National Study on the Prevalence of Iodine Deficiency Disorders Among School Children Aged 8-12 Years Old in Bahrain
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National Study On The Prevalence of Iodine Deficiency Disorders Among School Children Aged 8-12 years old in Bahrain By Dr. Khairya Moosa Head, Nutrition Section Ministry of Health, Bahrain Dr.A.W.M. Abdul Wahab Assistant Undersecretary for Primary Care & Public Health Ministry of Health, Bahrain Dr. Jamal AlSayyad Consultant Epidemiologist Ministry of Health, Bahrain Dr. Bader Z. Hassan Baig Head, Public Health Laboratory Ministry of Health, Bahrain 2000 Table of Contents Subject Page No. Acknowledgements 2 Abstracts 3 Introduction 4 Aim of the study 4 Specific Objectives 5 Subjects & Methods 5 Results 10 Discussion and Recommendations 11 References 24 Appendix 26 1 Acknowledgements This study was partially supported by Joint Ministry of Health and World Health Organization Regional Office (JPRM) fund. The staff of the nutrition section (Ms. Ghada Al-Raees, Mrs. Manal Al- Sairafi and Mrs. Mariam Al-Amer) have cooperated and assisted fully in the field work, data entry and analysis. We are indebted to Dr. Mohammed Rafie, General Surgeon at Salmaniya Medical Complex for his cooperation in conducting neck examination at schools. Sincere thanks to the Ministry of Education officials and school administrators for their support and cooperation. 2 Abstract Background Iodine deficiency disorder (IDD) Continues to be an important public health problem in many countries. In the Eastern Mediterranean Region, 348 million (74% of the population) are considered to be at risk of iodine deficiency. The main objective of this study was to estimate the prevalence of goitre and iodine deficiency among school children in Bahrain. Methods A cross-sectional survey of primary school children was carried out. A total of 1600 children were chosen at random from all government schools using the multistage cluster sampling method. Selected children were examined for goitre by a surgeon and 50% of them were chosen at random for urinary iodine level assessment. Prevalence estimates of goitre and IDD (mild, moderate, severe) was illustrated according to age, sex and area of residence. Results Out of 1600 children examined, only 26 (1.7%) were found to have goitre. On the other hand, 121 out of 749 (16.5%) children tested had low urinary iodine levels. This prevalence of IDD was slightly lower for boys (15.8%) compared to girls (16.5%), and showed some geographic variation. Conclusions IDD does not seem to constitute a public health problem in Bahrain, yet IDD is affecting some children. Health education can help in increasing public awareness about the nutritional value of iodized salts in the prevention of this disorder in order to maintain this low level and to ensure that IDD remains under control.. 3 1- Introduction Iodine is an essential element for human survival. It is needed for growth and development, even before birth 1 . Although iodine is an important micronutrient, it is needed only in very small quantities. In order to prevent deficiency, a person needs only 250 µg of iodine per day, and over a lifetime, the total quantity of iodine needed is only one teaspoonful 2 . Healthy humans require iodine, which is an essential component of the thyroid hormones. Failure to have adequate iodine leads to insufficient production of these hormones, which affect many different parts of the body, resulting in a number of pathologic conditions known as the Iodine Deficiency Disorders (IDD) 2. Iodine deficiency continues to be a significant public health problem in many countries, it’s deficiency not only causes goiter, it may also result in abortion, stillbirth, mental retardation, growth retardation, irreversible brain damage and retarded psychomotor development in the fetus, infant and in the child. It also affects reproductive functions and impedes children’s learning ability 3. Iodine deficiency is now recognized as the most common preventable cause of brain damage in the world today 4. Of WHO’s 191 member states, 130 are affected by IDD. At least 2,225 million people, live in iodine deficient environments and are thus at risk of IDD, and at least 740 million of these (13%) are considered to be affected by goiter. The highest regional prevalence is the Eastern Mediterranean Region (32%), and in this region about 348 million (74%) of the population is considered to be at risk of iodine deficiency 5. As far as we are aware, no previous attempt has been made to study the prevalence of IDD in Bahrain. Therefore, we have conducted this national epidemiological survey among Bahraini school children aged 8-12 years old for assessing the iodine status in Bahrain, through clinical assessment of thyroid gland, and urinary iodine estimation. 