The purpose of this study was to evaluate the oxygen uptake efficiency slope (OUES) as a predictor of peak oxygen consumption (Vo₂) in aged patients with coronary artery disease (CAD) and to compare its predictive value to that of ventilatory anaerobic threshold (VAT).

A total of 160 aged (>60 years) patients with stable CAD performed a maximal cardiopulmonary exercise test. The equations were computed by using data of 85 randomly selected patients and were validated in the remaining 75 patients. Bland-Altman (BA) analysis was used to assess the agreement between measured and predicted peak Vo₂.

In the first 85 patients, peak Vo₂ correlated best with VAT and OUES per kilogram (P < .001). The linear regression to predict peak Vo₂ for OUES per kilogram was peak Vo₂ = 4.591 + 0.64 × OUES/kg (SEE = 2.61 mL kg⁻¹ min⁻¹). The BA 95% limits of agreement were −29% and +30% of the predicted value. For VAT, the linear regression to predict peak Vo₂ was peak Vo₂ = 2.995 + 1.251 × VAT (SEE = 2.26 mL kg⁻¹ min⁻¹). The BA 95% limits of agreement were −23% and +33% of the predicted value. Cross-tabulation analysis in 3 subgroups with different exercise capacities showed significant relationship between predicted and measured peak Vo₂ (all P < .001). OUES per kilogram showed the best measure of agreement with measured peak Vo₂, resulting in high sensitivity and specificity scores.

OUES is not able to acceptably predict peak Vo₂ in aged patients with CAD but is at least as performant as VAT in categorizing patients into subgroups with different exercise capacities. Therefore, the objectively measurable OUES is the preferred submaximal predictor of functional capacity in the assessment of aged patients with CAD.