relation to different causes: “false alarm” “false respite” Therefore, the calculation of tendencies, which eliminate such variations, is important. Different sources (medical consultations, complex medical surveys, declaration sheets, etc.) are combined in order to understand and determine prevalence. 47. Prevalence studies Prevalence studies use sample groups. Prevalence can be studied in relation to either a single group, or to the entire number of groups. Attention!!! Multiplication is done by 100, not by 1000. It is related to the number of examined persons and not to the number of inhabitants The study of prevalence: momentary – instantaneous periodical – all new and old cases identified during a certain period 48. Calculating the periodic prevalence Daily examination, for a 365-days period The prevalence of the initial moment The entire year’s prevalence Prevalence + new cases Prevalence surveys are done at large time-intervals, when the medical programming or planning is needed 49. National sample-groups have been chosen in: 1949-1951 1964-1965 – unique methodology – on a million inhabitants of 5%; all diseases have been included; very good surface, rather than depth representativeness 1983 – sample group of about 50000 people; width and depth representativeness 1989, 1997 – surveys with a similar methodology and comparable data Specifically stratified sample group (three stages):
The first stage was that of dividing the country in 6 areas, plus Bucharest municipality
The second stage marked the separation of each area in urban and rural zones
The third stage was that of selecting 166 urban and rural locations, the same for all the surveys A representative sample group of 11600 persons has been chosen: these persons were evaluated during the investigation
22 50. Successive morbidity Can be appreciated when evaluating (surveying) the health state of the population. The longitudinal, successive study allows the establishment of causality connections for the occurrence of diseases, aggravation of complications, the association and simultaneous occurrence of certain diseases, as well as the identification of those categories of persons that remain healthy throughout the years (potential protection factors can be studied). Allows the evaluation of medical activity aimed at the prevention of morbidity, including the non-observance of preventive programs. Allows the carrying of scientific studies, with data established by the doctor rather than the patient, which might eliminate errors in the appreciation of anamnestic data. 51. Successive morbidity Year after year, the number of diseases at the same group of persons can be observed, as well as the more frequent associations of diseases, the implications of some disorders in the occurrence of chronic diseases, etc. The case histories of patients are not evaluated; instead, the historical link between the events that lead to disease are successively taken into consideration. Represents the study of new cases of disease, identified during a year, as well as the study of severity (intensification, relapse) of previously registered chronic diseases. Allows the dynamic evaluation of morbidity in terms of sexes, causes, age-groups, therefore giving the possibility to make pertinent comparisons among regions or areas that are different in terms of age groups, without making standardization necessary. 52. Successive morbidity Allows the longitudinal sectioning of morbidity, in relation to the segmentation of the population in the categories of healthy and, respectively, ill persons. Given the fact that it includes reference to the acutization of chronic diseases – in relation to causes, age-groups, environments, etc. – but also data about persons that presented no aggravation of the disease in that particular year - in relation to causes, age-groups, environments, etc. – it achieves a complete and complex study concerning the morbidity of the population. Allows the identification of the number of cured persons, of persons falling ill (from among the healthy population), of new diseases contacted by patients already suffering from one, two, three other diseases, the number of deaths, etc.
