Depression Is Significantly Associated with the Health Status in Patients with Idiopathic Pulmonary Fibrosis

OBJECTIVE: Depression is reported to be relatively common in idiopathic pulmonary fibrosis (IPF) patients. Thus far, however, whether or not depression independently determines the health-related quality of life (HRQOL) has not been evaluated exclusively in IPF patients. We designed this study to identify independent determinants of the St. George’s Respiratory Questionnaire (SGRQ) score among various factors, including a depression scale, in IPF patients. METHODS: We retrospectively analyzed consecutive subjects with IPF who completed a systematic evaluation including pulmonary function tests, PaO(2) at rest, 6-minute walk test (6MWT), SGRQ, Baseline Dyspnea Index (BDI), and Hospital Anxiety and Depression Scale (HADS). All eligible patients in the present study had newly diagnosed IPF and had not received any prior treatments, such as antidepressants, pirfenidone, corticosteroids, immunosuppressants, or long-term oxygen therapy. RESULTS: The 121 patients with IPF included 99 men. On the SGRQ, mild to moderate disturbance was observed in the total and each component score. According to the HADS, 27 patients (22.3%) had borderline or definite depression. In a univariate regression analysis, the forced vital capacity (FVC), diffusion capacity of carbon monoxide (DLco), PaO(2) at rest, BDI, HADS for Anxiety (HADS-A) and Depression (HADS-D), 6-minute walk distance (6MWD), and lowest SpO(2) during the 6MWT were significantly correlated with the SGRQ total score. In a stepwise multiple regression model, BDI, 6MWD, and HADS-D were selected as independent determinants of the total SGRQ score. The total variance in this model was 59% (p＜0.001). CONCLUSION: We concluded that depression was a significant determinant of the HRQOL or health status in patients with IPF.