Longitudinal trends in health-related quality of life in adults with cystic fibrosis.

Background: Health-related quality-of-life (HRQOL) measures have been used as patient-reported outcomes in clinical trials in cystic fibrosis (CF), but there are limited data on HRQOL changes over time in adults with CF.

Methods: The Project on Adult Care in Cystic Fibrosis, a prospective, longitudinal panel study of 333 adults with CF at 10 CF centers in the United States, administered a disease-specific HRQOL measure, the Cystic Fibrosis Questionnaire-Revised (CFQ-R), seven times over 21 months. The CFQ-R assesses both physical and psychosocial domains of health. Growth curve regression models were developed for each CFQ-R domain, adjusting for demographic and clinical characteristics.

Results: Between 205 and 303 adults completed surveys (response rate, 70%-93%). Mean age at baseline was 33 years (range, 19-64 years); mean FEV1 % predicted was 59.8% (SD, 22%). Over the 21 months of follow-up, lung function, frequency of pulmonary exacerbations, and nutritional indices were associated with physical CFQ-R domain scores. There were no significant population trends over time in the physical domain scores; however, there were population time trends in three psychosocial domains: treatment burden (+8.9 points/y), emotional functioning (+3.2 points/y), and social functioning (-2.4 points/y). Individual variation in both physical and psychosocial subscales was seen over 21 months.

Conclusions: In a longitudinal multicenter population of adults with CF, clinical variables such as FEV1, exacerbation frequency, and weight were correlated with related CFQ-R subscales. For the population as a whole, the physical domains of CFQ-R, such as respiratory symptoms, were stable. In contrast, population changes in several psychosocial domains of CFQ-R suggest that differentiating between the physical and the psychosocial trajectories in health among adults with CF is critical in evaluating patient-reported outcomes.