2- Aim of the study Data regarding Iodine Deficiency Disorders (IDD) in Bahrain are scarce and even lacking. Therefore, this study aims at establishing baseline data for planning, monitoring and evaluating the nutrition intervention program. 4 3- Specific Objectives 1- To determine the Prevalence of Iodine Deficiency Disorders (IDD) among school children in Bahrain. 2- To determine the distribution of IDD if present, in relation to demographic characteristics. 4- Subjects & Methods: 4.1. The setting The State of Bahrain consists of several islands in the Arabian Gulf, situated 20 km. east of Saudi Arabia. The total area of Bahrain is 706 sq. km. The island is arid, receiving as low as 22 mm of rain annually 6. The population of Bahrain was 0.64 million in 1998 of whom 39.2 were expatriates, mostly from the Indian subcontinent. The population is young, with 30.9% under the age of 15 years 7. Oil and gas, aluminum products, banking, tourism, and food industries are the mainstay of the economy. In 1998, statistics indicated that the Gross Domestic Product (GDP) in US$ 8957 and the Gross National Product (GNP) in US$ 8043 7. In the past two decades, there has been a progressive change in socioeconomic development due to oil revenues. This has led to a shift in the way Bahrainis earn their livings from agriculture and fishing to sedentary jobs in the oil and service sectors. Health services in Bahrain are organized into primary, secondary and tertiary health care hospitals, including high technology medicine. Health services are provided free of charge to the population. With a view to making geographical access to health services equitable and easier, the health authorities have divided the country into four catchment areas (health regions), each with a satellite of health centers. Socio-economic conditions have improved a lot during the past years, which caused a dramatic fall in the infant mortality rate from 18 per 1000 in 1993 to 8.5 per 1000 in 1998, and an under – 5 mortality rate from 22 per 1000 in 1993 to 11.1 per 1000 in 1998. This was mainly due to the improvement of the health services provided by the country, as both primary, secondary and tertiary health care services. The maternal 5 mortality rate was 0.15 per 1000 live births in 1998, as well as a relatively high life expectation of 72.9 years in 1998. The crude birth rates and death rates during 1998 were 20.3% and 3.1% respectively 8. 4.2. Population & Sampling Design 4.2.1. Study population Children aged 8 to 11 years were the target group of this survey. This group is highly vulnerable to IDD and good representation of the group can be achieved from school attendance roster in Bahrain since the defaulter rate is considerably low. 4.2.2. Sample size Sample size was calculated using the equation N = Z2 P(1-P)/d2 where 2 Z = the standard normal deviate at confidence level 1 - ∝/ P = the prevalence of IDD d = absolute precision Based on 50% prevalence of IDD (in order to maximize the sample size), 95% confidence limits and 5% absolute precision, the sample size was calculated to be 384. This was multiplied by 4 (bringing the sample size up to 1536) to allow for design effect due to application of cluster sampling method as recommended by Lawaya and Lemeshow 9. The ultimate sample size required for the study was determined at 1600 children. 4.2.3. Sampling method Multi-stage cluster sampling technique was applied to select 40 children from each of 40 cluster schools chosen at random as follows :- a. A list showing names of all government boys and girls primary schools, the number of students in each school and the cumulative number of students was prepared. b. The total number of students in all of the schools was 27453. This was divided by 40 to obtain the cluster interval (686). c. A random digit between 1 and 686 was produced. The first cluster school was the one in which the 6 corresponding cumulative number contained the random digit. d. The class interval value was added to the random digit value in point (c) and the second cluster school was the next school in which the corresponding cumulative number contained the resulting summed value. e. The following clusters were identified by keeping adding the cluster interval to the total summed value which identified the previous cluster. f. For each cluster school a list of students actually registered in the primary classes targeted by the study was obtained from the Ministry of Education. Forty children from the list were chosen by systematic random method. g. Every 2nd child interviewed in each cluster school was also chosen for the purpose of the Urine Iodine Study (i.e. 50% of the 1600 school children). 4.3. Data collection Data collection was divided into 3 main parts:- 4.3.1. Socio-demographic data: Using a pre-designed questionnaire, socio-demographic data were recorded from the student school record by nutritionists (Appendix A). 4.3.2.