Self-applied topical interventions for melasma: a systematic review and meta-analysis of data from randomized, investigator-blinded clinical trials

Abstract

Background: Melasma is a common dermatological condition. Although its relevance as a skin condition is primarily of a cosmetic nature, it may affect the patient's wellbeing and quality of life. A broad range of treatment options is available, which makes it difficult to choose the most appropriate of those treatments.

Objectives: To summarize and critically appraise evidence from investigator-blinded randomized controlled trials (RCTs) on the efficacy and safety of self-applied topical interventions for melasma.

Methods: We systematically searched MEDLINE and the Cochrane CENTRAL trials database for RCTs on topical, self-administered interventions for patients diagnosed with melasma. Eligibility was limited to RCTs that explicitly stated in their methods section (i) how they generated the random allocation sequence, and (ii) that the study outcome assessor was blinded to the participants' group allocation. Outcomes of interest included evaluator-assessed clinical scores (such as the Melasma Area and Severity Index), quality of life and patient-reported outcomes, as well as safety outcomes. The study findings were meta-analysed, pooling data from studies on the same comparisons, if this was possible. We assessed confidence in effect estimates using the GRADE approach.

Results: Our searches yielded 1078 hits. We included 36 studies reporting on 47 different comparisons of interventions. These included medical treatments such as 'triple combination cream' (TCC), over-the-counter cosmetic and herbal products, as well as sun creams covering different light spectra. Pooling data was possible for only two comparisons, topical tranexamic acid (TXA) vs. hydroquinone (HQ) and cysteamine vs. placebo. Direct comparisons were available for a variety of interventions; however, the reported outcomes varied greatly. Overall, our confidence in the effect estimates ranged from very low to high.

Conclusions: Our findings indicate that TCC and its individual components HQ and tretinoin are effective in lightening melasma. Besides these established self-applied treatment options, we identified further medical treatments as well as promising cosmetic and herbal product treatment approaches. Furthermore, evidence suggests that using broad-spectrum sunscreen covering both the visible and ultraviolet-light spectrum enhances the treatment efficacy of HQ. However, with mostly small RCTs comparing treatments directly using a broad range of outcomes, further research is needed to draw conclusions about which treatment is most effective. What is already known about this topic? Melasma is a common dermatological disease. Although it is primarily a cosmetic condition, it can severely affect the patient's wellbeing and quality of life. Treatment options for melasma include a broad range of medical, cosmetic and herbal products. Given the large number of available interventions, it is difficult for clinicians and for patients to make informed decisions about which treatment to choose. What does this study add? We systematically assessed data from investigator-blinded randomized controlled trials of self-applied topical interventions. Our GRADE evaluations of confidence in the findings ranged from very low to high and may help clinicians and patients navigate treatment decisions. Besides the established self-applied medical treatment options, we identified promising cosmetic and herbal treatment approaches. Evidence suggests sunscreen covering the ultraviolet (UV)- and visible light spectra increases treatment efficacy compared with UV-only protection.