Comorbidities in Patients With Chronic Obstructive Pulmonary Disease and Pulmonary Rehabilitation Outcomes

Purpose: The objective of this study was to evaluate the impact of comorbidities as potential predictors of the response to pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD). Methods: The study included 165 patients with COPD with exercise limitations. Comorbidity was classified as cardiac, metabolic, orthopedic, behavioral health problems, or other diseases. Number of comorbidities was grouped as 0, 1, or >= 2. Outcomes were defined as improvement in exercise capacity (maximal exercise capacity, 6-minute walk test, and constant workload cycle exercise duration) and quality of life (Chronic Respiratory Questionnaire). We assessed the effect of comorbidities on improvement in outcomes and the impact of the number of comorbidities on the percentage of patients reaching the minimal clinically important difference for each outcome. Results: Most patients (n = 160; 96%) were elderly males (mean age 70 years) with COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages II to IV. Sixty-four percent of patients had at least 1 comorbidity. The >= 2 comorbidity group (n = 29) had a higher modified Charlson index and more patients required continuous supplemental oxygen. Absolute differences in dyspnea scores in patients with cardiac disease and orthopedic problems compared with those without these comorbidities were 2.6 +/- 0.87; 95% CI 0.89 to 4.32; p = .003, and -3.25 +/- 1.23; 95% CI -5.69 to -0.82; p = .009, respectively. Comorbidities had no significant effect on other exercise outcomes or quality of life. Conclusion: Patients with cardiac disease experienced greater improvement in the dyspnea score compared with patients with no cardiac disease, whereas patients with orthopedic problems had a smaller but also clinically significant improvement in dyspnea after pulmonary rehabilitation.