Clinical Trials

Clinical Trials: A Practical Guide ■❚❙❘Figure 3. Trial profile for a factorial-design study investigating the use of vitamin E and n-3 polyunsaturatedfatty acid (PUFA) supplementation in patients suffering a recent myocardial infarction [3].11,324 patients randomized2,836 givenn-3 PUFA2,830 givenvitamin E2,830 given n-3 PUFAplus vitamin E2,828 controls3 lost tofollow-up768 discontinuedn-3 PUFA4 lost tofollow-up687 discontinuedvitamin E11 receivedn-3 PUFA4 lost tofollow-up848 discontinuedn-3 PUFA808 discontinuedvitamin E2 lost tofollow-up15 receivedn-3 PUFA2 receivedvitamin E2,836 analyzedfor outcomes2,830 analyzedfor outcomes2,830 analyzedfor outcomes2,828 analyzedfor outcomesReprinted with permission from Elsevier (Lancet 1999;354:447–55).Two-way parallel designFigure 2 shows a trial profile from a two-arm parallel design study. The studyinvestigated whether the time to achieve a negative sputum culture amongpatients with newly diagnosed tuberculosis would be decreased by addingMycobacterium vaccae to standard short-course anti-tuberculosis chemotherapy.Patients were randomized to an injection of either saline (placebo) orMycobacterium vaccae [2]. This is an example of a trial profile in which theinformation on all five of the components of trial execution is clearly provided.The profile indicates that 175 patients from the placebo group and 172 patientsfrom the vaccine group were used for the primary endpoint analysis. However,safety analysis was based on 185 placebo patients and 189 vaccine patients. Thereasons for this discrepancy are described in the report [2].2 × 2 factorial designFigure 3 illustrates a 2 × 2 factorial study, which can be reported as a four-armparallel trial. This study investigated the effects of vitamin E or n-3 polyunsaturatedfatty acid (PUFA) supplementation in patients who had suffered a recentmyocardial infarction [3]. The primary combined efficacy endpoint was death,non-fatal myocardial infarction, and stroke. From October 1993 to September381