The purpose of the study was to develop clinically important difference (CID) standards for patients with coronary artery disease and congestive heart failure that identify small, moderate, and large intraindividual changes with time in a modified version of the Chronic Heart Failure Questionnaire (CHQ) and the Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36, version 2). Prior work in ascertaining important difference standards for the CHQ have centered on patient-perceived changes. No important difference standards for the SF-36 have been published for patients with heart disease. This development of CIDs would facilitate the use of health status measures in daily clinical decision-making.

We used a modification of the RAND Appropriateness Method to assemble and guide a 9-member consensus panel of physicians with substantial experience in using the CHQ or the SF-36 among patients with heart disease.

On the basis of their own experience using these measures and an extensive review of articles describing the development and use of these instruments, the expert panel achieved consensus on small, medium, and large clinically relevant changes in scores for the CHQ and SF-36. The CID standards established by this panel were slightly higher than the minimal important difference standards previously established for the CHQ using patient-perceived changes.

The CID standards established by this expert panel provide an important and useful tool for determining whether routine clinical health status assessments will benefit patients and enhance physicians' decision-making capacity in clinical settings.