Distinguishing case series from cohort studies

Dekkers, Olaf M; Egger, Matthias; Altman, Douglas G; Vandenbroucke, Jan P (2012). Distinguishing case series from cohort studies. Annals of internal medicine, 156(1 Pt 1), pp. 37-40. Philadelphia, Pa.: American College of Physicians 10.1059/0003-4819-156-1-201201030-00006

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Case series are a commonly reported study design, but the label "case series" is used inconsistently and sometimes incorrectly. Mislabeling impairs the appropriate indexing and sorting of evidence. This article tries to clarify the concept of case series and proposes a way to distinguish them from cohort studies. In a cohort study, patients are sampled on the basis of exposure and are followed over time, and the occurrence of outcomes is assessed. A cohort study may include a comparison group, although this is not a necessary feature. A case series may be a study that samples patients with both a specific outcome and a specific exposure, or one that samples patients with a specific outcome and includes patients regardless of whether they have specific exposures. Whereas a cohort study, in principle, enables the calculation of an absolute risk or a rate for the outcome, such a calculation is not possible in a case series.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Social and Preventive Medicine

UniBE Contributor:

Egger, Matthias


600 Technology > 610 Medicine & health
300 Social sciences, sociology & anthropology > 360 Social problems & social services




American College of Physicians




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Date Deposited:

04 Oct 2013 14:21

Last Modified:

27 Sep 2017 07:30

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https://boris.unibe.ch/id/eprint/7286 (FactScience: 212483)

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