Clinically important differences in health-related quality of life for patients with asthma: an expert consensus panel report.

BACKGROUND: Standards for change in health-related quality of life (HRQoL) measures used among asthmatic patients have been established by considering only patient preferences to determine important differences and may not reflect an informed clinical evaluation of change.
OBJECTIVE: To establish clinically important difference (CID) standards through the consensus of an expert physician panel for the Juniper Asthma Quality of Life Questionnaire (AQLQ) and Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36, version 2) when used to measure HRQoL among asthmatic patients.
METHODS: We organized an 8-person panel of physicians familiar with measuring HRQoL among asthmatic patients with the AQLQ and the SF-36. This expert panel participated in 2 rounds of a modified Delphi process before attending an in-person consensus meeting to establish the CID standards for small, moderate, and large changes in the AQLQ and the SF-36. After the consensus meeting, the panel used an iterative improvement process to cooperatively complete their final report.
RESULTS: The expert panel's thresholds for detecting CIDs in the domains of the AQLQ were much higher than previously established levels using patient-perceived changes. CIDs for asthma were also ascertained on the scales of the SF-36, version 2, which were markedly greater than previously cited cross-sectional differences between patient groups.
CONCLUSIONS: The CID standards established by this expert panel elucidate a potential distinction between patient and physician perspectives of important HRQoL changes. The many stakeholders of HRQoL difference standards should consider this distinction when adopting standards to evaluate patient change.