Background: COPD is often associated with other chronic diseases. These patients are often admitted to hospital-based rehabilitation programs. Objectives. To determine the prevalence of chronic comorbidities in COPD patients undergoing pulmonary rehabilitation (PR) and to assess their influence on the outcomes.
Design: Observational retrospective cohort study. Setting. A single rehabilitation centre. Patients. 2,962 inpatients and outpatients with COPD (73% male, age 71 [SD 8] yr, FEV1 49.3 [SD14.8] % of predicted), graded 0, 1 or ≥2 according to the Comorbidity categories and included in a PR program. Measurements. We analyzed the number of self-reported comorbidities and recorded the Charlson index. We then calculated the percentage of patients with a predefined positive response to pulmonary rehabilitation (=minimally clinical important difference-MCID) as measured by improvement in exercise tolerance (6MWD), dyspnea (MRC), and/or health-related quality of life (SGRQ).
Results: 51% of the patients reported at least one chronic comorbidity added to COPD. Metabolic (systemic hypertension, diabetes, and/or dyslipidemia) and heart diseases (chronic heart failure and/or coronary heart disease) were the most frequently reported comorbid combinations (61 and 24%, respectively) among the overall diseases associated with COPD. The prevalence of patients with MCID was different across the Comorbidity categories and outcomes. In a multiple categorical logistic regression model, the Charlson index (OR 0.72, 96%CI 0.54 to 0.98 and 0.51, 96%CI 0.38 to 0.68, versus 6MWD and SGRQ respectively), metabolic diseases (OR 0.57, 96%CI 0.49-0.67 versus 6MWD) and heart diseases (OR 0.67, 96%CI 0.55 to 0.83 versus SGRQ) reduced the probability to improve outcomes of rehabilitation.
Conclusions: Most patients with COPD undergoing PR have one or more comorbidities. Despite the presence of comorbidities does not preclude the access to rehabilitation, the improvement in exercise tolerance and quality of life after rehabilitation may be reduced depending on comorbidity.