Test-Retest Reliability and Minimal Detectable Change of the SmartWheel Clinical Protocol

Lui J, MacGillivray MK, Sawatzky BJ. Test-retest reliability and minimal detectable change of the Smart Wheel clinical protocol. Arch Phys Med Rehabil 2012;93:2367-72. Objectives: (1) To quantify the intra- and intersession reliability and minimal detectable change (MDC) of the Smart Wheel clinical protocol (SCP) and (2) to compare the reliability of the SCP between experienced and naive wheelchair users. Design: Test-retest study. Setting: Biomechanics laboratory. Participants: Manual wheelchair users (WCUs) (n=10) with 1 to 32 years of wheeling experience and able-bodied (AB) naive users (n=15). Interventions: Not applicable. Main Outcome Measures: Wheelchair propulsion parameters including average peak force, push frequency, push length, and velocity were measured according to the SCP but with 5 trials per session, for 2 sessions. WCUs and AB users were analyzed separately. Intraclass correlation coefficients ([ICC](2,1) and ICC2,5) were calculated to assess intrasession reliability. ICC2,1 and MDC (with 95% confidence) were calculated for each SCP parameter using a single trial from each session and with the mean of 5 repeated measures to evaluate intersession reliability. Results: Intra- and intersession reliability for WCU parameters ranged from high to very high correlation (ICC range, .70-.99). For AB parameters, intrasession ICC2,1 ranged from moderate to very high (ICC range, .50-.92), while intersession ICC2,1 indicated low to very high correlation (ICC range, .25-.90). Estimates of standard error of measurement and MDC were provided for each parameter. For both WCUs and AB users, using the means from 5 trials increased intra- and intersession ICC and decreased MDC values. All MDC values were lower for WCUs compared with AB users. Conclusions: The SCP is a reliable method for assessing propulsion parameters in WCUs, even if just 1 trial is taken per session. AB users showed lower intra- and intersession reliability compared with WCUs. Therefore, for AB users or individuals with minimal wheeling experience, averaging multiple trials is recommended for the SCP.