The "cooperative" type of study has inherent deficiencies, such as the variability in intrepretation of clinical and laboratory findings in different institutions. The element of human error is thus magnified as the number of investigators increases. Nevertheless, this approach must occassionally be used in evaluating therapy for myocardial infarction. Certainly consideration of anticoagulant drugs requires a large number of patients for meaningful conclusions; even 1,000 patients may someday be considered an inadequate series if the present trend continues.
Heparin is recognized as an effective and safe anticoagulant agent. Moreover, newer heparin preparations can be administered with more convenience and less expense than formerly. These practical and theoretical considerations prompted the formation in 1960 of a study group to compare the relative merits of heparin and warfarin for anticoagulant therapy in acute myocardial infarction. Approximately 1,000 patients were studied during a three-year period, and 798 ultimately qualified for statistical evaluation of