Understanding racial disparities in prurigo nodularis

To the Editor: We appreciate the interest by Trepanowski et al in our research letter on racial disparities in prurigo nodularis (PN). It should be noted that significant racial disparities are firmly established in PN. Previous studies have found that PN disproportionately affects Black patients—Black patients are 3.4 to 4.4 times more likely to have PN than White patients.1Boozalis E. Tang O. Patel S. et al.Ethnic differences and comorbidities of 909 prurigo nodularis patients.J Am Acad Dermatol. 2018; 79: 714-719.e3Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar,2Whang K.A. Kang S. Kwatra S.G. Inpatient burden of prurigo nodularis in the United States.Medicines (Basel). 2019; 6: 88Crossref PubMed Google Scholar In addition, Black patients with PN are disproportionately affected by disease comorbidities and have evidence for greater systemic inflammation, as reflected by higher peripheral interleukin (IL) 1α, IL-4, IL-5, IL-6, IL-10, IL-17A, IL-22, IL-25, IFN-α, erythrocyte sedimentation rate, C-reactive protein, ferritin, and blood eosinophils.3Sutaria N. Alphonse M.P. Marani M. et al.Cluster analysis of circulating plasma biomarkers in prurigo nodularis reveals a distinct systemic inflammatory signature in African Americans.J Invest Dermatol. 2022; 142: 1300-1308.e3Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar This study was a preliminary investigation into mortality among patients with PN, stratified by racial and ethnic identity. As stated in the article, the comparisons were made only between patients with PN and healthy controls stratified by race/ethnicity and not across groups. Because the reference groups were different for each of these confidence intervals, differences between Black and White patients with PN cannot be directly compared by examining confidence interval overlap, which is not reliable for assessing statistical significance.4Schenker N. Gentleman J.F. On judging the significance of differences by examining the overlap between confidence intervals.Am Stat. 2001; 55: 182-186Crossref Scopus (833) Google Scholar Trepanowski et al suggest a few different statistical methods to determine whether Black patients truly have the highest mortality in PN; however, the TriNetX platform and its limitations preclude many of these techniques. Additionally, the suggested method of stratifying by race and ethnicity prior to propensity score matching was already performed in our original analysis. As outlined in our methods, patients with PN and control patients were stratified by race and ethnicity and then 1:1 propensity score matched by age, sex, race, and ethnicity such that Black patients with PN were compared to Black control patients, and White patients with PN were compared to White control patients. This methodology reinforces the validity of our analysis and findings. We appreciate Trepanowski et al for critically reviewing our work. Black patients continue to be marginalized in health care and research settings, and many of the observed racial disparities are not purely biological; racial differences in socioeconomic, environmental, and health care access are common and are likely to affect disease development, severity, quality of life, and patient outcomes (Fig 1). Investigators must continue to raise awareness and work toward reducing these disparities in health care settings. Dr Kwatra is a member of the board of directors of the Skin of Color Society; is an advisory board member/consultant for AbbVie, Celldex Therapeutics, Galderma, Incyte Corporation, Pfizer Inc, Regeneron Pharmaceuticals, and Kiniksa Pharmaceuticals; and has received grant funding from Galderma, Pfizer Inc, and Kiniksa Pharmaceuticals. Author Sutaria and Dr Semenov have no conflicts of interest to declare. Response to: "Racial disparities in mortality among patients with prurigo nodularis: A multi-center cohort study"Journal of the American Academy of DermatologyVol. 87Issue 3PreviewTo the Editor: The recently published paper by Sutaria et al,1 "Racial Disparities In Mortality Among Patients With Prurigo Nodularis: A Multi-Center Cohort Study," used TriNetX, a health research platform, to investigate differences in all-cause mortality in patients with prurigo nodularis (PN) over a 20-year observation period, with additional stratification by race/ethnicity. The authors reported the following mortality hazard ratios (HRs) for Black (HR, 2.07; 95% CI, 1.64-2.61; P < .001), White (HR, 1.74; 95% CI, 1.52-2.00; P < .001), and Hispanic (HR, 1.62; 95% CI, 1.03-2.54; P = .029) individuals with PN compared with matched controls. Full-Text PDF