Impact of comorbidities on COPD-specific health-related quality of life.

BACKGROUND: Comorbidities are frequent in subjects with COPD, but their contribution to health-related quality of life (HRQoL) impairment is not clearly established.
METHODS: Cross-sectional analysis of data from the French COPD cohort Initiatives BPCO. Data were recorded in stable state and included spirometry, dyspnea (modified Medical Research Council - mMRC-scale), mood disorders (hospital anxiety-depression scale) and physician-diagnosed comorbidities including diabetes, hypertension, coronary artery disease, chronic heart failure, venous thromboembolism. HRQoL was assessed using the disease-specific St. George's Respiratory Questionnaire (SGRQ). Stepwise forward and backward multiple regression analyses were performed to examine the contribution of comorbidities to SGRQ scores.
RESULTS: Data are median [IQR]. 326 COPD subjects were analyzed: male 77%, age 65.0 [57.0; 72.0] years, FEV(1) 48.9 [34.7; 65.9]% predicted. SGRQ total score was 44.2 [30.0; 61.2]. In univariate analysis, positive correlations were found between SGRQ total scores and dyspnea and exacerbations/patient/year, whereas negative correlations were found with FEV(1). SGRQ total scores were increased in women (P = 0.06), and in subjects with low BMI, anxiety or depression (each analysis, P < 0.001), but not in subjects with cardiovascular comorbidities or diabetes. In multivariate analyses, major independent determinants of SGRQ total score included dyspnea, exacerbations/patient/year and depression. Low BMI, coronary artery disease and FEV(1) were also independently associated with SGRQ total score, but their contribution was only modest.
CONCLUSIONS: These data suggest that in the presence of dyspnea and exacerbation, depression is the most important contributor to HRQoL impairment measured by SGRQ in COPD subjects, whereas other comorbidities and FEV(1) have only limited impact.