Measure for the assessment of confidence with manual wheelchair use (WheelCon-M) version 2.1: reliability and validity.

Objective: To evaluate the measurement properties of the Wheelchair Use Confidence Scale for manual wheelchair users version 2.1 (WheelCon-M 2.1).
Design: Cohort study.
Participants: Volunteer sample of 83 community-dwelling, experienced manual wheelchair users.
Methods: Participants completed the WheelCon-M 2.1 twice to assess retest reliability. Validity was assessed by evaluating hypothesized relationships between the WheelCon-M 2.1 and relevant variables. Responsiveness was assessed using the standard error of measurement (SEM) and smallest real difference (SRD).
Results: The median (interquartile range) WheelCon-M 2.1 score was 84.6 (71.3-92.0) of a possible 0-100. The one-week retest intraclass correlation coefficient was 0.84 with 95% bias-corrected and accelerated confidence intervals of 0.77-0.90. Cronbach's alpha was 0.92. Correlations ranging from rs = -0.19 (p = 0.780) to rs = 0.58 (p < 0.001) were found between the WheelCon-M 2.1 and other relevant outcome measures with all correlations being statistically significant except for age (p = 0.780) and social support (p = 0.057). A statistically significant difference was not found between the sexes (p = 0.140). The SEM and SRM were 5.9 and 16.4, respectively.
Conclusions: WheelCon-M 2.1 has high internal consistency, strong retest reliability, and support for concurrent validity, construct validity and responsiveness. This new test holds promise as a clinical and research tool.