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McMahon AD, MacDonald TM. Sample size for cohort studies in pharmacoepidemiology. Pharmacoepidemiol Drug Saf. 1997;6(5):331-5doi: 10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9.
McMahon, A. D., & MacDonald, T. M. (1997). Sample size for cohort studies in pharmacoepidemiology. Pharmacoepidemiology and drug safety, 6(5), 331-5. https://doi.org/10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9
McMahon, A D, and MacDonald, T M. "Sample size for cohort studies in pharmacoepidemiology." Pharmacoepidemiology and drug safety vol. 6,5 (1997): 331-5. doi: https://doi.org/10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9
McMahon AD, MacDonald TM. Sample size for cohort studies in pharmacoepidemiology. Pharmacoepidemiol Drug Saf. 1997 Sep;6(5):331-5. doi: 10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9. PMID: 15073768.
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Pharmacoepidemiol Drug Saf. 1997 Sep;6(5):331-5. doi: 10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9.

Sample size for cohort studies in pharmacoepidemiology.

Pharmacoepidemiology and drug safety

A D McMahon, T M MacDonald

Affiliations

  1. Medicines Monitoring Unit, Department of Clinical Pharmacology, University of Dundee, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK. [email protected]

PMID: 15073768 DOI: 10.1002/(SICI)1099-1557(199709/10)6:5<331::AID-PDS297>3.0.CO;2-9

Abstract

OBJECT: Cohort studies in pharmacoepidemiology can result in a unique type of study, where subjects have complex types of exposure to drugs (with periods of non-exposure as well). The object of this paper is to explain how to calculate the sample size of such a study.

METHOD: It is assumed that adverse events follow Poisson distributions in the two study groups. The null hypothesis is that the two groups have equal rates of disease. Formulae are provided to calculate the sample size required to significantly reject the null hypothesis. Sample size is given as the number of events, rather than the number of subjects entered. In a Poisson study, it is the ratio of the amount of person-years exposure in the two groups that is important to calculate sample size, rather than the actual amounts of exposure (or number of subjects in the study). Some examples are included.

Copyright 1997 John Wiley & Sons, Ltd.

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