Disability in COPD and its relationship to clinical and patient-reported outcomes

Abstract

Objective: To assess the presence of disability in chronic obstructive pulmonary disease (COPD) patients and its relationships with disease severity, comorbidities, and patient-reported outcomes.

Research design and method: COPD outpatients completed validated questionnaires designed to investigate illness perception, well-being, quality of life, and stress, while physicians collected data concerning disability, dyspnea, and comorbidities (Charlson Index).

Results: Of 164 patients, 37.3% exhibited a degree of disability and 67.7 % of them reported the loss of at least one relevant function in daily life (mean 2.34 ± 2.41). Although disability was associated with disease severity (χ(2) = 8.292; p < 0.016), disability was present to some degree in all disease stages and in 44.9% of patients with moderate COPD. Barthel Index scores were related to MRC scores (r = 0.529; p < 0.001), GOLD stage (r = 0.223; p < 0.006), and Charlson Index (r = 0.163; p < 0.032). Disabled patients had a lower mean FEV(1) value (50.96 ± 20.99 vs. 65.00 ± 23.63; p < 0.001) than self-sufficient patients (p < 0.001). The stepwise regression analysis showed that the MRC score was the most relevant factor in inducing COPD patient disability (F = 56.5; p = 0.001). Compared to self-sufficient patients, disabled patients reported lower levels of well-being and health status, increased levels of distress, and a different illness perception.

Conclusions: Disability can be identified in each disease stage, with dyspnea serving as the most relevant inducing factor. Since disability substantially impacts patient perception of and experience with COPD, its presence must be taken into account during disease management. The cross-sectional nature of the study and the characteristics of the sample size represent a limitation in the possibility to generalize the results.