Glossary of Epidemiology Terms
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Descriptive Statistics (Part 2): Interpreting Study Results
Statistical Notes II Descriptive statistics (Part 2): Interpreting study results A Cook and A Sheikh he previous paper in this series looked at ‘baseline’. Investigations of treatment effects can be descriptive statistics, showing how to use and made in similar fashion by comparisons of disease T interpret fundamental measures such as the probability in treated and untreated patients. mean and standard deviation. Here we continue with descriptive statistics, looking at measures more The relative risk (RR), also sometimes known as specific to medical research. We start by defining the risk ratio, compares the risk of exposed and risk and odds, the two basic measures of disease unexposed subjects, while the odds ratio (OR) probability. Then we show how the effect of a disease compares odds. A relative risk or odds ratio greater risk factor, or a treatment, can be measured using the than one indicates an exposure to be harmful, while relative risk or the odds ratio. Finally we discuss the a value less than one indicates a protective effect. ‘number needed to treat’, a measure derived from the RR = 1.2 means exposed people are 20% more likely relative risk, which has gained popularity because of to be diseased, RR = 1.4 means 40% more likely. its clinical usefulness. Examples from the literature OR = 1.2 means that the odds of disease is 20% higher are used to illustrate important concepts. in exposed people. RISK AND ODDS Among workers at factory two (‘exposed’ workers) The probability of an individual becoming diseased the risk is 13 / 116 = 0.11, compared to an ‘unexposed’ is the risk. -
Risk Factors Associated with Maternal Age and Other Parameters in Assisted Reproductive Technologies - a Brief Review
Available online at www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2017, 8(2):15-19 ISSN : 0976-8610 CODEN (USA): AASRFC Risk Factors Associated with Maternal Age and Other Parameters in Assisted Reproductive Technologies - A Brief Review Shanza Ghafoor* and Nadia Zeeshan Department of Biochemistry and Biotechnology, University of Gujrat, Hafiz Hayat Campus, Gujrat, Punjab, Pakistan ABSTRACT Assisted reproductive technology is advancing at fast pace. Increased use of ART (Assisted reproductive technology) is due to changing living standards which involve increased educational and career demand, higher rate of infertility due to poor lifestyle and child conceivement after second marriage. This study gives an overview that how advancing age affects maternal and neonatal outcomes in ART (Assisted reproductive technology). Also it illustrates how other factor like obesity and twin pregnancies complicates the scenario. The studies find an increased rate of preterm birth .gestational hypertension, cesarean delivery chances, high density plasma, Preeclampsia and fetal death at advanced age. The study also shows the combinatorial effects of mother age with number of embryos along with number of good quality embryos which are transferred in ART (Assisted reproductive technology). In advanced age women high clinical and multiple pregnancy rate is achieved by increasing the number along with quality of embryos. Keywords: Reproductive techniques, Fertility, Lifestyle, Preterm delivery, Obesity, Infertility INTRODUCTION Assisted reproductive technology actually involves group of treatments which are used to achieve pregnancy when patients are suffering from issues like infertility or subfertility. The treatments can involve invitro fertilization [IVF], intracytoplasmic sperm injection [ICSI], embryo transfer, egg donation, sperm donation, cryopreservation, etc., [1]. -
Clarifying Questions About “Risk Factors”: Predictors Versus Explanation C
Schooling and Jones Emerg Themes Epidemiol (2018) 15:10 Emerging Themes in https://doi.org/10.1186/s12982-018-0080-z Epidemiology ANALYTIC PERSPECTIVE Open Access Clarifying questions about “risk factors”: predictors versus explanation C. Mary Schooling1,2* and Heidi E. Jones1 Abstract Background: In biomedical research much efort is thought to be wasted. Recommendations for improvement have largely focused on processes and procedures. Here, we additionally suggest less ambiguity concerning the questions addressed. Methods: We clarify the distinction between two confated concepts, prediction and explanation, both encom- passed by the term “risk factor”, and give methods and presentation appropriate for each. Results: Risk prediction studies use statistical techniques to generate contextually specifc data-driven models requiring a representative sample that identify people at risk of health conditions efciently (target populations for interventions). Risk prediction studies do not necessarily include causes (targets of intervention), but may include cheap and easy to measure surrogates or biomarkers of causes. Explanatory studies, ideally embedded within an informative model of reality, assess the role of causal factors which if targeted for interventions, are likely to improve outcomes. Predictive models allow identifcation of people or populations at elevated disease risk enabling targeting of proven interventions acting on causal factors. Explanatory models allow identifcation of causal factors to target across populations to prevent disease. Conclusion: Ensuring a clear match of question to methods and interpretation will reduce research waste due to misinterpretation. Keywords: Risk factor, Predictor, Cause, Statistical inference, Scientifc inference, Confounding, Selection bias Introduction (2) assessing causality. Tese are two fundamentally dif- Biomedical research has reached a crisis where much ferent questions, concerning two diferent concepts, i.e., research efort is thought to be wasted [1]. -
