Test-retest reliability of cardiopulmonary exercise test-derived metrics in individuals with COPD versus healthy controls

Abstract

Background

Cardiopulmonary exercise testing (CPET) is usually considered the gold standard for assessing maximal oxygen consumption (V̇O_2max), a health and performance marker in patients with chronic obstructive pulmonary disease (COPD). Despite the widespread application of CPET, the absolute and relative test-retest reliability of CPET-derived metrics remains unexamined.

Objective

To examine and compare test-retest reliability of CPET derived metrics in individuals with COPD and healthy matched controls.

Methods

12 individuals with COPD and 12 healthy age- and sex-matched controls were included in this case-control study. Each participant completed two CPET on a bicycle ergometer on two different days. Absolute reliability was reported as smallest real difference (SRD) and relative reliability as coefficient of variance (CV) and intraclass correlation coefficients (ICC).

Main Results

SRD for peak oxygen uptake was 451.6 (267.4;1006.4) mL/min and CV was 7.8 (4.7;11.0)% in patients with COPD, whereas SRD was 244.2 (151.4;491.5) mL/min and CV was 3.0 (1.8;4.2)% in healthy controls but with no significant between group difference for SRD. CV values for all CPET derived metrics were found to be below 10%. Apart from peak workload achieved and peak minute ventilation, SRD and CV were significantly higher in COPD than in controls for all other CPET-derived metrics.

Conclusion

This study provides test-retest reliability estimates of the most widely used CPET derived metrics in individuals with COPD and healthy matched controls. Test-retest reliability for most metrics derived from CPET were found to be lower in individuals with COPD when compared to healthy controls.