Criterion Validity and Responsiveness of the Steep Ramp Test to Evaluate Aerobic Capacity in Survivors of Cancer Participating in a Supervised Exercise Rehabilitation Program
Anouk T.R. Weemaes, Milou Beelen, Bart C. Bongers, Matty P. Weijenberg, Antoine F. Lenssen
Abstract
ObjectiveTo evaluate the criterion validity and responsiveness of the steep ramp test (SRT) compared with the cardiopulmonary exercise test (CPET) in evaluating aerobic capacity in survivors of cancer participating in a rehabilitation program.DesignA prospective cohort study in which survivors of cancer performed an SRT and CPET before (T=0) and after (T=1) a 10-week exercise rehabilitation program. Peak work rate achieved during the SRT (SRT-WRpeak) was compared with peak oxygen consumption measured during the CPET (CPET-Vo2peak), which is the criterion standard for aerobic capacity. Correlation coefficients were calculated between SRT-WRpeak and CPET-Vo2peak at T=0 to examine criterion validity and between changes in SRT-WRpeak and CPET-Vo2peak from T=0 to T=1 to determine responsiveness. Receiver operating characteristic analysis was performed to examine the ability of the SRT to detect a true improvement (6%) in CPET-Vo2peak.SettingUniversity medical center.ParticipantsSurvivors of cancer (N=106).InterventionsExercise rehabilitation.Main Outcome MeasuresCorrelation coefficients between CPET-Vo2peak and SRT-WRpeak and between changes in CPET-Vo2peak and SRT-WRpeak.ResultsAn r of 0.86 (N=106) was found for the relation between SRT-WRpeak and CPET-Vo2peak at T=0. An r of 0.51 was observed for the relation between changes in SRT-WRpeak and CPET-Vo2peak (n=59). Receiver operating characteristic analysis showed an area under the curve of 0.74 for the SRT to detect a true improvement in CPET-Vo2peak, with an optimal cutoff value of +0.26 W/kg (sensitivity 70.7%, specificity 66.7%).ConclusionsBecause SRT-WRpeak and CPET-Vo2peak were strongly correlated, the SRT seems a valid tool to estimate aerobic capacity in survivors of cancer. The responsiveness to measure changes in aerobic capacity appears moderate. Nevertheless, the SRT seems able to detect improvement in aerobic capacity, with a cutoff value of 0.26 W/kg.