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

Abstract

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. The purpose of this randomized, blinded study was to validate the MHGS for live assessment of the hands in the clinical setting. 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. 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. 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.