Objective: To identify factors associated with the health-related quality of life (HRQL) perceived by patients with stable chronic obstructive pulmonary disease (COPD).
Design: Prospective cohort study.
Subjects: Patients with stable COPD (n = 204, alpha = 0.05, d = 6.9%). MEASURES AND INTERVENTIONS: For every patient we recorded sociodemographic and treatment data,severity of dyspnea, and the results of gasometry and lung function and stress testing, as well as responses to the Chronic Respiratory Disease Questionnaire (CRDQ). After studying the associations between variables we carried out factor analysis of those that were significantly related to HRQL.
Results: Men made up 91.7% of the cohort. The mean age (standard deviation)was 71 (9), FEV1% was 45 (16) and FEV1/FVCwas 48 (10). HRQL was statically related to age, weight, body mass index (BMI), economic status, educational status, chronic treatment with oral corticosteroids, ODCA, PaO2, oxygen saturation, alveolar-arterial oxygen gradient, absolute FEV1, FEV1%, post-bronchodilatation FEV1, absolute FVC, FVC%, distance walked in six minutes, oxygen saturation before the walking test and lowest oxygen saturation during the test,difference in dyspnea before and after the test measured on a visual analog scale. Factor analysis reduced the main variables to six, which explained 74.6% of the variance, as follows: Factor1 PaO2, oxygen saturation and alveolar-arterial oxygen gradient (33.7%); Factor 2 absolute FEV1,FEV1%, FEV1 after bronchodilatation, absolute FVC and FVC% (11.9%); Factor 3 eight and BMI (8.8%); Factor 4 age, severity of dyspnea and walking test distance (8.4%);Factor 5: corticosteroid dependence and domiciliary oxygen therapy(6.3%); and Factor 6: economic and educational status (5.5%).
Conclusion: HRQL in stable COPD patients is partially related to severity of respiratory insufficiency, airflow obstruction, nutritional status, exercise capacity, severity of disease, and socioeconomic status.