Melasma is a disorder of pigmentation commonly affecting women with darker skin types.1 Owing to the recalcitrant nature of melasma, more randomized controlled clinical trials of new treatment modalities are needed. These trials require precise categorization of disease severity to select appropriate patients for enrollment and determine response to treatment. The Melasma Area and Severity Index (MASI) is the most common outcome measure used for melasma studies, and was validated 20 years after it was first reported.2,3 This validation process eliminated homogeneity as a part of the MASI, resulting in the new modified MASI score (mMASI).3
Calculation of the mMASI score is performed by rating darkness and area of involvement of 4 areas of the face. These figures are then inserted into an equation, resulting in the final mMASI score (Table).
Despite the development of the mMASI score, a global severity score is also needed to determine optimal outcomes in clinical trials in melasma. Global scores are commonly used in clinical research studies and are intended to provide a clinically meaningful snapshot of disease severity that is easily understandable to physicians and patients. The melasma severity score (MSS) has been used in large trials as a global score.4 The MSS has 4 grades of severity (clear, mild, moderate, severe), with clear or mild as ideal outcomes in trials of patients with moderate to severe melasma.4 This is important to clinicians because treatments that show a significant reduction of moderate to severe melasma to clear or mild melasma are favored by patients.4 However, the correlation of the mMASI to MSS categories is unknown. We sought to stratify the mMASI into ranges correlating with mild, moderate, and severe melasma so that clinicians can better interpret melasma studies and investigators can identify patients with moderate to severe melasma by correlating MSS categories to mMASI scores.
Data for 79 patients with melasma were retrospectively reviewed in this study approved by the University of Texas Southwestern Medical Center institutional review board. Melasma for all patients had been scored using the MSS, MASI, and mMASI. The data were analyzed by comparing the results of the MSS scores to the MASI and mMASI to determine if distinct ranges for mild, moderate, and severe melasma existed.
One-way analysis of variance (ANOVA) was used to examine mMASI and MASI by MSS group. Assumptions of ANOVA (equal group variance and normality) were checked. When the ANOVA was significant, the Bonferroni post hoc test was performed. SPSS software (version 21) was used for analyses, and Sigma Plot (version 12.5) was used to produce the figures.
The MSS groups for mMASI were found to be significantly different (P < .001; partial η2 = 0.42) (Figure). All pairwise Bonferroni post hoc tests were significant (P < .001); the means for mMASI were the highest for those with severe MSS and the lowest for those with mild MSS (means: mild, 3.8 [95% CI, 2.7-4.9]; moderate, 6.5 [95% CI, 5.8-7.2]; severe, 8.9 [95% CI, 8.0-9.8]).
The MSS groups for MASI were also found to be significantly different (P < .001; partial η2 = 0.60) (Figure). All pairwise Bonferroni post hoc tests were significant (P < .001); the means for MASI were highest for those with severe MSS and the lowest for those with mild MSS (means: mild, 6.9 [95% CI, 4.9-8.8]; moderate, 12.4 [95 CI, 11.1-13.7]; severe, 20.2 [95% CI, 18.6-21.9]).
This study provides a framework that facilitates meaningful clinical interpretation of the numerical mMASI score. The ranges for mMASI provided herein correspond to global levels of severity using the MSS. Such categorization in MSS levels can assist clinicians in interpreting clinical trial data, severity of disease, and response to treatment. The mMASI is a simple, reliable validated tool that is a modification of the most commonly used outcome measure for melasma. This user-friendly tool can now be correlated with the newly proposed clinical ranges of severity presented in the Figure, which can be used to assist researchers in determining entry criteria for clinical trains for melasma and improvement of melasma with treatment.
Corresponding Author: Amit G. Pandya, MD, Department of Dermatology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9069 (amit.pandya@utsouthwestern.edu).
Published Online: May 4, 2016. doi:10.1001/jamadermatol.2016.1006.
Author Contributions: Dr Pandya had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. The authors are responsible for the accuracy of the information presented.
Study concept and design: Pandya.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Rodrigues, Ayala-Cortés, Rodríguez-Arámbula.
Critical revision of the manuscript for important intellectual content: Rodrigues, Ayala-Cortés, Hynan, Pandya.
Statistical analysis: Hynan.
Administrative, technical, or material support: Ayala-Cortés, Pandya.
Study supervision: Rodrigues, Ayala-Cortés, Pandya.
Conflict of Interest Disclosures: None reported.
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