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Table 1 Overview of the three self-controlled methods

From: A comparison of estimators from self-controlled case series, case-crossover design, and sequence symmetry analysis for pharmacoepidemiological studies

Methods Effect measures Study populations Information used in analysisa Main assumptions
Self-controlled case series Incident rate ratio Case patients who experienced at least one event during each observation period Every exposure and every event for each case patient Events do not alter the probability of subsequent exposure and events.
Case-crossover design (Exposure) odds ratio Case patients who experienced at least one event during each observation period Every exposure and the first event for each case patient There are no time-trends in the occurrence of exposure.
Sequence symmetry analysis Adjusted sequence ratio Case patients who experienced at least one exposure or one event during each observation period The first exposure and first event for the study population Events do not alter the probability of subsequent exposure. Trends in the occurrence of exposure and events are similar to those for the study population.
  1. aMinimal information required for the calculation of each effect measure