53. Contingent-related morbidity The survey of the health state allows the study of morbidity in terms of numbers of persons, more exactly in terms of the percentage of ill persons belonging to a certain community and the number of diseases an ill person suffers from. Contingent = number of persons selected on the basis of common characteristics (age, sex, occupation, environment, etc.). From the perspective of Public Health and Management, the study of contingents allows the identification of the populations’ health state and the setting of the following sub-categories :
Healthy persons
presenting risk-factors
without risk-factors
patients
presenting risk-factors
suffering from one, two, or more diseases
without risk-factors 54. Contingent-related morbidity
23 Morbidity in terms of contingents is higher in urban, rather than in rural areas, and at the female sex. In terms of age, the 30-34 group presents a contingent-related morbidity index that corresponds to the average national index. The indices obtained generally present a line that is quite similar to that of the morbidity prevalence, though it has a lower level. Differences are not so obvious between 0-24 years, but become more pronounced with the advancement in age. In terms of environments, the distribution of contingent-related morbidity on age-groups describes a curve that is similar to that in the urban environment, though it presents a higher level. For the 0-14 years age-group, the indices form urban areas are lower than those obtained in rural areas. From the age of 15 onwards, all the age-groups in urban areas present higher values than in the rural areas. 55. Contingent-related morbidity Supra-morbidity has been registered in the case of women belonging to all the age-groups, with the exception of groups between 0-9 years and over 80. The minimum indices are registered at the age-group of 15-19 years, these being lower in the case of males. Maximum indices are registered at males over 80 and women belonging to the 74-79 years age-group. The efficiency of preventive or curative measures is evaluated through the longitudinal study of successive morbidity. 56. Morbidity in terms of age-groups The incidence of morbidity differs in terms of age. The awareness of tendencies allows the adaptation of medical services (preventive actions; material, human, time-related or financial resources, etc.). 57. Morbidity causes: Up to 1 year - perinatal actions
- respiratory diseases
- digestive diseases
- infectious or parasite-related diseases
1-14 years - respiratory diseases
- digestive diseases
- accidents
- infectious-contagious diseases
14 years - “the golden age”
15-19 years – minimum indices
20-60 years – acute respiratory and digestive diseases
- chronic diseases
- professional diseases
at 30-40 years, the contingent-related morbidity index corresponds to the average national index;
60 and over 60 - chronic diseases 58. Morbidity in terms of sexes A supra-morbidity can be identified at women belonging to all age-groups, with the exception of the age-groups between 1-9 years or over 80 years (through contingent-related successive morbidity). 24 Possible explanations higher vulnerability of the female sex genital pathology Iuliu Haţieganu described the so-called “dextritis”- affection of the right ovary, the gallbladder, or of the appendix, but in reality it seems that women have a higher level of medical culture, which makes them more aware of health-related risks; given their multiple roles within the family, women present a higher addressability to medical services.
59. Environment-related morbidity Contingent morbidity is higher in urban, as compared to rural areas. In terms of age-groups, a curve similar to that of the set environment can be observed, though it registers a higher level in the urban environment. For the 0-14 years age-group, the indices in the urban environment are lower than in the rural environment. From 15 years on, higher values are registered in urban areas. This increase is apparent because: Addressability and accessibility are higher in the urban environment The quality of medical acts is higher in urban areas The level of culture and education for health is higher in the urban environment The registration and report of cases is better in urban areas 60. The transition of morbidity
Is secondary to demographic transition, being a consequence of the latter but also of the socio-economic development.
The phenomenon is placed between the two types of morbidity and mortality:
primitive
evolved
“Primitive” morbidity
endemic: infectious, parasitary, digestive acute diseases;
Characteristic to underdeveloped countries, where a high-frequency of chronic diseases is also encountered.
Morbidity of the “evolved” type
High prevalence of chronic diseases: hypertension, ischemic heart disease, chronic pulmonary heart, digestive or renal chronic diseases, diabetes, etc.
Characteristic of economically and socially developed countries, associated with the increase in the percentage of elderly people
“Intermediary” morbidity- characteristic of developing countries, which present a decreasing infectious pathology and an increasing chronic pathology. 61. Morbidity with temporary working incapacity ( T.W.I) – Studies aspects of morbidity at the active, employed population. Refers only to diseases that determine the temporary incapacity to work, and not to any kind of disease. Includes both newly identified cases and the aggravation of already registered chronic diseases. Morbidity with T.W.I is studied on the basis of the medical certificate referring to disease and incapacity to work (medical leave certificate). Starting from T.W.I. – related data, the following indicators are calculated:
Frequency index – indicating the number of initial certificates, related to the number of employed persons ;
25 Severity index – relates the number of T.W.I. (initial + subsequent certificates) to the number of employed persons . The correct study of T.W.I. – related morbidity is achieved by calculating the severity index in terms of sexes and age-groups, both in comparing indices in dynamics and the situation among counties. 62. Hospitalized morbidity Is studied starting from WHO’s international list of disease classification; represents the study of frequency of patients who need hospitalization. No. of patients hospitalized at the beginning of the reference period + new hospitalized patients during the respective period Hospitalization frequency = x 100 Average no. of inhabitants Hospitalized morbidity can not characterize the real morbidity of the population because it depends on the degree of accessibility and addressability in hospitals, and on the fact that not all diseases require hospitalization.
