Endurance Time Is the Most Responsive Exercise Measurement in Idiopathic Pulmonary Fibrosis

BACKGROUND: Although pulmonary rehabilitation (PR) has been reported to improve exercise capacity in patients with idiopathic pulmonary fibrosis, it is unknown which exercise measurement is the most responsive for evaluation of PR efficacy. The purpose of this study was to compare the responsiveness of 5 exercise measurements by evaluating the efficacy of PR in subjects with idiopathic pulmonary fibrosis. METHODS: We conducted a prospective observational study in which 53 subjects with idiopathic pulmonary fibrosis were enrolled. The PR group underwent a 10-week out-patient PR program. The control group was observed without any additional intervention, including PR. Five exercise measurements (endurance time [ET], peak work rate, peak oxygen consumption [(V) over dot(O2)] 6-min walk distance, and incremental shuttle walk distance) were evaluated at baseline and after 10 weeks. The effect size was used for the assessment of responsiveness. RESULTS: In each group, 24 subjects completed the 5 measurements at baseline and after 10 weeks. The changes in ET (PR: 181.6%; control: -8.2%), peak (V) over dot(O2) (PR: 7.6%; control: -5.4%), peak work rate (PR: 15.1%; control: -5.1%), 6-min walk distance (PR: 6.0%; control: -3.8%), and incremental shuttle walk distance (PR: 9.1%; control: -5.1%) were significantly different between the groups after 10 weeks (P < .05). In the PR group, ET showed the most striking improvement among the 5 measurements (P < .05), and its effect size was as large as 2.96, whereas those of the others were all < 0.5. CONCLUSIONS: ET is the most responsive exercise measurement for evaluating PR efficacy in patients with idiopathic pulmonary fibrosis.