The association between depression, lung function, and health-related quality of life among adults with cystic fibrosis.

BACKGROUND More than 40% of people born with cystic fibrosis (CF) now reach adulthood. Greater attention is being focused on improving their health-related quality of life (HRQoL). While markers of disease severity such as lung function are only modestly associated with HRQoL, in other chronic illnesses depression is an important correlate. The objective of this study was to evaluate the relationships among lung function (ie, FEV(1) percent predicted), depressive symptoms, and HRQoL among adults with CF. METHODS Seventy-six adults with CF completed a mail-based survey. The Beck Depression Inventory and the Cystic Fibrosis Questionnaire were used to assess depressive symptoms and HRQoL, respectively. Values for FEV(1) percent predicted were abstracted from the medical record. RESULTS Thirty percent of participants screened positive for depressive symptoms. Depressive symptoms and lung function were inversely correlated (rho = -0.25; p < .05). Correlations between depressive symptoms and HRQoL were maintained after stratifying by lung function. In the absence of depressive symptoms, those patients with good lung function (ie, FEV(1), > 70% predicted) reported better physical HRQoL than those with poor lung function. Participants with both depressive symptoms and poor lung function reported significantly worse HRQoL on all domains than participants without depressive symptoms regardless of lung function status. CONCLUSIONS Depressive symptoms are prevalent among adults with CF and are associated with poorer HRQoL even after controlling for lung function. These results suggest that screening for and treating depression is important and may potentially improve HRQoL among patients with CF.