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Essentials of epidemiology for toxicologists

Essentials of epidemiology for toxicologists
Essentials of epidemiology for toxicologists
Epidemiology is concerned with the distribution and determinants of health in populations. The applications of epidemiology that are of most relevance to toxicology lie in the identification and characterization of toxic hazards, the assessment of risks from toxic exposures, and the evaluation of measures designed to control such risks. Most epidemiological studies focus on the occurrence of disease, but other health outcomes such as symptoms and disability may also be investigated. Incidence (the rate at which new cases of disease occur in a population) is the measure of disease frequency of most relevance to study of causation. Other measures such as mortality (the incidence of death from a disease) and prevalence (the proportion of a population who are cases at a point in time or during a specified period) may be used as a proxy for incidence, but results must then be interpreted with added care. Where disease rates vary importantly by sex and age, comparison between populations may be enhanced by use of sex- and age-specific rates, or by standardizing rates for sex and age. Various statistics are used to summarize associations between ‘risk factors’ and health outcomes, each with its particular applications. Attributable risk is relevant when making decisions in risk management for individuals. Relative risk (RR) (or the closely related odds ratio) is most useful when considering whether associations are likely to be causal. Population attributable risk and attributable proportion are useful in risk management for populations. The attributable fraction in exposed (AFexp) is used when determining causal attribution for purposes of compensation. Major considerations in the design and interpretation of epidemiological studies are bias (a systematic tendency to underestimate or overestimate a parameter of interest), chance and confounding (which occurs when the risk factor of interest is associated with a ‘confounding’ factor that independently determines the risk of developing the health outcome under study). Assessment of the potential impact of chance is helped by statistical inference using either hypothesis-testing (p-values) or confidence intervals. Categories of epidemiological investigation include descriptive studies, ecological studies, cohort studies, case–control studies, cross-sectional surveys and randomized and nonrandomized experiments. Each of these study methods has its particular applications, strengths and limitations. In addition to bias, chance and confounding, other considerations when interpreting and comparing epidemiological findings are the ways in which exposures and health outcomes have been classified, and the potential for biological modification of causal associations by ‘effect modifiers’. In addition, epidemiological results should always be viewed in the context of relevant biology, including what is known from toxicological studies in the laboratory.
epidemiology, design, interpretation, applications, risk assessment
9780470744307
Wiley
Coggon, D.
2b43ce0a-cc61-4d86-b15d-794208ffa5d3
Casciano, Daniel A.
Sahu, Saura C.
Ballantyne, Bryan
Marrs, Timothy
Syversen, Tore
Coggon, D.
2b43ce0a-cc61-4d86-b15d-794208ffa5d3
Casciano, Daniel A.
Sahu, Saura C.
Ballantyne, Bryan
Marrs, Timothy
Syversen, Tore

Coggon, D. (2009) Essentials of epidemiology for toxicologists. In, Casciano, Daniel A., Sahu, Saura C., Ballantyne, Bryan, Marrs, Timothy and Syversen, Tore (eds.) General, Applied and Systems Toxicology. Wiley. (doi:10.1002/9780470744307.gat111).

Record type: Book Section

Abstract

Epidemiology is concerned with the distribution and determinants of health in populations. The applications of epidemiology that are of most relevance to toxicology lie in the identification and characterization of toxic hazards, the assessment of risks from toxic exposures, and the evaluation of measures designed to control such risks. Most epidemiological studies focus on the occurrence of disease, but other health outcomes such as symptoms and disability may also be investigated. Incidence (the rate at which new cases of disease occur in a population) is the measure of disease frequency of most relevance to study of causation. Other measures such as mortality (the incidence of death from a disease) and prevalence (the proportion of a population who are cases at a point in time or during a specified period) may be used as a proxy for incidence, but results must then be interpreted with added care. Where disease rates vary importantly by sex and age, comparison between populations may be enhanced by use of sex- and age-specific rates, or by standardizing rates for sex and age. Various statistics are used to summarize associations between ‘risk factors’ and health outcomes, each with its particular applications. Attributable risk is relevant when making decisions in risk management for individuals. Relative risk (RR) (or the closely related odds ratio) is most useful when considering whether associations are likely to be causal. Population attributable risk and attributable proportion are useful in risk management for populations. The attributable fraction in exposed (AFexp) is used when determining causal attribution for purposes of compensation. Major considerations in the design and interpretation of epidemiological studies are bias (a systematic tendency to underestimate or overestimate a parameter of interest), chance and confounding (which occurs when the risk factor of interest is associated with a ‘confounding’ factor that independently determines the risk of developing the health outcome under study). Assessment of the potential impact of chance is helped by statistical inference using either hypothesis-testing (p-values) or confidence intervals. Categories of epidemiological investigation include descriptive studies, ecological studies, cohort studies, case–control studies, cross-sectional surveys and randomized and nonrandomized experiments. Each of these study methods has its particular applications, strengths and limitations. In addition to bias, chance and confounding, other considerations when interpreting and comparing epidemiological findings are the ways in which exposures and health outcomes have been classified, and the potential for biological modification of causal associations by ‘effect modifiers’. In addition, epidemiological results should always be viewed in the context of relevant biology, including what is known from toxicological studies in the laboratory.

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Published date: 15 December 2009
Keywords: epidemiology, design, interpretation, applications, risk assessment
Organisations: Faculty of Medicine

Identifiers

Local EPrints ID: 355607
URI: https://eprints.soton.ac.uk/id/eprint/355607
ISBN: 9780470744307
PURE UUID: b66d5559-07a1-4650-ab1c-0f4e5c25d29c
ORCID for D. Coggon: ORCID iD orcid.org/0000-0003-1930-3987

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Date deposited: 04 Sep 2013 09:17
Last modified: 06 Jun 2018 13:02

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Contributors

Author: D. Coggon ORCID iD
Editor: Daniel A. Casciano
Editor: Saura C. Sahu
Editor: Bryan Ballantyne
Editor: Timothy Marrs
Editor: Tore Syversen

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