Exercise capacity impairment in COPD patients with comorbidities

Background: Comorbidities are common in COPD and have been associated with reduced health status, increased health care utilization, all-cause hospitalization, and mortality. There is a scarcity of data on the relationship between comorbidities and functional capacity. Objective: to evaluate the impact of comorbidities on functional capacity of COPD patients. Methods: a cross-sectional study was conducted at two teaching hospitals in Fortaleza, Brazil. The functional capacity was assessed by spirometry and the 6-min walking test (6MWT). The health status was assessed by the St. George's respiratory questionnaire (SGRQ) and the COPD assessment test (CAT). The sample was stratified as having "none", "one" and "two or three'' comorbidities groups. One-way ANOVA was used to compare means of the three groups and a multiple linear regression was run to predict the impact of comorbidities on 6MWT. Results: Comorbidities (hypertension, coronary disease and diabetes) were found in 54% of the studied patients. The mean age of the 79 patients was 67 +/- 8 years and 55% were male. CAT scores increased from "no comorbidity" (17.9 +/- 7.7) to "one comorbidity" (22.8 +/- 6.8) and "two or three comorbidities" groups (24.2 +/- 10.2). A post hoc test showed a significant difference in the "no comorbidity" compared to the "two or three comorbidities" groups (p = 0.01). The distance walked by the patients decreased from "no comorbidity" (386.1 +/- 83.2 m) to "one comorbidity" (350 +/- 98 m) and "two or three comorbidities" groups (312.6 +/- 91 m). A post hoc test showed significant difference in the "no comorbidity" compared to "two or three comorbidities" groups (p = 0.007). Numbers of comorbidities were independently associated with the 6 MWT adjusting for age, severity of COPD and CAT scores. Conclusion: in the studied sample, the presence of comorbidities contributed to impair exercise capacity in patients with COPD. (C) 2014 Sociedade Portuguesa de Pneumologia. Published by Elsevier Espana, S.L.U. All rights reserved.