1. LECTURE 4. EPIDEMIOLOGICAL METHODS IN PUBLIC HEALTH 2. Epidemiology – • definition = the study of the distribution and of the factors determining the health state and the events taking place in different populations, as well as the application of results to the control of health-related problems • Object = population groups – The target population (for example, that living within a defined territory); – Particular group of patients (clinical epidemiology); 3. The objectives of epidemiology • 1.Describing the distribution of diseases or of risk factors in human populations. – 1.1.Describing the distribution of diseases or of risk factors in relation to the personal characteristics of individuals within the evaluated group – 1.2.Describing the tendencies or the temporal evolution of diseases and risk factors in populations. – 1.3.Describing the geographic (spatial) evolution of diseases or of risk-factors. • 2.Explaining the etiology of diseases or of the way they are transmitted. Proving the existence of some relationships among explanatory factors and the results these factors generate (risk-factor – the disease). • 3.Prediction related to the probable number of diseases in a given population and to the character of disease distribution in that particular population. • 4.Background programs aimed at health prevention and control in a certain population, or at improving health services for individuals. 4. Methods used in epidemiology: • - the current system of sanitary information; • - biostatistics; • - special methods for the definition and determination of the sample groups; • - techniques of risk-measurement; • - techniques of survival measurement; • - standardization, etc. 5. Types of epidemiological investigation • descriptive
26 • analytical • experimental 6. DESCRIPTIVE STUDIES 7. Definition: • Describe the models of disease occurrence or of exposure to risk-factors, in relation with: • Individuals (WHO suffers from the disease) • Place (WHERE do we encounter, to a higher or lesser degree, a certain disease) • Time (WHEN does the disease appear) 8. Information • Determines the sub-groups within a population that are exposed to the highest risk (target groups for interventions) • Supplies information for the generation of hypotheses • Monitors long-term trends of diseases or of exposure to diseases • Compares the features of those with or without exposure or result 9. Types of Descriptive Studies • Co-relational or environmental studies • Case or case-series reports • Cross-sectional surveys 10. Correlation studies • The characteristics of the entire population are described in relation to the disease occurrence • The correlation coefficient, r., is the descriptive measure used • Quantifies the correlation or the linear connection between exposure and result 11. Reports/Case Series • Case report: Describes the experience of a single patient • Case Series: Describe the experience of a group of patients 12. Transversal investigations • The state of exposure and of disease are evaluated at the same time and in a certain population • An image of the population’s health state Descriptive investigations 13. Advantages • They are generally facile and rapid • Relatively cheap • Allow the understanding of the way diseases occur in time • Gather data about risk-factors • A base for the planning, supply and evaluation of health services provided to a given population 14. Descriptive investigations - Disadvantages - No official comparison group - The temporal connection cannot be identified easily - It is possible to provide no data at the individual level - It cannot evaluate causality
