Prediction of peak oxygen consumption in patients with intermittent claudication

Determination of peak oxygen consumption (VO₂peak) is considered important for assessing a patient's functional capacity and for exercise prescription. However, the equipment necessary to obtain accurate determination of Vo₂peak is not always available in clinical settings. The present study sought to develop an equation to estimate Vo₂peak in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and to determine independent predictors of Vo₂peak in this population. One hundred and fifty-seven patients with intermittent claudication were assigned to either a validation group (n = 105) or a cross- validation group (n = 52). Medical history, height, weight, body mass index (BMI), age, gender, smoking status, resting and postexercise ankle/brachial systolic pressure index (ABI), and time to maximal claudication pain and maximal heart rate from an incremental graded exercise test (GXT) were used as potential independent predictors of Vo₂peak. Time to onset of maximal claudication pain, maximal heart rate, and BMI were all independently associated with Vo₂peak. These variables were used to estimate Vo₂peak by the following equation: Vo₂peak (mL/kg/min) = (0.00872 x maximal claudication pain time [sec]) + (0.02839 x maximal heart rate [b/min]) - (0.12034 x BMI) + 10.11411 r = 0.71, r² = 0.50, standard error of estimate = 2.02 mL/kg/min, p < 0.0001. There was no significant difference between the estimated and actual VO₂peak in the cross-validation group, and the coefficient of variation between estimated and actual Vo₂peak in this group was 18.3%. There was no significant difference between the correlation coefficient for the relationship between estimated and actual Vo₂peak in the cross-validation group (r = 0.61) and the multiple correlation coefficient from the validation group (r = 0.71). Results of this study suggest that a multiple regression equation can be used to estimate Vo₂peak in patients with intermittent claudication by measuring time to maximal claudication pain and maximal heart rate from a GXT and by measuring BMI.