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. 2016 Mar 22;38:676–684. doi: 10.1007/s11096-016-0285-6

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© The Author(s) 2016

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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Fig. 1 — Cohort and case control study designs. In a cohort study, subjects are classified as an exposed or non-exposed group based on their drug exposure status at study commencement. Subjects are then followed up over time to identify any occurrence of the outcome of interest. In a case–control study, subjects are classified as case and control (non-case) at study commencement. Subjects with the outcome of interest are defined as cases, while subjects without the outcome of interest are defined as controls. Information is collected retrospectively to identify any previous drug exposure