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Diagram representing the study design. In this hypothetical example the patient has two exposed periods (acute exacerbation) during follow-up and a first myocardial infarction within 91 days of the start of the second exposed period (acute exacerbation). AECOPD = acute exacerbation of chronic obstructive pulmonary disease; IS = ischemic stroke; MI = myocardial infarction.
