Article Text
Abstract
The purpose of this paper is to help readers choose an appropriate observational study design for measuring an association between an exposure and disease incidence. We discuss cohort studies, sub-samples from cohorts (case-cohort and nested case-control designs), and population-based or hospital-based case-control studies. Appropriate study design is the foundation of a scientifically valid observational study. Mistakes in design are often irremediable. Key steps are understanding the scientific aims of the study and what is required to achieve them. Some designs will not yield the information required to realise the aims. The choice of design also depends on the availability of source populations and resources. Choosing an appropriate design requires balancing the pros and cons of various designs in view of study aims and practical constraints. We compare various cohort and case-control designs to estimate the effect of an exposure on disease incidence and mention how certain design features can reduce threats to study validity.
- epidemiology
- epidemiology
- public health
- statistics & research methods
- health informatics
- cardiac epidemiology
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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Footnotes
Deceased Douglas died on 3 June 2018.
Contributors MHG, DGA, SMC, GC, SJWE, PS, EW and MW conceived the contents of the study. MHG drafted the manuscript. DGA, SMC, GC, SJWE, PS, EW and MW critically reviewed and edited it. MHG, SMC, GC, SJWE, PS, EW and MW gave final approval of the version to be published and are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. DGA died during the preparation of the manuscript. MHG is the guarantor.
Funding GC was supported by the NIHR Biomedical Research Centre, Oxford; MHG was supported by the Intramural Research Programme of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.