INTERPRETATION AND BIAS IN CASE-CROSSOVER STUDIES

The case-crossover design is an innovative epidemiologic technique wit h distinct strengths and limitations. We review the fundamental logic of this self-matching non-randomized design and direct attention to 15 concerns related to the available data, unavailable data, analytic te chnique, quantitative statistics, and etiologic model. Implications fo r each concern are discussed in the context of a recent report on whet her cellular telephone calls are associated with an increased risk of a motor vehicle collision. We suggest that an understanding of the cas e-crossover design may help investigators explore selected questions i n behavioral medical research. (C) 1997 Elsevier Science Inc.