Inter-rater reliability of manual muscle strength testing in ICU survivors and simulated patients

The goal of the paper is to determine inter-rater reliability of trained examiners performing standardized strength assessments using manual muscle testing (MMT). The authors report on 19 trainees undergoing quality assurance within a multi-site prospective cohort study. Inter-rater reliability for specially trained evaluators ("trainees") and a reference rater, performing MMT using both simulated and actual patients recovering from critical illness was evaluated. Across 26 muscle groups tested by 19 trainee-reference rater pairs, the median (interquartile range) percent agreement and intraclass correlation coefficient (ICC; 95% CI) were: 96% (91, 98%) and 0.98 (0.95, 1.00), respectively. Across all 19 pairs, the ICC (95% CI) for the overall composite MMT score was 0.99 (0.98-1.00). When limited to actual patients, the ICC was 1.00 (95% CI 0.99-1.00). The agreement (kappa; 95% CI) in detecting clinically significant weakness was 0.88 (0.44-1.00). MMT has excellent inter-rater reliability in trained examiners and is a reliable method of comprehensively assessing muscle strength.