Table 2 Characteristics of variability of oxygen uptake (V̇O2) measurements during 129 biological quality control tests, using three different quality control methods
From: Biological quality control for cardiopulmonary exercise testing in multicenter clinical trials
Variable | Work rate (W) | Number (% of all tests) | Mean ± SD (% predicted) | Median (% predicted) | Coefficient of variation (%) | Normality (Shapiro–Wilk) |
|---|---|---|---|---|---|---|
V̇O2 at 20 W | ||||||
All tests | 20 | 129 (100) | 92.1 ± 12.2 | 93.5 | 14.3 | Passed |
Criteriona | 20 | 43 (33) | 96.1 ± 5.4 | 94.8 | 5.6 | P < 0.001 |
Readerb | 20 | 98 (76) | 91.9 ± 11.5d | 93.1 | 12.5 | Passed |
Composite z-scorec | 20 | 62 (48) | 95.8 ± 5.9 | 95.0 | 6.2 | Passed |
V̇O2 at 70 W | ||||||
All tests | 70 | 129 (100) | 97.5 ± 11.0 | 97.7 | 11.3 | Passed |
Criteriona | 70 | 43 (33) | 98.4 ± 4.1 | 98.1 | 4.2 | Passed |
Readerb | 70 | 98 (76) | 97.6 ± 9.4 | 97.1 | 9.6 | Passed |
Composite z-scorec | 70 | 62 (48) | 99.0 ± 4.6 | 98.4 | 4.7 | Passed |
∆V̇O2/∆WR | ||||||
All tests | ∆50 | 129 (100) | 105.7 ± 13.6 | 105.8 | 12.9 | P = 0.006 |
Criteriona | ∆50 | 43 (33) | 102.0 ± 5.4 | 102.5 | 5.3 | Passed |
Readerb | ∆50 | 98 (76) | 106.3 ± 11.4 | 105.1 | 10.7 | P < 0.001 |
Composite z-scorec | ∆50 | 62 (48) | 103.9 ± 6.2 | 104.3 | 6.0 | Passed |