RETEPLASE MORTALITY STUDIES

It seems unlikely that new thrombolytics will lead to further large re ductions in fatality from an acute myocardial infarction, but new agen ts may well have advantages in safety, ease of administration and cost s. The problem is how to introduce such new agents without a megatrial for each one. End-points other than fatality have advantages, and in thrombolysis angiographic studies are a necessary first step in the de velopment of new agents. However, such studies can never be very large , and their results do not correlate sufficiently precisely with the r esults of mortality end-point studies for angiographic patency to be a n acceptable alternative to survival. The 'equivalence' of two treatme nts is a clinical, not a statistical, concept but statistical principl es can be applied which allow equivalence to be investigated with medi um-sized trials. Demonstrating equivalence in outcome between the new thrombolytic reteplase and streptokinase was the aim of the INJECT Stu dy; reteplase having been shown to be equivalent to streptokinase, ret eplase has been recommended for licensing by the FDA.