Continuous Time Individual-Level Models of Infectious Disease: Epiilmct
Continuous Time Individual-Level Models of Infectious Disease: EpiILMCT Waleed Almutiry Vineetha Warriyar K V Rob Deardon Qassim University Uinversity of Calgary University of Calgary Abstract This paper describes the R package EpiILMCT, which allows users to study the spread of infectious disease using continuous time individual level models (ILMs). The package provides tools for simulation from continuous time ILMs that are based on either spatial demographic, contact network, or a combination of both of them, and for the graphical summarization of epidemics. Model fitting is carried out within a Bayesian Markov Chain Monte Carlo (MCMC) framework. The continuous time ILMs can be implemented within either susceptible-infected-removed (SIR) or susceptible- infected-notified-removed (SINR) compartmental frameworks. As infectious disease data is often partially observed, data uncertainties in the form of missing infection times - and in some situations missing removal times - are accounted for using data augmentation techniques. The package is illustrated using both simulated and an experimental data set on the spread of the tomato spotted wilt virus (TSWV) disease. Keywords: EpiILMCT, infectious disease, individual level modelling, spatial models, con- tact networks, R. 1. Introduction Innovative mathematical and mechanistic approaches to the modelling of infectious dis- eases are continuing to emerge in the literature. These can be used to understand the spread of disease through a population - whether homogeneous or heterogeneous - and enable researchers to construct predictive models to develop control strategies to disrupt arXiv:2006.00135v1 [stat.AP] 30 May 2020 disease transmission. For example, Deardon et al. (2010) introduced a class of discrete time individual-level models (ILMs) which incorporate population heterogeneities by modelling the transmission of disease given various individual-level risk factors. -
The Basic Reproduction Number As a Predictor for Epidemic Outbreaks in Temporal Networks
The basic reproduction number as a predictor for epidemic outbreaks in temporal networks Petter Holme1,2,3 and Naoki Masuda4 1Department of Energy Science, Sungkyunkwan University, 440-746 Suwon, Korea 2IceLab, Department of Physics, Umeå University, 90187 Umeå, Sweden 3Department of Sociology, Stockholm University, 10961 Stockholm, Sweden 4Department of Engineering Mathematics, University of Bristol, BS8 1UB, Bristol, UK E-mail address: [email protected] Abstract The basic reproduction number R₀—the number of individuals directly infected by an infectious person in an otherwise susceptible population—is arguably the most widely used estimator of how severe an epidemic outbreak can be. This severity can be more directly measured as the fraction people infected once the outbreak is over, Ω. In traditional mathematical epidemiology and common formulations of static network epidemiology, there is a deterministic relationship between R₀ and Ω. However, if one considers disease spreading on a temporal contact network—where one knows when contacts happen, not only between whom—then larger R₀ does not necessarily imply larger Ω. In this paper, we numerically investigate the relationship between R₀ and Ω for a set of empirical temporal networks of human contacts. Among 31 explanatory descriptors of temporal network structure, we identify those that make R₀ an imperfect predictor of Ω. We find that descriptors related to both temporal and topological aspects affect the relationship between R₀ and Ω, but in different ways. Introduction The interaction between medical and theoretical epidemiology of infectious diseases is probably not as strong as it should. Many results in the respective fields fail to migrate to the other. -
Epidemic Models
Chapter 9 Epidemic Models 9.1 Introduction to Epidemic Models Communicable diseases such as measles, influenza, and tuberculosis are a fact of life. We will be concerned with both epidemics, which are sudden outbreaks of a disease, and endemic situations, in which a disease is always present. The AIDS epidemic, the recent SARS epidemic, recurring influenza pandemics, and outbursts of diseases such as the Ebola virus are events of concern and interest to many peo- ple. The prevalence and effects of many diseases in less-developed countries are probably not as well known but may be of even more importance. Every year mil- lions, of people die of measles, respiratory infections, diarrhea, and other diseases that are easily treated and not considered dangerous in the Western world. Diseases such as malaria, typhus, cholera, schistosomiasis, and sleeping sickness are endemic in many parts of the world. The effects of high disease mortality on mean life span and of disease debilitation and mortality on the economy in afflicted countries are considerable. We give a brief introduction to the modeling of epidemics; more thorough de- scriptions may be found in such references as [Anderson & May (1991), Diekmann & Heesterbeek (2000)]. This chapter will describe models for epidemics, and the next chapter will deal with models for endemic situations, but we begin with some general ideas about disease transmission. The idea of invisible living creatures as agents of disease goes back at least to the writings of Aristotle (384 BC–322 BC). It developed as a theory in the sixteenth century. The existence of microorganisms was demonstrated by van Leeuwenhoek (1632–1723) with the aid of the first microscopes. -
