Abstract
Rationale: Cardiopulmonary exercise test (CPET) is used to monitor disease progression and prognosis. When following up subjects, stability of the parameters from CPET is essential.
Methods: 131 subjects (43 nonsmokers, 63±6 years; 49 (ex-) smokers, 62±6 years; and 39 subjects with mild COPD, 63±6 years, FEV1 90±15%pred) were included. CPET was performed at baseline and 3 years of follow up. Absolute and relative to baseline changes and the coefficient of variance were calculated for maximal oxygen uptake (VO2peak), ratio between oxygen consumption and work rate (VO2/WR), oxygen uptake efficiency (OUES) and ventilatory efficiency (VE/VCO2) slopes.
Results: Variables related to peak performance and OUES deteriorated over a period of three years. Other outcomes did not change.
Δ | Δ % baseline | |
VO2peak (ml/kg/min) | −3.45 (−10.03, 3.13) *p<0.0001 | −10.8 (−31.2, 8.8) * p<0.0001 |
VO2/WR (ml/min/w) | 0.16 (−2.84, 3.14) p>0.05 | 4.18 (−21.0, 33.2) p>0.05 |
OUES slope | −0.15 (−0.77, 0.42) *p<0.01 | −3,9 (−25.8, 19.8) p=0.0503 |
VE/VCO2 slope | −0.39 (−4.22, 3.00) p>0.05 | −0,7 (−13.3, 12.3) p>0.05 |
Data as means (p10, p90). Δ= absolute change; Δ% baseline= relative change; ml= milliliters; kg= kilograms; min= minute; w= watts.Δ
Conclusion: VE/VCO2 was the most stable of parameters in a 3 years follow up. An increase of more than 3 units would indicate an abnormal gas exchange deterioration.
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