Efficacy of a dermocosmetic skin care regimen in reducing acne‐associated post‐inflammatory hyperpigmentation in subjects with phototypes IV to VI

Post-inflammatory hyperpigmentation (PIH) is a challenge in acne, mainly in subjects with Fitzpatrick skin phototypes types IV to VI and PIH. Acne PIH is characterized by increased skin pigmentation following inflammation, being more prevalent among people with skin of colour due to heightened melanin response. Approximately 58% of these acne patients have PIH lasting 1 year or more in more than half of the subjects and 5 years or longer in 22.3% of subjects.1 Beyond its aesthetical impact, PIH may affect the quality of life, leading to psychological distress and reduced self-esteem.2 To address this concern, we conducted a study in Mauritius in subjects with a phototype IV to VI with mild to moderate acne, assessing the efficacy of a dermocosmetic cream (DC), comprising salicylic acid, lipohydroxy acid, niacinamide, procerad, mannose and APF (a biomass of Vitreoscilla filiformis grown in La Roche-Posay Thermal-Spring-Water culture medium), applied twice daily for 8 weeks, along with an acne-dedicated cleanser (Effaclar® Purifying foaming gel and Effaclar® Duo+; La Roche-Posay Laboratoire Dermatologique), using the Global Evaluation of Acne scale.3 According to local regulatory guidelines, this study did not require approval from local ethics committees. However, all subjects gave written informed consent to participate and for the use of their photographs. The study complied with the principles of the Declaration of Helsinki. In this 8-week, single-arm clinical study, standardized high-quality face profile images of 43 subjects were reviewed by a blinded independent dermatologist. The mean age was 19.2 years (ranging from 11 to 42 years), 47% were aged less than 18 years, 51% had a phototype V (19% phototype VI) and 60% were females. The number of PIH marks was assessed, as well as the global PIH severity and hyperpigmentation intensity, using 9 and 6-grade ordinal scales, respectively.4 A reduction of 19.7% of PIH lesions at day 56 (28.6 ± 9.33 lesions) compared to baseline (35.6 ± 12.96 lesions; mean difference = 7.0 lesions, p < 0.001) was observed. The observed 5% decrease in global PIH severity (mean difference = 0.24 points, p = 0.174) and the 6% decrease in pigmentation intensity (mean difference = 0.2, points p = 0.081) showed a trend towards improvement but were not statistically significant at Day 56. These observations are consistent with previous research on the efficacy of salicylic acid, lipohydroxy acid and niacinamide in treating PIH or pigmentary disorders, while suggesting potential benefits from the other components in the DC formula.5, 6 For instance, niacinamide works by inhibiting melanosome transfer from melanocytes to keratinocytes.6 Figure 1 displays an example of significant improvement in PIH after the 8-week treatment. The study also showed the limitations of current methods for assessing global PIH severity and hyperpigmentation intensity. The subjective nature of current scales, or their complexity, even when used by a trained dermatologist using high-quality images, makes the evaluation of PIH challenging. The main issues experienced during the study were difficulties in identifying PIH in the presence of residual active inflammatory lesions and the high diversity in size and density of marks, making some evaluation tools difficult to use.7 The complexity of using these scales may have significantly impacted the statistical power of the study and the reduced sample size may have limited the power of the study. However, this study confirmed the efficacy of a specific DC skin care regimen in reducing PIH marks after 56 days of use in subjects with skin of colour and mild to moderate acne. However, it also highlights challenges in evaluating PIH emphasizing the need for improved assessment tools. Margot Nioré developed the protocol and managed the study. Samir Salah analysed the data. Michael Benzaquen acted as investigator for the study. Delphine Kerob provided medical advice. All authors participated in the analysis of study results and in the writing of the publication. The authors acknowledge Karl Patrick Göritz, SMWS, France, for the writing support. This study was supported by La Roche-Posay Laboratoire Dermatologique. Samir Salah, Margot Nioré and Delphine Kerob are employees of La Roche-Posay Laboratoire Dermatologique. Michael Benzaquen serves as a consultant to La Roche-Posay Laboratoire Dermatologique. All patients in this manuscript have given written informed consent for participation in the study and the use of their deidentified, anonymized, aggregated data and their case details (including photographs) for publication. The study was conducted in Mauritius from March 2020 to August 2020. According to local regulatory guidelines of Mauritius, this type of studies testing marketed cosmetics for which the sponsor assures the safety, did not require approval from local ethics committees. The study complied with the principles of the Declaration of Helsinki and conformed to good clinical practices.