Test-retest reliability and rater agreements of the Assessment of Capacity for Myoelectric Control version 2.0.

• Introduction: The Assessment of Capacity for Myoelectric Control (ACMC) is an observation-based tool that evaluates ability to control a myoelectric prosthetic hand [1]. Validity evidence led to ACMC version 2.0, but test - retest reliability and minimal detectable change (MDC) of ACMC have never been evaluated. For instruments that have an evaluative purpose, such as ACMC, the MDC is a useful clinical value to suggest whether a change is due to measurement error or true change. Investigation of rater agreements in this version was also needed because it has new definitions in certain rating categories and items.Methods: Upper limb prosthesis users (n=25, 13/12 male/female, 15/10 congenital/acquired; mean age 27.5, range 7-72, years) performed one standardized activity twice, 2–5 weeks apart. Activity performances were video-recorded and assessed by two ACMC raters. The item raw scores were converted to Rasch interval ability measures. Ordinal data were analyzed by weighted κ; interval data were analyzed by intraclass correlation coefficient (ICC) and Bland–Altman limit of agreement (LOA) method.Results: For test–retest reliability, ICC2,1 was 0.94. Average weighted κ was 0.76 and percentage agreement (PA) was 85%. In individual items, weighted κ agreements were fair to excellent (0.52・1.00) and PAs were ≥6・100%. MDC95 was ≤.55 logits (1 rater) and 0.69 logits (2 raters). All MDC95 values were ≤5% of the total ability logit range. In the Bland-Altman plot the upper and lower LOA were 0.86 and -0.88 respectively. All except one participant were within the 95% LOA. For inter-rater reliability, weighted κ agreements were fair to excellent in both sessions (0.44–1.00), and ICC2,1 was 0.95 (test) and 0.92 (retest). Intra-rater agreement (rater 1) was excellent (ICC3,1 0.98). The weighted κ values of the test session were all >0.80 and the PAs for each item were ≥6%.Conclusion: The results of the present study demonstrate different aspects of the reliability of ACMC 2.0. Based on these results, we can recommend ACMC as a tool to follow the progress of users in controlling their myoelectric prostheses. The MDC is clinically useful for ACMC raters as a guideline when following the client’s changes over time.

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MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Arbetsterapi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Occupational Therapy (hsv//eng)

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