Measurement and prediction of the severity of postinflammatory dyspigmentation after resolution of psoriatic plaques in patients treated with biologic therapy.

To the Editor: Advances in psoriasis therapy have made “clear” or “almost clear” skin a more achievable goal for the majority of patients.1Warren R.B. Gooderham M. Burge R. et al.Comparison of cumulative clinical benefits of biologics for the treatment of psoriasis over 16 weeks: results from a network meta-analysis.J Am Acad Dermatol. 2020; 82: 1138-1149Google Scholar Postinflammatory dyspigmentation (PID) is commonly observed in skin previously affected by psoriasis.2Maria P.S. Valenzuela F. Morales C. la Fuente R. Cullen R. Lentiginous eruption in resolving psoriasis plaques during treatment with ixekizumab: a case report and review of the literature.Dermatol Reports. 2017; 9: 7079Google Scholar We surveyed the impact of PID among 237 patients with psoriasis who were regularly followed and achieved “clear” or “almost clear” skin after biologic therapy (survey response rate, 92.2%; Supplemental Table 1 is available via Mendeley at https://data.mendeley.com/datasets/dgpch66rb7/1). More than 80% of patients considered PID an important, neglected problem, and 73% thought there was an unmet treatment need for PID (Fig 1). We developed the PID area and severity index (PIDASI), which includes 2 characteristics of dyspigmentation (intensity and heterogeneity) and the area involved (Fig 2). The sum of the rating for intensity and heterogeneity was multiplied by the numerical value of the areas involved and by the weighting for each respective area. Four raters independently scored the severity of PID using both the PIDASI and Global Severity Score (Supplemental Table 2). The MX 18 Mexameter was used to measure the differences in the pigmentation of involved and adjacent uninvolved skin, to determine the melanin index3Clarys P. Alewaeters K. Lambrecht R. Barel A.O. Skin color measurements: comparison between three instruments: the Chromameter(R), the DermaSpectrometer(R) and the Mexameter(R).Skin Res Technol. 2000; 6: 230-238Google Scholar for 3 representative PID lesions within 1 randomly selected body area (face and neck, upper limb, trunk, or lower limb). The PIDASI demonstrated excellent intrarater reliability (intraclass correlation coefficients, 0.968-0.975; Supplemental Table 3) and inter-rater reliability (intraclass correlation coefficients, 0.956-0.963) in the patients with PID (Supplemental Table 4). With regard to validity, the PIDASI intensity scores correlated strongly with the Mexameter measurements for each rater (Supplemental Table 5) and Global Severity Score scores (r = 0.866, P < .001). Moreover, moderate correlations were observed between the absolute value of PIDASI and Skin Discoloration Impact Evaluation Questionnaire4Balkrishnan R. Kelly A.P. McMichael A. Torok H. Improved quality of life with effective treatment of facial melasma: the pigment trial.J Drugs Dermatol. 2004; 3: 377-381Google Scholar (r = 0.405, P < .001), and the absolute value of PIDASI and Dermatology Life Quality Index (r = 0.365, P < .001). Multivariate linear regression analysis was used to identify the risk factors associated with PID. Longer psoriatic disease duration, higher psoriatic disease severity, old age, freckles, and melasma were associated with more severe postinflammatory hyperpigmentation (PIH), while hair whitening was associated with hypopigmentation (Supplemental Table 6). Our result supports that the degree and burden of underlying inflammation more profoundly impact the severity of PIH after the resolution of psoriasis than conventional risk factors. A significant relationship between sun exposure and PIH is unlikely because exposure to ultraviolet light provides a therapeutic effect in psoriasis by partly mitigating the degree of inflammation and subsequent inflammation-induced hyperpigmentation. Patients with hair whitening were prone to postinflammatory hypopigmentation, likely because hair whitening may be an individual indictor of decreased resistance of melanocytes to environmental stress or stimuli, such as inflammation.5Ruiz-Maldonado R. Orozco-Covarrubias M.L. Postinflammatory hypopigmentation and hyperpigmentation.Semin Cutan Med Surg. 1997; 16: 36-43Google Scholar Our study was limited by only inclusion of an Asian cohort with psoriasis and further validation is still recommended before wider application. Nevertheless, our study demonstrated that PID after the resolution of psoriatic plaques is an unmet need that warrants additional attention and therapies. The PIDASI provides a reliable and valid instrument for the assessment of PID. Dr. Chiu received speaking fees from AbbVie, Novartis Pharmaceuticals Corporation, Janssen-Cilag Pharmaceutica, Eli-Lilly, Kyowa Hakko Kirin Taiwan, and Pfizer Limited and conducted clinical trials for Eli-Lilly and Sanofi Pharmaceuticals. Dr, Huang has conducted clinical trials while serving as a principal investigator for Galderma, Eli-Lilly, Novartis Pharmaceuticals Corporation, and Janssen-Cilag Pharmaceutica; received honoraria for serving as an advisory board member for Pfizer Limited, AbbVie, and Celgene; and received speaking fees from AbbVie, Eli-Lilly, and Novartis Pharmaceuticals Corporation. Dr. Liao has received speaking fees from AbbVie, Novartis, Eli-Lilly Pharmaceuticals Corporation, Janssen-Cilag Pharmaceutica, and Leo Pharm.