27 - It cannot test the etiological hypothesis 15. ANALYTICAL EPIDEMIOLOGICAL INVESTIGATIONS • Cohort investigation • Control case investigation 16. COHORT INVESTIGATIONS • The analytical investigations, epidemiological investigations of the observational type, study the relationships between two categories of different events (the risk factor and the disease) and allow causal-type inferences • Factors relevant to any analytical investigation – The object of investigation – The evaluated population – The evaluated variables. 17. Exposure to risk-factors • The variables investigated during an epidemiologic investigation are: – exposure – effects. • Exposure refers to any factor believed to be causal or responsible for a certain result. Exposure may be: – active – attributed by the investigator or – passive – such as age, sex. • Exposure may be natural, intrinsic to the human body, behavioral, treatment-related, etc. 18. The purpose of cohort investigations • Prove the existence or the inexistence of an epidemiologic association • Check if the epidemiologic hypothesis is true or false • Produce epidemiologic inferences of the causal type 19. Types of cohort analysis • Actual prospective surveys, when the disease/death are seen as results of the exposure preceding them • Investigations of the retrospective type, where data about the risk factor and the disease are gathered in the past • Investigations of the historic-prospective type (doublespective) where exposure and the result of exposure to risk occurred in the past • The evaluated cohorts may be fixed or dynamic. 20. Methods used in the cohort investigation • The investigation model differs in relation to the way of choosing the sample group. • This may be representative – for the entire population – For two cohorts (the one that is exposed to risk and the one that is not exposed to risk) 21. Type 1 model • A sample group for the target population is chosen and subsequently self-divided in two groups: one that is exposed to risk, and the other one, that is not exposed to risk • Then the investigators supervise the persons exposed and not exposed to risk, waiting for the occurrence of the disease or of death. 22. Type 1 model 28 23. Type 2 model • Two sample groups are chosen, one including subjects exposed to risk (the testing lot) and another made up of subjects that are not exposed to risk (the witness lot), each sample being representative for the chosen cohort. • Then the investigator supervises the two groups, waiting for the occurrence of either disease or death. • This model is recommended when the frequency of the risk factor is low in the population. 24. Type 2 model Contingency table of the “2x2” type: The risk factor The disease Total + - + a b a+b - c d c+d Total a+c b+d a+b+c+d • where: • a = persons, from those exposed, that contact the disease; • b = persons, from those exposed, that do not contact the disease; • c = persons, from those not exposed, that contact the disease; • d = persons, from those not exposed, that do not contact the disease; • a+b = total of exposed persons; • c+d = total of un-exposed persons; • a+c = the total of ill people; • b+d = the total of people who are not ill; 26. Risk measuring • - the risk of disease (death) at the exposed persons • -the risk of disease (death) at the persons who are not exposed 27. Risk measuring • The relative risk shows how many times is the risk of disease or death higher to the exposed than to the unexposed persons. • The attributable risk shows how many times is the risk of disease or death higher to the exposed than to the unexposed persons . It measures the excess of risk at the exposed persons, namely the percentage from the risk that is attributable to the risk factor. • The force of the epidemiological force is measured with the relative risk. 28. The relative risk • May gain values: – Equal to 1: there is no association between the risk factor and the disease for the risk is the same for both exposed and unexposed persons – Higher than 1 – there is some association between the risk factor and the disease because the risk is higher at the exposed persons. The higher than 1 the RR is, the stronger the association. – Lower than 1: the studied factor is not a risk, but a protection factor, because the risk of disease at the exposed persons is lower than in the case of the unexposed persons. 29. Proving the epidemiologic association • In order to prove the epidemiologic association between the risk factor and the disease: – the relative risk should be higher than 1 – The relative risk should be statistically significant • an X2 test of statistic significance is applied 29 • the confidence interval is determined. 