Comparative Measurement Properties of Constant Work-Rate Cycling and Endurance Shuttle Walking in Patients with COPD: Data from the TORRACTO Study

Rationale:

Little is known about comparative measurement properties of constant work-rate cycle ergometry (CWRCE) and the endurance shuttle walk test (ESWT). A secondary objective of the TORRACTO study (1237.15 [NCT01525615]) was to address this question.

Methods:

TORRACTO was a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial evaluating the effect of the combination of tiotropium (T) and olodaterol (O) on exercise endurance time (EET) in patients with COPD during CWRCE (75% peak work capacity achieved during incremental cycle ergometry) and ESWT (walking speed corresponding to 85% predicted peak VO2 achieved during an incremental shuttle walk test). Patients with COPD (GOLD 2 – 3) received T/O (2.5/5 or 5/5 µg) or placebo once daily (via Respimat inhaler) and performed CWRCE (all patients) and ESWT (subset of patients) at baseline and after treatment. This secondary analysis of the ESWT subset compared measurement properties of both tests, in the same individuals, in the context of a multicenter trial. The reproducibility of EET during CWRCE and ESWT was assessed by comparing EET at baseline and Week 6 in the placebo group. Responsiveness was assessed by comparing EET for T/O (pooled data from active treatment groups) during CWRCE and ESWT at 6 weeks versus baseline (paired t-test) and versus placebo (mixed model repeated measures analysis with baseline as covariate).

Results:

Overall, 162 patients performed both CWRCE and ESWT at baseline and Week 6: placebo, n = 49; T/O 2.5/5 µg, n = 54; T/O 5/5 µg, n = 59. In the placebo group, mean ± standard deviation (SD) EET for CWRCE was 502.1 ± 219.9 seconds at baseline and 437.8 ± 180.2 seconds at Week 6 (intraclass correlation coefficient [ICC]: 0.55), while mean ± SD EET for ESWT was 346.3 ± 186.5 seconds at baseline and 363.4 ± 231.0 seconds at Week 6 (ICC: 0.75). Both tests were responsive to bronchodilation as shown in the Table.

Week 6 vs. baseline	EET (seconds)		Ratio of EET at Week 6 vs. baseline
(T/0 group)	Baseline geometric mean ± SE	Week 6 geometric mean ± SE	Mean ± SE	95% CI	p value
CWRCE	410.24 ± 22.620	477.43 ± 25.868	1.164 ± 0.0531	1.063, 1.274	0.0012
ESWT	316.75 ± 17.137	382.47 ± 23.588	1.207 ± 0.0626	1.089, 1.338	0.0004
Week 6	EET (seconds)		Ratio of EET at Week 6, T/O vs. placebo
(T/0 vs. placebo)	Placebo geometric mean ± SE	T/O geometric mean ± SE	Mean ± SE	95% CI	p value
CWRCE	385.1 ± 23.5	484.7 ± 19.4	1.258 ± 0.092	1.090, 1.453	0.0019
ESWT	312.0 ± 22.4	377.0 ± 17.9	1.208 ± 0.104	1.020, 1.432	0.0291
Common baseline geometric mean ± SE for CWRCE: 420.3 ± 18.27 seconds; T/O (n = 114), placebo (n = 49). Common baseline geometric mean ± SE for ESWT: 311.2 ± 13.68 seconds; T/O (n = 115), placebo (n = 50). CI, confidence interval; SE, standard error.

Conclusions:

The test-retest reliability of EET was somewhat better for the ESWT; this may be explained, at least in part, by technical aspects of the tests as performed in the study (e.g. pre-determined upper limit for EET at baseline, specific work rate/walking speed selected). EET during both CWRCE and ESWT was responsive to T/O treatment.

Sponsored by Boehringer Ingelheim.

Previously presented at ATS 2017.