Effects of depressive symptoms on health-related quality of life in asthma patients.

Abstract

To assess the effects of depressive symptoms on asthma patients' reports of functional status and health-related quality of life. Cross-sectional study. Primary care internal medicine practice at a tertiary care center in New York City. We studied 230 outpatients between the ages of 18 and 62 years with moderate asthma. Patients were interviewed in person in English or Spanish with two health-related quality-of-life measures, the disease-specific Asthma Quality of Life Questionnaire (AQLQ) (possible score range, 1 to 7; higher scores reflect better function) and the generic Medical Outcomes Study SF-36 (general population mean is 50 for both the Physical Component Summary [PCS] score and Mental Component Summary [MCS] score). Patients also completed a screen for depressive symptoms, the Geriatric Depression Scale (GDS), and a global question regarding current disease activity. Stepwise multivariate analyses were conducted with the AQLQ and SF-36 scores as the dependent variables and depressive symptoms, comorbidity, asthma, and demographic characteristics as independent variables. The mean age of patients was 41 +/- SD 11 years and 83% were women. The mean GDS score was 11 +/- SD 8 (possible range, 0 to 30; higher scores reflect more depressive symptoms), and a large percentage of patients, 45%, scored above the threshold considered positive for depression screening. Compared with patients with a negative screen for depressive symptoms, patients with a positive screen had worse composite AQLQ scores (3.9 +/- SD 1.3 vs 2.8 +/- SD 0.8, P <.0001) and worse PCS scores (40 +/- SD 11 vs 34 +/- SD 8, P <.0001) and worse MCS scores (48 +/- SD 11 vs 32 +/- SD 10, P <.0001) scores. In stepwise analyses, current asthma activity and GDS scores had the greatest effects on patient-reported health-related quality of life, accounting for 36% and 11% of the variance, respectively, for the composite AQLQ, and 11% and 38% of the variance, respectively, for the MCS in multivariate analyses. Nearly half of asthma patients in this study had a positive screen for depressive symptoms. Asthma patients with more depressive symptoms reported worse health-related quality of life than asthma patients with similar disease activity but fewer depressive symptoms. Given the new emphasis on functional status and health-related quality of life measured by disease-specific and general health scales, we conclude that psychological status indicators should also be considered when patient-derived measures are used to assess outcomes in asthma.