Establishing Research Priorities in Etiologic Epidemiology

PURPOSE: A major goal of epidemiology is to discover the causes of disease in populations. The aim of this study was to develop a method for establishing research priorities within this very broad area of scientific inquiry. METHODS: While the approach is applicable to many diseases, cancer was used here, in part because of its importance to both individuals and governments. Measures of disease were estimated from data in the Ontario Cancer Registry, and combined to yield a single assessment of impact for each cancer site. Measures of exposure prevalence were identified from recent population health surveys. Cross-classification by disease and exposure rankings yielded a matrix of scores of “relative importance” for each cancer-exposure combination. Onto this matrix was overlaid: 1) estimates of statistical power for examining each association; 2) biological plausibility of each association; and 3) strength of the epidemiological evidence supporting each association. RESULTS: The disease-exposure matrix, viewed in light of statistical power, biological plausibility, and current epidemiological evidence, yielded, in the examples shown, some potentially interesting yet understudied associations (e.g., non-Hodgkin lymphoma (NHL) and certain aspects of dietary intake). CONCLUSIONS: The associations identified within the research hierarchy suggest not only new avenues for etiologic research, but also priorities for research focus.