Background: There is currently no consensus regarding which factors influence the quality of life of patients suffering from chronic obstructive pulmonary disease (COPD). However, identifying such factors could orient approaches to improving the quality of the lives of these patients. Objective: To evaluate factors that can interfere with quality of life in COPD patients selected for pulmonary rehabilitation. Methods: Twenty-one patients with moderate to severe COPD were evaluated. Maximal inspiratory pressure (MIP), 6-minute walk test (6MWT), body mass index (BMI), pulmonary function, blood gases, grip strength (measured with a dynamometer), quadriceps strength and St. George's Respiratory Questionnaire (SGRQ) scores were assessed. Results: Statistically significant negative correlations with quality of life were found for the following factors: "impact" scores of: forced expiratory volume in one second (FEV1) (r = -0.68; p = 0.004), FEV1 to forced vital capacity ratio (FEV1/FVC) (r = -0.61; p = 0.014), peak expiratory flow (PEF) (r = -0.53 (p = 0.015), 6MWT (r = -0.63; p = 0.001) and BMI (r = -0.64; p = 0.002); "activity" scores for: MIP (r = -0.57; p = 0.007), baseline arterial oxygen saturation by pulse oximetry (SpO2) (r = -0.52; p = 0.018) and 6MWT (r = -0.58; p = 0.007); "symptom" score for: BMI (r = -0.60; p = 0.005); and "total" scores for: FEV1 (r = -0.64; p = 0.01), PEF (r = -0.47; p = 0.033) and BMI (r = -0.57; p = 0.009). Multiple linear regression revealed the primary factors influencing quality of life to be: BMI, which presented a significant influence on "symptom", "impact" and "total" scores (p = 0.002, p = 0.009 and p = 0.024, respectively); and 6MWT, which had a significant influence on "activity" and "impact" scores (p = 0.048 and p = 0.010, respectively). Conclusions: The BMI and 6MWT were shown to have an influence on quality of life in the COPD patients studied. Therefore, therapeutic approaches to improving the quality of life of COPD patients should take these indices into consideration.

Keywords: Lung diseases, obstructive/rehabilitation. Quality of life