Reliability study for the Japanese version of the Columbia Muscle Cramp Scale in amyotrophic lateral sclerosis

Background The Columbia Muscle Cramp Scale (CMCS) is a useful tool for evaluating muscle cramps commonly observed in patients with amyotrophic lateral sclerosis (ALS). The CMCS comprises five subdomains: triggering factors, frequency, location, severity, and the degree to which cramps affect overall daily living. Aim This study aimed to evaluate the reliability of the CMCS, which was translated into Japanese. Methods Thirty patients with ALS (17 men and 13 women) from seven facilities were evaluated twice by two different evaluators (doctors, nurses, physical therapists, occupational therapists, and speech‐language‐hearing therapists). The degree of inter‐ and intra‐rater agreement was evaluated using kappa statistics. Weighted kappa statistics and 95% confidence intervals accounted for multiple‐order responses. Results The average age was 60.4 (standard deviation: 10.4, range: 39–77) years. The kappa statistics for the inter‐rater reliability of the CMCS items showed moderate to very good agreement, ranging from 0.56 (cramp triggering) to 0.91 (daily activity) at visit 1 and 0.51 (severity) to 0.96 (daily activity) at visit 2. The kappa statistics for the intra‐rater reliability of the CMCS items also showed moderate to good agreement, ranging from 0.45 (frequency) to 0.79 (cramp triggering). Conclusion The Japanese version of the CMCS demonstrated intra‐ and inter‐rater reliability agreement and is expected to be useful for evaluating muscle cramps in patients with ALS.