Rationale and design of CASPER: compliance and quality of life study comparing once-daily carvedilol CR and twice-daily carvedilol IR in patients with heart failure.

Adherence to a complex medical regimen in patients with chronic heart failure is an important problem. In the Medicare population, patients with heart failure take an average of 7-8 distinct medications that require >11 separate doses on a daily basis. Nonadherence to these regimens accounts for a significant proportion of hospital admissions. Simplification of the medical regimen for patients with heart failure is likely to be associated with improved adherence and, in parallel, may lead to greater satisfaction and potentially improved outcomes. Therefore, the Compliance and Quality of Life Study Comparing Once-Daily Controlled-Release Carvedilol CR and Twice-Daily Immediate-Release Carvedilol IR in Patients with Heart Failure (CASPER) trial has been designed to rigorously test the hypothesis that a once-daily formulation of carvedilol will result in better compliance and increased patient satisfaction relative to the twice-daily formulation. The background, methods, and statistical approaches used in this trial are reviewed in this article.