Abstract
BACKGROUND: Although international guidelines on pulmonary rehabilitation acknowledge that psychological factors contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD), the few empirical studies investigating this association have found inconsistent results. PURPOSE: The purpose of this study is to investigate whether negative affect and beliefs about exercise of patients with COPD would be related to baseline 6-min walk (6-MW) test results in a pulmonary rehabilitation setting, after correction for physical variables (sex, age, height, weight, and lung function). A second aim was to examine whether patients' beliefs are associated with treatment outcomes, as measured by an improvement in 6-MW distance. METHOD: A 12-week pulmonary rehabilitation program was completed by 166 patients. Beliefs (perceived necessity and concerns) about exercise and negative affect were assessed by a questionnaire. Clinical data were obtained from medical records. RESULTS: Baseline 6-MW distance was positively related to younger age, male gender, better pulmonary function, and having fewer concerns about exercise. After rehabilitation, patients had increased their walk distance by 12% (32 m), on average. Baseline physiological and psychological variables were unrelated to patients' response to treatment (increase in walk distance). However, subgroup analysis showed that for patients with mild to moderate airflow obstruction, concerns about exercise were negatively related to response to treatment. CONCLUSION: We conclude that patients' beliefs about the negative consequences of exercise are associated with baseline 6-MW test performance and response to treatment for patients with mild to moderate COPD. We recommend that patients' concerns about exercise are discussed and, if necessary, corrected during the intake phase.