Meta-analysis of epidemiologic dose-response data.

We discuss methods for summarizing epidemiologic studies of dose-response. The data from such a study typically appear as a series of dose-specific relative risks, with one category serving as the common reference group. We present methods for estimating the dose-response parameters from single and multiple study reports, for assigning levels to exposure categories when modeling relative risks, and for investigating the effects of study design and subject characteristics on dose-response curves. Finally, we discuss the choice of fixed vs random effects models. We illustrate our points with data from case-control studies of the relation between duration of oral contraceptive use and risk of breast cancer.