Meta-Analysis

In epidemiology, the proliferation of multiple and sometimes contradictory studies can be a challenge [Page 673]for interpretation of health risk and health policy formulation. One approach to synthesizing the results of separate but related studies is meta-analysis—the systematic identification, evaluation, statistical synthesis, and interpretation of separate study results. For example, for many years, conflicting results were reported in observational studies of the effect of diet on breast cancer risk. The lower rate of breast cancer incidence for women in Asian countries suggested a protective effect for soy-based diets; yet migration patterns and changes in diet yielded conflicting results. A synthesis of epidemiologic studies showed a moderately protective effect for soy intake (odds ratio [OR] = 0.89, 95% confidence interval [CI] 0.75 − 0.99), with a ...