To the Editor:
Dyspigmentation, specifically hyperpigmentation or post-inflammatory hyperpigmentation (PIH), disproportionately affects those with skin of color. Studies show that dyschromias, including PIH, are one of the most common presenting complaints of darker-skinned racial ethnic groups when visiting a dermatologist.1 Vashi et al found that Black, Hispanic, and Asian women reported their symptoms of PIH more bothersome than White women, and non-White women were also more likely to be concerned with clearing their hyperpigmentation compared to white women (41.6% vs 8.4%, respectively).2 Post-inflammatory hyperpigmentation (PIH) is a reactive hypermelanosis and sequela of a variety of inflammatory skin conditions and can have a negative impact on a patient's quality of life, particularly for darker-skinned patients. This is likely due to increased production or deposition of melanin into the epidermis or dermis by labile melanocytes.1
Of the 16 included studies, only 31.3% (5/16) reported participant race. White participants accounted for 38.8% (91/234) of those studies, Black/African American participants accounted for 30.3% (71/234), Hispanic participants accounted for 28.6% (67/234), and "other" accounted for 2.1% (5/234). Of the five studies that reported race, 20% (1/5) subsequently categorized participants by Fitzpatrick skin types.
Moreover, some studies stratified their participants by Fitzpatrick skin typing in lieu of race. The original Fitzpatrick scale was created in 1975 to classify the reactivity of white skin to ultraviolet A phototherapy. The scale was later updated to include nonwhite patients, adding two categories initially based on color alone and later with tanning reactions: 'brown' (type V) and 'black' (type VI). Now, as the standard skin classification system, it is often incorrectly used as a proxy for race/ethnicity.5 Stratifying patients by the Fitzpatrick scale is problematic because certain racial or ethnic groups may contain individuals who span the entire scale. Therefore, a clinical trial may include a variety of skin types, but still not be racially diverse.
Depigmenting agents often include hydroquinone, azelaic acid, kojic acid, arbutin, and certain licorice (glycyrrhiza) extracts. Other agents include retinoids, mequinol, ascorbic acid (vitamin C), and niacinamide, many of which are available as over-the-counter cosmeceuticals and commonly used by patients.1 Herein, we sought to evaluate published hyperpigmentation clinical trials, both industry-sponsored and investigator-initiated, to determine the racial diversity of patients over the past two decades.
A search was conducted using the ClinicalTrials.gov website and the search terms "Hyperpigmentation" AND "Post-Inflammatory Hyperpigmentation" to determine clinical trials that occurred between January 2002 and January 2022. Studies were only included if they had trial sites in the United States. Two independent authors (JD and CO) reviewed the included studies for data collection, and discrepancies were resolved through consensus discussion. Sixteen (16) total clinical trials met the inclusion criteria.
Of the 16 included studies, only 31.3% (5/16) reported participant race. White participants accounted for 38.8% (91/234) of those studies, Black/African American participants accounted for 30.3% (71/234), Hispanic participants accounted for 28.6% (67/234), and "other" accounted for 2.1% (5/234). Of the five studies that reported race, 20% (1/5) subsequently categorized participants by Fitzpatrick skin types.
Notably, of the studies that did not report participant race, 27.3% (3/11) studies included Fitzpatrick skin types. Of these three studies, 0% (0/79) of the participants had Fitzpatrick Skin Type 1, 22.8% (18/79) had Fitzpatrick Skin Type II, 16.5% (13/79) had Fitzpatrick Skin Type III, 24.1% (19/79) had Fitzpatrick Skin Type IV, 30.4% (24/79) had Fitzpatrick Skin Type V, and 6.3% (5/79) had Fitzpatrick Skin Type VI.
The US Census population projections confirm that by 2045, non-white communities will be the majority, while whites will comprise 49.7% of the population.3 Therefore, diverse research cohorts are important in all aspects of dermatological clinical trials. In 2017, the NIH updated its policy to include a requirement that recipients conducting applicable NIH-defined Phase III clinical trials ensure the results of valid analyses by sex/gender, race, and or/ethnicity by submitting this information to ClinicalTrials.gov.4 Despite NIH mandates4, our study underscores that there is still minimal reporting of ethnic and racial data. Notably, 68.8% of the included studies in this report did not detail race or ethnicity at all.
Moreover, some studies stratified their participants by Fitzpatrick skin typing in lieu of race. The original Fitzpatrick scale was created in 1975 to classify the reactivity of white skin to ultraviolet A phototherapy. The scale was later updated to include nonwhite patients, adding two categories initially based on color alone and later with tanning reactions: 'brown' (type V) and 'black' (type VI). Now, as the standard skin classification system, it is often incorrectly used as a proxy for race/ethnicity.5 Stratifying patients by the Fitzpatrick scale is problematic because certain racial or ethnic groups may contain individuals who span the entire scale. Therefore, a clinical trial may include a variety of skin types, but still not be racially diverse.
