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A Randomized, Blinded Study to Validate the Merz Hand Grading Scale for Use in Live Assessments
Joel L Cohen1, Alastair Carruthers, Derek H Jones
1*AboutSkin Dermatology and DermSurgery, Englewood, Colorado, and Department of Dermatology, University of Colorado, Aurora, Colorado; †Department of Dermatology and Skin Science, University of British Columbia, Vancouver, Canada; ‡Skin Care and Laser Physicians of Beverly Hills, Los Angeles, California; §Bay Area Laser Institute, San Francisco, California; ‖Merz North America, Raleigh, North Carolina; ¶Yardley, Pennsylvania; #San Francisco, California.
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.