Commentary Inducing Autoimmune Disease to Treat Cancer
Proc. Natl. Acad. Sci. USA Vol. 96, pp. 5340–5342, May 1999 Commentary Inducing autoimmune disease to treat cancer Drew M. Pardoll Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196 For many years, visions for development of successful immu- colleagues (6) discovered that the target for a melanoma- notherapy of cancer revolved around the induction of immune specific CD81 T cell clone grown from a melanoma patient was responses against tumor-specific ‘‘neoantigens.’’ However, as wild-type tyrosinase, a melanosomal enzyme selectively ex- demonstrated in a recent paper in the Proceedings by Overwijk pressed in melanocytes and responsible for one of the steps in et al. (1), the generation of tissue-specific autoimmune re- melanin biosynthesis. Subsequently, a number of investigators sponses represents an approach to cancer immunotherapy that found that their melanoma-specific CD81 T cells indeed is gaining momentum. Thus, a new principle in cancer therapy recognized melanocyte-specific antigens rather than melano- states that the ability to induce tissue-specific autoimmunity ma-specific antigens (7–10). Most of these antigens appear to will allow for the treatment of many important cancers. be melanosomal proteins, and a number of them, including The original focus on tumor-specific neoantigens derived tyrosinase, TRP-1, TRP-2, and gp100, are involved in melanin from a number of findings. Vaccination-challenge experiments biosynthesis. Other melanosomal proteins such as MART1y performed between carcinogen-induced murine tumor models Melan A have no known function but are nonetheless mela- typically demonstrated that autologous tumors vaccinated nocyte-specific tissue differentiation antigens. -
Clustering of Susceptible Individuals Within Households Can Drive an Outbreak: an Individual-Based Model Exploration
medRxiv preprint doi: https://doi.org/10.1101/2019.12.10.19014282; this version posted December 14, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . Clustering of susceptible individuals within households can drive an outbreak: an individual-based model exploration Elise Kuylen1,2,*, Lander Willem1, Jan Broeckhove3, Philippe Beutels1, and Niel Hens1,4 1Centre for Health Economics Research and Modelling Infectious Diseases (CHERMID), Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium 2Discipline Group Computer Sciences, Hasselt University, Hasselt, Belgium 3IDLab, Department of Mathematics and Computer Science, University of Antwerp, Antwerp, Belgium 4I-BioStat, Data Science Institute, Hasselt University, Hasselt, Belgium *[email protected] ABSTRACT When estimating important measures such as the herd immunity threshold, and the corresponding efforts required to eliminate measles, it is often assumed that susceptible individuals are uniformly distributed throughout populations. However, unvaccinated individuals may be clustered in a variety of ways, including by geographic location, by age, in schools, or in households. Here, we investigate to which extent different levels of within-household clustering of susceptible individuals may impact the risk and persistence of measles outbreaks. To this end, we apply an individual-based model, Stride, to a population of 600,000 individuals, using data from Flanders, Belgium. We compare realistic scenarios regarding the distribution of susceptible individuals within households in terms of their impact on epidemiological measures for outbreak risk and persistence. -
Lesson 1 Introduction to Epidemiology
Lesson 1 Introduction to Epidemiology Epidemiology is considered the basic science of public health, and with good reason. Epidemiology is: a) a quantitative basic science built on a working knowledge of probability, statistics, and sound research methods; b) a method of causal reasoning based on developing and testing hypotheses pertaining to occurrence and prevention of morbidity and mortality; and c) a tool for public health action to promote and protect the public’s health based on science, causal reasoning, and a dose of practical common sense (2). As a public health discipline, epidemiology is instilled with the spirit that epidemiologic information should be used to promote and protect the public’s health. Hence, epidemiology involves both science and public health practice. The term applied epidemiology is sometimes used to describe the application or practice of epidemiology to address public health issues. Examples of applied epidemiology include the following: • the monitoring of reports of communicable diseases in the community • the study of whether a particular dietary component influences your risk of developing cancer • evaluation of the effectiveness and impact of a cholesterol awareness program • analysis of historical trends and current data to project future public health resource needs Objectives After studying this lesson and answering the questions in the exercises, a student will be able to do the following: • Define epidemiology • Summarize the historical evolution of epidemiology • Describe the elements of a case -
