Effect of psychological factors on exercise capacity (EC) and health-related quality of life (HRQL) in COPD undergoing pulmonary rehabilitation (PR)

Abstract

Background: Lung function and peripheral skeletal muscle changes following PR in COPD have been studied in detail, whilst psychological changes have not. We investigated the relationship between psychological factors, HRQL and EC in COPD patients undergoing PR. Method: Patients were assessed before and after an 8-week 16-session PR programme. Body mass index (BMI), fat free mass (FFM), forced expiratory volume in 1s (FEV1), self-efficacy (SE), state anxiety (SA), anxiety, depression and perceived exercise necessity and concerns were measured. HRQL was assessed with the chronic respiratory disease questionnaire (CRDQ) and EC with an incremental shuttle walk test (ISWT). Results: 42 patients enrolled (24males, 67.5(9.5)years, FEV1 1.11(0.57), BMI 28.5(7.5)kg.m2, FFM 63.6(6.9)%), with 12 remaining at follow-up. At baseline, ISWT(182(135)m) correlated with FEV1(r=0.36;p=0.020) and FFM%(r=0.42;p=0.010); CRDQ correlated with FEV1(r=0.37;p=0.020), concerns(r=-0.62;p Conclusion: As previously shown, changes in EC and HRQL over an 8-week PR programme has limited correlation with lung function. Indeed improvements were correlated with SA and SE, and a perceived need to exercise may be important. In the short term, psychological factors may play a greater role than physiological factors in improving HRQL and EC in severe COPD.