A Policy and Data Monitoring Board was appointed to review the protocols for the pilot studies as they developed and make recommendations to the Director of NHLBI. The Policy and Data Monitoring Board reviewed the accumulated data on April 8, 1983 and recommended to the Institute that a full scale trial be implemented. The recommendation was accepted by the Director, NHLBI and was presented to the National Heart, Lung, and Blood Advisory Council at its meeting in May 1983. A full scale trial was conducted.