Thrombolysis in myocardial infarction (TIMI) randomized studies versus TIMI open label studies

Prior to each randomized study, the Thrombolysis in Myocardial Infarction (TIMI) investigators conducted pilot studies following the treatment protocols for the randomized studies except that patients in the pilot studies were systematically assigned to known treatments. The pilot studies were performed to assess the feasibility of the protocols and to allow the investigators to gain experience with the study procedures. In this report the results for several outcome measures for patients in the pilot studies are contrasted with the results for patients in two of the randomized studies, TIMI Phase I and TIMI Phase II A. The TIMI experience indicates that pilot studies are useful for assessing the feasibility of a protocol and testing study procedures and are of limited value in estimating treatment differences.