30. The impact of the risk factor action in the population • Is measured with the help of the attributable risk in a population (the attributable fraction of risk in the population). • The attributable fraction of risk in a population presents interest for the public health administrator, so as to elaborate intervention strategies for the control of diseases in populations. 31. The analysis of results is done in accordance with the following table Confidence intervals are established for each risk Relative risk Attributable risk Conclusion RR > 1 AR > 0 Risk factor RR = 1 AR = 0 Indifferent factor RR < 1 AR < 0 Protection factor 32. CASE STUDIES - CONTROL 33. OBJECTIVES • Describing the essential characteristics of the case-control study model • Discussing the following methodological problems of the case-control study: – selection of cases and witnesses, – definitions of exposure and of the disease, – possible sources of data 34. THE COHORT STUDY • Subjects are selected in terms of the exposure criterion • Begins with exposure • It always has a forward direction • Exposure ------> Disease • Temporality • Prospective : “real time" • Retrospective: “historical time" 34. PROSPECTIVE COHORT STUDIES • The disease has not appeared yet, at the beginning of the study • Exposure The beginning of the study Disease • Movement from exposure towards the disease, through the “real time” • The disease is visible in the present, at the same time with he calendar time 35. HISTORIC (RETROSPECTIVE) COHORT STUDIES • The disease is already present at the beginning of the study • Exposure Disease The beginning of the study • The direction continues to be forward, moving from exposure towards the disease • Movement from exposure towards the disease through the “historic time” • The disease was present in the past, not concurrently with the calendar time 37. Model 38. CASE-CONTROL STUDIES DIAGRAM Cases E+ Population Source B+ E- Witnesses E+ B- E- 39. Measuring association
30 The frequency of the risk factor to the group of cases he frequency of the risk factor to the control group The association force is measured with the relative risk (see cohort investigations) : 40. Measuring association To prove the association force, the estimated relative risk can be used (odds ratio) which represents the ratio between two probabilities: The odds ratio is similar to the relative risk. In case of rare diseases, it can be demonstrated that a/ (a+b) and c/(c+d) are very low values, and the relative risk can me estimated by the OR: Attributable risk: The impact of the risk factor in a population is measured with the attributable risk in a population: • where: • P0= the prevalence of exposure to witnesses (the control group) • P = the prevalence of exposure in the general population 41. CONTROL-CASE MEASURING ASSOCIATION • Think of the probability report (OR)! • The probability report – Estimator of the relative risk – The probability of exposure to cases as compared to the probability of exposure to witnesses – It is also known as the exposure probabilities ratio • · Interpretation: • OR = 1 – no association • OR > 1 - E is a risk factor • OR < 1 - E est. protection factor 42. COMPARE THE DIFFERENT MEASURNGS OF THE ASSOCIATIN IN THE EXAMPLE • The risk ratio (RR) = 2,1 • The rates ratio (RR) = 2,5 • The probabilities ratio = 3,2 43. EXPERIMENTAL AND OPERATIONAL EPIDEMIOLOGIC INVESTIGATIONS Domains • 1.Evaluating the efficiency of new vaccines in protecting the population against transmissible diseases. • 2.Experimentation with the view of introducing some new drugs in the medical practice, after these have been tested in laboratories and on experimental animals. 44. Experimental epidemiologic investigations Differences from analytical investigations: a. In experimental epidemiology, the risk factor is controlled by the epidemiologist. b. The making of both the witness and the test group is easier in experimental epidemiology, as compared to the analytical epidemiology. 45. The administration of risk or protection factors • In case of the “blind” or the “simple blind” method, 2 identical groups are chosen; these receive the active product and the placebo, respectively. The persons who conduct the experiment know which of the 2 products is the active one, but the persons in the two groups are unaware of this.
