Depression is a common and chronic comorbidity in patients with interstitial lung disease

Little is known about depression in interstitial lung disease (ILD). The aim of this study was to determine the prevalence of depression, characterize the association of depression with clinical variables and describe the natural history of depression in patients with ILD.

In this prospective cohort study, clinical variables were recorded at baseline and 6 months. Depression was measured with the Centre for Epidemiologic Studies Depression scale. Depression prevalence was determined using the established threshold of >15 points. Multivariate linear regression was used to determine the baseline features that independently correlated with baseline depression score and that predicted depression severity at follow-up.

Fifty-two subjects were enrolled, and 45 returned for follow-up (three deaths, one lung transplant). Prevalence of depression was 21% at baseline. Independent predictors of depressive symptoms at baseline included dyspnoea severity, pain severity, sleep quality and forced vital capacity (R(2) 0.67). The odds of clinically meaningful depression at follow-up were 34-fold higher for subjects who had clinically meaningful depression at baseline compared with those who were not (95% confidence interval 3.5-422, P < 0.0005). Baseline depression score was the strongest predictor of depression score at follow-up (r 0.59, P < 0.00005).

Depressive symptoms in ILD are common, persistent, and strongly and independently correlated with dyspnoea, pain, sleep quality and forced vital capacity. Clinically meaningful depression at baseline is the most important predictor of depressive symptoms at follow-up. Patients with ILD should routinely be screened for depression.