Multicenter Case-Crossover Design — Multi-Site Self-Matched Transient Exposure Study

The multicenter case-crossover design is an observational epidemiological method that investigates whether brief, transient exposures trigger acute health events by comparing each case's exposure just before the event to their own exposure during matched control periods — with data collected from two or more independent clinical or geographic sites to increase power, external validity, and the ability to detect site-level effect modification.