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.
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.
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.
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.