Rationale and statistical methodology for the VISA studies

After examination of the epanolol ('Visacor') clinical package it became clear that, although efficacy and safety of epanolol were equivalent to efficacy and safety with other antianginal therapies, tolerability was improved. It was decided to initiate 2 studies with 500 patients in each to quantify the improved tolerability and examine patient preference for antianginal treatments. One study was a comparison of epanolol 200mg daily with metoprolol 100mg twice a day and the other compared epanolol 200mg daily with nifedipine retard 20mg twice a day. The rationale, design and statistical methodology are presented, together with a summary of the geographical spread of the study.