Reliability of the Charcot-Marie-Tooth functional outcome measure

The CMT-FOM is a 13-item clinical outcome assessment (COA) that measures physical ability in adults with Charcot-Marie-Tooth disease (CMT). Test-retest reliability, internal consistency and convergent validity have been established for the CMT-FOM. This current study sought to establish inter-rater reliability. Following an in-person training of six international clinical evaluators we recruited 10 participants with genetically diagnosed CMT1A, (aged 18-74 years, 6 female). Participants were evaluated using the CMT-FOM over 2 days. Participants were given at least a 3 hour rest between evaluations, and were assessed twice each day. Following the provision of training by master trainers, all 13 items of the CMT-FOM exhibited excellent inter-rater reliability for raw scores (ICC_1,1 0.825-0.989) and z-scores (ICC_1,1 0.762-0.969). Reliability of the CMT-FOM total score was excellent (ICC_1,1 0.983, 95% CI 0.958-0.995). The CMT-FOM is a reliable COA used by clinical evaluators internationally. The next steps are to establish further validation through psychometric evaluation of the CMT-FOM in the Accelerate Clinical Trials in CMT (ACT-CMT) study.