Abstract
BACKGROUND: Assessment of health-related quality of life (HRQL) of patients with chronic lung disease has become an important aspect of many clinical investigations. The authors examined the measurement properties of a disease-specific HRQL questionnaire, the Chronic Respiratory Questionnaire (CRQ), when used by independent investigators in clinical trials and observational studies.METHODS: All published papers citing the original 1987 CRQ publication were identified using the Science Citation Index, and abstracts presented at international conferences were found by hand search. Clinical trials and observational studies were included if they reported data bearing on the CRQ’s measurement properties.RESULTS: Of 90 papers and 20 abstracts, 32 met the inclusion criterion. CRQ domains of fatigue, mastery and emotional function have high reliability, and face, content and construct validity in differentiating among patients with better and worse HRQL. Because of its self-generated items, the dyspnea domain works less well in discriminating among patients with lesser and greater dyspnea. When CRQ has been used to evaluate treatment, all four domains have performed well in detecting small treatment effects. The minimal important difference in CRQ score (0.5 per item) provides guidance for both planning studies and interpreting results. To maximize CRQ interpretability, investigators should present results as the mean score per item within each domain on a seven-point scale.CONCLUSION: The CRQ has proved valid and responsive to change. Its standardization and continued wide use will enhance the understanding of the impact of treatments on patients’ HRQL.