Epidemiologic studies of rheumatoid arthritis: future directions.

We (1) review the current status of epidemiologic studies of rheumatoid arthritis (RA); (2) consider the strengths and weaknesses of such studies and (3) offer suggestions regarding directions which future work might take. We will not examine any particular studies in great detail, but, instead, will focus on those broad aspects of epidemiologic work concerning RA which seem most important. In this process, it may be useful to draw comparisons with cancer epidemiology, since etiologic possibilities in cancer often resemble those seen in RA and similar methodologic issues are involved.