Unlocking the Power of Pharmacovigilance* an Adaptive Approach to an Evolving Drug Safety Environment
Unlocking the power of pharmacovigilance* An adaptive approach to an evolving drug safety environment PricewaterhouseCoopers’ Health Research Institute Contents Executive summary 01 Background 02 The challenge to the pharmaceutical industry 02 Increased media scrutiny 02 Greater regulatory and legislative scrutiny 04 Investment in pharmacovigilance 05 The reactive nature of pharmacovigilance 06 Unlocking the power of pharmacovigilance 07 Organizational alignment 07 Operations management 07 Data management 08 Risk management 10 The three strategies of effective pharmacovigilance 11 Strategy 1: Align and clarify roles, responsibilities, and communications 12 Strategy 2: Standardize pharmacovigilance processes and data management 14 Strategy 3: Implement proactive risk minimization 20 Conclusion 23 Endnotes 24 Glossary 25 Executive summary The idea that controlled clinical incapable of addressing shifts in 2. Standardize pharmacovigilance trials can establish product safety public expectations and regulatory processes and data management and effectiveness is a core principle and media scrutiny. This reality has • Align operational activities across of the pharmaceutical industry. revealed issues in the four areas departments and across sites Neither the clinical trials process involved in patient safety operations: • Implement process-driven standard nor the approval procedures of the organizational alignment, operations operating procedures, work U.S. Food and Drug Administration management, data management, and instructions, and training -
Epidemiology of and Risk Factors for COVID-19 Infection Among Health Care Workers: a Multi-Centre Comparative Study
International Journal of Environmental Research and Public Health Article Epidemiology of and Risk Factors for COVID-19 Infection among Health Care Workers: A Multi-Centre Comparative Study Jia-Te Wei 1, Zhi-Dong Liu 1, Zheng-Wei Fan 2, Lin Zhao 1,* and Wu-Chun Cao 1,2,* 1 Institute of EcoHealth, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China; [email protected] (J.-T.W.); [email protected] (Z.-D.L.) 2 State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China; [email protected] * Correspondence: [email protected] (L.Z.); [email protected] (W.-C.C.) Received: 31 August 2020; Accepted: 28 September 2020; Published: 29 September 2020 Abstract: Healthcare workers (HCWs) worldwide are putting themselves at high risks of coronavirus disease 2019 (COVID-19) by treating a large number of patients while lacking protective equipment. We aim to provide a scientific basis for preventing and controlling the COVID-19 infection among HCWs. We used data on COVID-19 cases in the city of Wuhan to compare epidemiological characteristics between HCWs and non-HCWs and explored the risk factors for infection and deterioration among HCWs based on hospital settings. The attack rate (AR) of HCWs in the hospital can reach up to 11.9% in Wuhan. The time interval from symptom onset to diagnosis in HCWs and non-HCWs dropped rapidly over time. From mid-January, the median time interval of HCW cases was significantly shorter than in non-HCW cases. -
Understanding Risk & Protective Factors for Suicide
Understanding Risk and Protective Factors for Suicide: A Primer for Preventing Suicide Risk and protective factors play a critical role in suicide prevention. For clinicians, identifying risk and protective factors provides critical information to assess and manage suicide risk in individuals. For communities and prevention programs, identifying risk and protective factors provides direction about what to change or promote. Many lists of risk factors are available throughout the field of suicide prevention. This paper provides a brief overview of the importance of risk and protective factors as they relate to suicide and offers guidance about how communities can best use them to decrease suicide risk. Contents: What are risk and protective factors? Risk factors are not warning signs. What are major risk and protective factors for suicide? Why are risk and protective factors important? Using risk and protective factors in the strategic planning process Key points about risk and protective factors for suicide prevention Additional resources Further reading References What are risk and protective factors? Risk factors are characteristics that make it more likely that individuals will consider, attempt, or die by suicide. Protective factors are characteristics that make it less likely that individuals will consider, attempt, or die by suicide. Risk and protective factors are found at various levels: individual (e.g., genetic predispositions, mental disorders, personality traits), family (e.g., cohesion, dysfunction), and community (e.g., availability of mental health services). They may be fixed (those things that cannot be changed, such as a family history of suicide) or modifiable (those things that can be changed, such as depression).