31 • There can be 2 groups of errors: • - the attention with which the evaluator monitors the 2 groups differs, meaning that he/she watches more carefully the test group, situation that can be perceived by the persons making up the two groups; on the other hand, the evaluator might not see certain aspects that appear in the witness group (which is considered “less interesting by the evaluator”); • - the way of writing and presenting the results obtained after the evaluation of the two groups is definitely influenced by the fact that the person conducting the experiment knows which of the two is the active product, as well as the effects that can be expected. 46. The administration of the risk or the protection factor • in the “double blind” experiment, neither the groups, nor the evaluator know which is the active product and which is the placebo. The evaluator receives products with similar packaging, but which have different series numbers.In experimentul “dublu orb”, nici loturile si nici experimentatorul nu cunosc care este produsul activ si care este placebo-ul. Experimentatorul primeşte produsele in ambalaje identice, dar care au numere de serie diferite. In momentul când comunica rezultatele, indica si numărul de serie al produsului administrat, si numai conducătorul experimentului este in măsura sa separe fisele cazurilor care au primit produsul activ de cele ale cazurilor cărora li s-a administrat placebo-ul. 47. The general set up of an experimental epidemiological investigation 1. two sample groups of subjects are chosen, which should be as similar as possible; 2. the witness group is given a product with similar qualities, but without the active component (placebo); 3. the test lot is given the active product (risk factor, protection factor); 4. the “double blind” method is preferred, though the “blind” or even the simple method can be chosen during the administration of the product, when the subjects know the active factor; 5. results are written and the risk of disease (death) at exposed and unexposed subjects is calculated (in accordance with the methodology presented at the analytical investigations section); the relative risk and the attributable risk are also calculated; these procedures are followed by the interpretation and the analysis of the values obtained (see example 1); 6. the statistical testing of the differences obtained is done 7. the epidemiological inference is obtained
1. LECTURE 5. PROMOTING HEALTH AND PREVENTING DISEASES
2.The promotion of health and the prevention of diseases (I) The constant modification of mortality and morbidity, throughout time and in different countries, indicates the fact that the majority of diseases may be prevented. Other proofs connected to this fact result from the geographical variation of disease frequency within each country and among countries, and from the observation that immigrants gradually develop the pathologies that characterise the host population. Health promotion aims to offer the population a positive understanding of health, so that people can make use of their entire physical, mental and emotional abilities.
3.Health promotion and the prevention of diseases (II) The word prevention has seen an update in recent years, becoming a predominant concern for many societies and governments.
32 Prevention refers to the entire set of measures adopted by individuals, families, societies and states, with the view of promoting and protecting health, of preventing diseases and their consequences, and of avoiding premature deaths. In clinical medicine, the concept of prevention is also associated with the syntagm preventive medicine. 4/5.Factors that determined the updating of prophylaxis: 1. The observation that the new, peak medical technologies, and the development of the over- specialized medicine did not have the expected effect, that of improving the health state of the population. 2. The expenses for health protection increased dramatically, more than the gross national products of countries, but the outcomes in the field of health were not as expected in relation to the measure of the investments. Countries could no longer meet the growth in age-related expenditures, the increase of survival in patients with chronic diseases, factors that led to the increase of medical care volume and expenses. 3. Some improvements in the health state of the population appeared before the introduction of some very expensive technologies (thus it is supposed that other factors than the medical ones contributed to the improvement of the health state). 4. Differences in relation to the health state of populations in different geographic or socio- economic areas, modern medicine proving to have no satisfactory influence. 6.The main objectives of preventive medicine To give life to the years (through measures aimed at the control of morbidity and incapacity); To give health to life (through health promotion); To give years to life (by reducing the number of premature deaths and increasing the average lifespan). 7.The development of the health-promotion concept The evolution of the concept and its principles is the result of several conferences organized by the WHO: Ottawa1986 Adelaide 1989 Sundsvall 1993 Jakarta1997 Mexico City 2000 Bangkok 2005 8.THE OTTAWA CHARTER 1986 According to the Ottawa Charter, health is created and enjoyed by people in places where they activate daily: the place where they learn, work, play or love. 9.THE LJUBLJANA DATA SHEET (1996) Choosing viable methods for financing health-assistance services Limiting costs De-centralization Taking into account citizens’ opinions and their right to choose Improving the health state 10.NATIONAL STRATEGIES 1. Favorable circumstances:
33 A stable ecosystem and viable conditions Safe buildings, with conditions favorable to health Healthy food Appropriate educational level Appropriate revenues Social justice and equity 2. The implication of the entire community 3. The beginning of health-systems reform 11.ORGANIZATION AND INFRASTRUCTURE Creating and supporting health-promotion centers Creating and supporting local teams that work in the field of health promotion Defining the competences and qualifications related to health promotion Developing an adequate educational system ACTIVITIES 12.EDUCATIONAL AND PROFESSIONAL TRAINING THROUGH MEASURES RELATED TO: food alcohol, tobacco and drug consumption physical exercise mental health sexual behavior intake of drugs
13.HEALTH PROMOTION - DEFINITION “sustain, support in order to determine progress, develop” (DEX) “Activities for improvement or constant development in a certain field” (the Webster Dictionary) Ancient Greece India China Western Europe WHO 1946 Dubos 1968 14.Promotion and prevention: a lifelong approach 15The health-promotion logo (WHO) 18./22WHO Principles for Health Promotion The initiatives for the promotion of health should be planned and implemented in accordance with the following principles: Empowerment: The initiatives for the promotion of health should allow individuals and communities to have a greater power over personal, socio-economic and environmental factors, which influence their health. Participation: Initiatives for health promotion should involve all those concerned with the stages of planning, implementation and evaluation. Holistic approach: Initiatives for health promotion should stimulate physical, mental, social and spiritual health.
