Symptoms of depression impact the course of lung function in adolescents and adults with cystic fibrosis

Background: Epidemiological studies report high rates of depression among patients with cystic fibrosis (CF). Assuming a causal relationship between depression and the progression of CF, our hypothesis is that elevated symptoms of depression would be a predictor of worse lung function after two years. Methods: In the context of the TIDES study, 473 German patients with CF (age 12-53 years, FEV1% predicted M = 66.2, range 13-137) completed the Hospital Anxiety and Depression Scale (HADS). Lung function (FEV1% predicted) was assessed at baseline and followed up two years later. Repeated measures analysis was performed involving the level of FEV1% and the level of depressive symptoms at baseline as independent factors and FEV1% at the 2-year follow-up as the dependent variable. Results: Interaction between lung function and depression at baseline significantly affected the change in lung function at the 2-years observation interval. The largest decline in FEV1% occurred in depressed patients with good lung function at baseline. In contrast, patients without any clinically relevant depressive symptoms and with poor lung function at baseline showed a slight increase two years later. Conclusion: The findings emphasise the need to screen patients with CF for symptoms of depression and to treat co-morbid depression.