Predicting Peak Oxygen Uptake From the 6-Minute Walk Test in Patients With Pulmonary Hypertension

PURPOSE: To determine whether the 6-minute walk test (6MWT) is a predictor of peak oxygen uptake ((V) over dotO(2)) in patients with idiopathic pulmonary arterial hypertension (IPAH). METHODS: A total of 157 patients treated for IPAH completed a 6MWT in accordance with American Thoracic Society standards. Heart rate, pulse oximetry, and Borg rating of perceived exertion were determined at baseline and posttest. A cardiopulmonary exercise test (CPET) was performed on a cycle ergometer using a ramp protocol. Participants were stratified post hoc by age into 3 groups: children (n = 26), adolescents (n = 49), and adults (n = 82). Multiple linear regression analysis was performed to predict peak (V) over dotO(2) from the 6MWT. RESULTS: The regression equation generated for the children was the only model to strongly predict peak (V) over dotO(2) (r = 0.87; P < .001). Similar models for adolescent (r = 0.59; P < .001) and adult groups (r = 0.68; P < .001) did not achieve the same level of correlation. CONCLUSION: Six-Minute Walk Test was able to accurately predict peak (V) over dotO(2) in children (6-12 years) with IPAH; however, the model was weaker for predicting peak (V) over dotO(2) in older populations. These findings suggest that 6MWT may be as valid a test for predicting peak (V) over dotO(2) in children with IPAH as CPET measured peak (V) over dotO(2). In older IPAH populations, CPET is the only reliable method for the evaluation of peak (V) over dotO(2).