Black patients with psoriasis may undergo skin biopsies at twice the rate of White patients, according to a study.

In the study, published in JAMA Dermatology, researchers from the University of Pennsylvania examined biopsy rates among different racial and ethnic groups. They analyzed data from 10,008 adult patients with psoriasis seen in outpatient dermatology clinics. The study population had a mean age of 55.71 years and was 56.0% female. White patients comprised 70.6% of the cohort, followed by Black (13.1%), Asian or Other Pacific Islander (4.9%), and Hispanic (3.2%) patients.

The cross-sectional study included adults with at least one outpatient dermatology encounter coded for psoriasis (ICD-9 or ICD-10) between January 1, 2010, and December 31, 2019. The primary outcome was performance of at least one skin biopsy for psoriasis. Race and ethnicity data were obtained from electronic medical records.

The researchers used descriptive statistics to summarize patient characteristics across racial and ethnic groups. They employed 1-way analysis of variance for continuous variables and χ2 tests for categorical variables. Multivariable logistic regression was used to calculate adjusted odds ratios and 95% confidence intervals (CI) for the association between race/ethnicity and biopsy receipt.

Overall, 4.8% of the patients received a skin biopsy for psoriasis. However, rates varied significantly by race and ethnicity:

• Black patients: 9.8% 
• Asian or Other Pacific Islander patients: 4.7%
• White patients: 4.1%
• Patients of unknown race: 4.0%
• Hispanic patients: 3.7%
• Patients of other races: 1.6%

In adjusted analyses, Black patients had 2.03 times higher risk (95% CI = 1.54–2.65) of receiving a skin biopsy for psoriasis compared with White patients. The association remained significant after controlling for sociodemographic factors and health care utilization.

Demographic analysis revealed variations across racial and ethnic groups. The mean age was highest among White patients (56.80 years) and lowest among Asian or Other Pacific Islander patients (46.97 years). The proportion of female patients was highest among Black patients (65.3%) and lowest among Asian or Other Pacific Islander patients (51.4%).

Socioeconomic factors also differed. Commercial insurance was most common among Asian or Other Pacific Islander patients (64.4%) and White patients (61.1%), whereas Medicaid was most prevalent among Hispanic patients (36.3%) and Black patients (29.1%). The median household income was highest for White patients ($78,800) and lowest for Black patients ($39,920). The percentage of college-educated individuals in patients' neighborhoods was highest for White patients (44.63%) and lowest for Black patients (23.68%).

Health care utilization patterns showed some variation. Visits to psoriasis specialists ranged from 37.6% for Black patients to 48.4% for Asian or Other Pacific Islander patients. Mean dermatology visits per year were relatively consistent across groups (range = 1.88–2.00). Mean dermatology follow-up time was longest for White patients (2.78 years) and shortest for Hispanic patients (1.75 years).

The multivariable logistic regression model, which adjusted for various demographic and clinical factors, revealed several significant associations:

• Older age was associated with higher odds of biopsy (odds ratio [OR] = 1.01, 95% CI = 1.01–1.02 per year increase)
• Being single vs married increased biopsy likelihood (OR = 1.31, 95% CI = 1.04–1.65)
• Having seen a psoriasis expert was associated with higher odds of biopsy (OR = 1.25, 95% CI = 1.03–1.52)
• Longer mean follow-up time increased biopsy likelihood (OR = 1.15, 95% CI = 1.11–1.19 per year)
• Patients who had mixed insurance types had a higher risk of receiving a biopsy (OR = 1.97, 95% CI = 1.34–2.83) compared with those who had commercial insurance.

Sex was not significantly associated with biopsy likelihood (OR among males = 0.88, 95% CI = 0.72–1.07). Additionally, median household income and college education percentage were not significantly associated with biopsy likelihood.

The researchers conducted sensitivity analyses using both narrower and broader definitions of psoriasis biopsies, finding consistent results across these analyses.

They noted several study limitations, including that the evaluation of an urban academic practice may not be representative of other settings. They also noted potential uncertainty in the validity of algorithms used to identify psoriasis skin biopsies.

The study was deemed exempt by the institutional review board of the University of Pennsylvania and followed the STROBE reporting guideline for observational studies.

"These findings add to the limited literature on diagnostic practices by patient race and ethnicity in the clinical setting," underscored the study authors. They reported that their results confirmed similar findings from a smaller prior study and provided detailed information on the associations between specific racial and ethnic groups and the likelihood of skin biopsy for psoriasis.

The researchers concluded that further research is needed to understand the factors contributing to these observed differences in biopsy rates and to examine potential implications for psoriasis diagnosis and management across diverse patient populations.

Conflict of interest disclosures can be found in the study.