A Randomized, Blinded Study to Validate the Merz Hand Grading Scale for Use in Live Assessments

Abstract

BACKGROUND: The Merz Hand Grading Scale (MHGS) is a 5-point scale used to grade appearance of the dorsum of the hand. The MHGS has been previously validated for assessment of photographed hands but not for live assessment. OBJECTIVE: The purpose of this randomized, blinded study was to validate the MHGS for live assessment of the hands in the clinical setting. METHODS: Three physician raters completed a scale qualification program that included MHGS training, ratings of standardized hand photographs, and statistical analysis for reliability. Eighty-four subjects (28 males, 30% Fitzpatrick skin Types IV-VI, mean age of 42 years), randomized to 2 live assessment sessions for independent and blinded observation of dorsa of their right hands, completed the study. RESULTS: Overall MHGS intrarater weighted Kappa value was 0.74 (0.68-0.79 [CI 95%]). First- and second-time hand-rating agreement scores ranged from 64% to 75%. Interrater weighed Kappa values ranged from 0.59 to 0.71, representing between-rater paired results of each combination of raters. CONCLUSION: High-weighted Kappa values and agreements demonstrate that consistency at different time points can be achieved individually and by different raters for live assessments. The MHGS is a suitable instrument for live assessment in the clinical setting.