An advance in trial methods arose from difficulties in the statistical analysis of the FIELD diabetes trial. In this large international trial, 9795 patients were randomly assigned to fenofibrate or placebo and followed up for an average of five years. Cardiovascular outcomes were measured.
Over the five years of the trial, many patients started taking newly approved cholesterol-lowering drugs, confounding the effect of the study drug. FIELD investigators andCTCstatisticians devised a novel method using the results of other clinical trials to adjust the estimates of efficacy of the study drug, a method with potential for wide application in long-term trials.