COPD Comorbidities And Their Impact On Quality Of Life

Abstract

Background: In COPD, respiratory symptoms, exacerbations and lung function affect quality of life (QOL), but how comorbidities impact QOL is undefined Methods: We analyzed COPDGene subjects with COPD. Based upon patient-report of physician-diagnosed comorbidities, we calculated two composite comorbidity measures: the modified Charlson index, and the Fan modification of the Functional Comorbidity index (mFCI) (a self-reported comorbidity score comprising arthritis, osteoporosis, stroke, angina, diabetes, congestive heart failure, heart attack, stomach ulcers, cancer, kidney disease and pneumonia). We evaluated the independent effect of these indices on QOL using multivariate models adjusted for demographics and pulmonary function. Gastroesophageal reflux disease (GERD), not part of those indices, was included individually. Data are presented as mean [SD] unless noted. Results: From the full COPDGene cohort of 10,276 individuals, we analyzed 4,475 subjects (1,974 female, 2,501 male) with COPD, with age 65.1 [8.6] years, Charlson index 1.56 [1.0], and mFCI 1.5 [1.34]. SGRQ total score was 36.9 [22.9], with the following subscores: activity 51.7 [29.3], impact 26.7 [21.9], symptom 42.5 [25.8]. In the SF-36, the mental component score (MCS) was 48.7 [12.6]; the physical component score (PCS) was 40.5 [11.0]. Adjusted multivariate models demonstrated a significant relationship between comorbidities (by mFCI but not by Charlson index) and increase in SGRQ {total score (2.53, p<0.0001)}, and its components {activity (2.59, p<0.0001), impact (2.41, p<0.0001), and symptom (2.80, p<0.0001)}. mFCI also correlated with decrease in SF-36 PCS (-1.18, p<0.0001) and SF-36 MCS (-1.25, p<0.0001). The highest contribution of a single comorbidity to QOL was made by GERD, which was significantly associated with total SGRQ (4.37, p<0.0001); its components {activity (4.58, p<0.0001), impact (3.80, p<0.0001), and symptom (5.85, p<0.0001)}; and with SF-36 PCS (-2.11, p<0.0001), but not SF-36 MCS (-0.94, p=0.11). Although women reported some comorbidities more frequently than men {GERD (34% vs. 26%, p<0.001), osteoporosis (23% vs. 5%, p<0.001), osteoarthritis (26% vs. 17%, p<0.0001)}, no interaction between gender and comorbidities was found. The contribution of comorbidity, measured by mFCI, to explained variance of SGRQ total score was 6.7%, and for the activity scale was 7.0%. Comorbidities explained 7.3% of the variance of the SF-36 PCS score, but only 1.2% of SF-36 MCS. Conclusions: Among COPDGene participants with COPD, comorbidities are frequent and significantly affect QOL. The separate contribution of comorbidities to QOL was greater for SGRQ total and activity scores and for SF-36 PCS. GERD was the individual comorbidity with the greatest influence on QOL.