Reliability of ventilatory parameters during cycle ergometry in multicentre trials in COPD

We studied the distribution profiles and repeatability of key exercise performance parameters in the first large multicentre trials to include these measurements in chronic obstructive pulmonary disease (COPD). After a screening visit, 463 subjects with COPD (mean +/- SD forced expiratory volume in 1 s 43 +/- 13% predicted) completed two run-in visits before treatment randomisation. At the run-in visits, measurements were conducted at rest, at a standardised time near end-exercise (isotime) and at peak exercise during constant work rate (CWR) cycle tests at 75% of each individual's maximum work capacity. The intraclass correlation coefficient was used to evaluate the test-retest repeatability of measurements of endurance time (ET), inspiratory capacity (IC), ventilation and dyspnoea intensity (Borg scale) during exercise. IC, ventilation and dyspnoea ratings were normally distributed; ET showed rightward skew (median < mean, skewness of 10.9 (much greater than zero)) with 16% of the sample exceeding 1 SD of the mean. ET was highly repeatable across run-in visits: 7.9 +/- 4.8 and 8.4 +/- 5.1 min (R=0.84). IC values at rest, isotime and peak exercise were all highly repeatable (R >= 0.87). Ventilation was repeatable over the same time-points (R >= 0.92), as was dyspnoea intensity at isotime (R=0.79) and at peak exercise (R=0.81). In conclusion, key perceptual and ventilatory parameters can be reliably measured during CWR cycle exercise in multicentre clinical trials in moderate to very severe COPD.