Skin phototype of participants in laser and light treatments of cosmetic dermatologic conditions: A systematic review

In cosmetic dermatology, lasers and lights treat a variety of hair and skin conditions, including some that disproportionately affect people of color.


| INTRODUC TI ON
The racial and ethnic diversity of the United States is increasing, with projections estimating that more than 50% of the U.S. population is set to identify as Hispanic or nonwhite by 2045. 1 Similarly, by 2044, more than 50% of the US population will have skin of color, denoted as skin phototypes 4-6. 2 Given these changes, there is significant concern across the medical field that clinical trials are not representative of this racial and ethnic diversity. 3 In cosmetic dermatology, lasers and lights are used to treat a variety of hair and skin conditions, including some that disproportionately affect people of color. 4 While some laser and light devices have been shown to be harmful in skin of color, other devices have not been investigated or lack sufficient evidence to support safety for use in skin of color. 4 The lack of information has important consequences for clinical practice, as clinicians are unable to counsel patients on the efficacy and possible complications of various devices in patient with skin of color.

| Data abstraction
The full text of all eligible articles was reviewed, and the following data were collected from each RCT: journal of publication, condition of study, laser or light treatment(s) studied, funding type (industry, foundation/nonprofit, government, university, hospital, nonlisted, or none), location of study (inside or outside the United States), total number of participants, reporting of participant gender, reporting of participant racial/ethnic composition, and reporting of skin phototype. Further data were collected to identify percentage of nonwhite or Hispanic participants and skin of color participants in each RCT.

| Statistical analysis
Descriptive statistics with means were computed for all continuous variables and counts with percentages were computed for all nominal variables. Categorical variables were compared using Pearson's chi-squared, Fischer's exact, or Student's t-tests as appropriate.
Statistical significance was set at p < 0.05.

| General characteristics
A total of 17 948 results were obtained from the initial search. After duplicate articles (n = 2489) were removed and inclusion and exclusion criteria were applied, ultimately 461 unique randomized controlled trials containing 14 763 participants were included ( Figure 1).

| Skin of color representation by laser
In studies of CO 2 lasers, 76.6% (n = 49) reported skin phototype of      While there broadly appears to be skin of color representation, a more granular understanding of the data shows a large discrepancy in representation between "lighter" and "darker" skin of color patients.

| Skin of color representation by journal
The skin of color representation varied by the condition of study, study location, and journal of publishing. Melasma and scarring both disproportionately affect skin of color patients and accounted for almost half of all RCTs that included participants with skin phototypes 5 or 6. 8,9 However, skin phototype 5 and 6 representation was significantly less in studies of conditions with no known racial or skin-type predilection, such as port-wine stains. 10 Although it is  Our analysis has several limitations. Approximately 25% of RCTs in this study did not report the skin phototype of participants, and 82% of U.S. trials did not report the race or ethnicity of participants.
Additionally, many trials did not provide information regarding the skin tone of individual participants. As a result, our analysis of skin

ACK N OWLED G M ENTS
Study data were collected and managed using REDCap electronic data capture tools hosted at Boston University, CTSI 1UL1TR001430.

CO N FLI C T O F I NTE R E S T S TATE M E NT
None declared.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.

E TH I C S S TATEM ENT
This study is exempt from Institutional Review Board approval.