Multivariate models of determinants of health-related quality of life in severe chronic obstructive pulmonary disease

Persons with severe chronic obstructive pulmonary disease (COPD) and similar levels of forced expiratory volume in 1 second (FEV(1)), exercise capacity, and dyspnea have a wide range of health-related quality of life (HRQL). We identified the independent determinants of HRQL in persons with COPD. Comprehensive assessments of physiological, psychosocial, and clinical variables from the National Ernphysema Treatment Trial were used. HRQL was assessed by the Medical Outcomes Study 36-Item Short Form Physical Component Summary (PCS) and Mental Component Summary (MCS) scores and the St. George's Respiratory Questionnaire total score (SGRQ-TS). In multivariate linear regression models, exercise capacity, dyspnea, age, single-breath diffusing capacity of the lung for carbon monoxide percent predicted, and self-report of being disabled were significant determinants of PCS score. Dyspnea, depression, antidepressant use, daytime sleepiness, and education were significant determinants of MCS score. Prior participation in pulmonary rehabilitation, Supplemental oxygen use, and oral corticosteroid use were significant determinants of SGRQ-TS. Although FEV(1), 6-minute walk test distance, and dyspnea significantly correlated with HRQL, their effects on HRQL were reduced when other variables were considered. Greater exercise capacity, prior participation in pulmonary rehabilitation, and use of supplemental oxygen were significantly associated with better HRQL. Self-perception of being disabled, depression, dyspnea, oral corticosteroid use, and daytime sleepiness were associated with worse HRQL. To optimize HRQL, clinicians should pay attention to a number of clinical and physiological factors.