34 Inter-sector Approach: Initiatives for health promotion should involve the collaboration among agencies from different sectors of activity. Equity: Initiatives for health promotion should be guided by equity and social justice. Support: Initiatives for health promotion should determine changes that are preserved at both the individual and the community level, after the ceasing of the initial funding. Multiple strategy: Initiatives for health promotion should use, in different combinations, varied approaches, including the development of certain policies, organizational changes, community development, legislation, advocacy, education and communication.
23.The Ottawa Charter identifies three basic strategies for health promotion: Advocacy in favor of health, in order to create ideal conditions for health (peace, adequate economic resources, food and housing, stable ecosystem, intense use of resources) The empowerment of all people to achieve their full health potential Mediation among different interests of society in pursuing health 24.Priority actions, as established by the Ottawa Charter: • Creation of public-health policies • Creation of support environments • Strengthening community action for health • Developing personal abilities • Reorientation of health services 25.Creating Public Health Policies (examples): - Mobilization of all community sectors in order to enable healthy choices related to food, in places such as: workplaces, sport centres and school canteens. - Reducing public facilities costs for physical activities, by bringing them to the “reach” of children, youth and families. - Support in order to ensure the availability of quality food at affordable prices in rural or isolated areas through: - collaboration with local traders - establishment of local association for ensuring food
26.The Jakarta Declaration, July 1997 the multilateral approach to health development is the most efficient one there is a higher efficiency when the 5 priority actions, established by the Ottawa Charter, are used concomitantly health units provide practical opportunities for the implementation of comprehensive strategies participation – essential element; people should be at the centre of health-promotion actions and of decision-making processes culture/education in the field of health enhances participation; the access to education and information is essential for the effective participation and responsibility of people and communities. 27.The Jakarta Declaration – priorities: promoting social responsibility for health increasing investments for health development extending partnerships for health promotion increasing capacity at the community level and of responsibility at the individual level ensuring the infrastructure for health promotion
35 28.Places for health promotion: Educational units Families The workplace Health centers Communities Healthy cities – the first WHO project, initiated in 1986. 29. Interventions in health promotion Individual Populational Screening InformationEducation Social OrganizationalCommunityEconomic The concerning for health Marketingdevelopment action and evaluationhealth Counseling regulatory of and abilities activities individual development risk
Medical approach
Behavioral approach
Social and environmental approach
30/32Bangkok – the 6th Global Conference on Health Promotion, August 2005 The Bangkok Charter addresses to persons, groups and organizations that are essential for health: • governments and politicians from all the levels • the civil society • the private sector • international organizations • the community of specialists in public health. The global context for health promotion has changed dramatically after the Ottawa Conference. Some of the critical factors currently influencing health are: • greater inequalities among countries and within countries • the adoption of new consumption and communication models • the globalization of commerce • changes in the environment • urbanization. Key commitments Health promotion: will become a central element on the global development agenda will become the main responsibility of all governments will become a key element for civil communities and societies will become a demand for corporative good practice
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