A prediction model for estimating pulmonary oxygen uptake during the 6-minute walk test in organ transplant recipients

We developed a multivariate prediction equation for estimating the highest obtainable pulmonary oxygen uptake (VO2p) during the 6-minute walk test (6-MWT) in 54 organ transplant recipients: heart/heart-double-lung (n = 14), kidney/kidney-pancreas (n = 16), liver (n = 14), double lung (n = 8), bone marrow (n = 2). They were of age, 48 +/- 12 years. Participants performed a 6-MWT during which expired gases were collected and analyzed with a portable metabolic system interfaced with a wireless heart rate monitor. The following variables significantly contributed to the model for predicting the highest obtainable 6-MWT VO2p: 6-MWT distance (m), age (years), gender (male = 0, female = 1), resting heart rate, peak heart rate, weight (kg), and transplant type (kidney/kidney-pancreas = 1, other = 0), where: VO2p = 1.253 + 0.022 (6-MWT distance) + 0.112 (age) -3.192 (gender) -0.104 (resting heart rate) + 0.127 (peak 6-MWT heart rate) - 0.084 (weight) + 2.116 (transplant type). The explanatory variables in our final model accounted for 78% of the variance in 6-MWT VO2p. In conclusion, the addition of an easily estimated 6-MWT VO2p will provide added clinical information of functional capacity following an exercise rehabilitation intervention or during routine follow-up for organ transplant recipients.