Abstract
Background:
Psoriasis affects ~3% of the adult U.S. population, with known differences in prevalence, presentation, and treatment outcomes across racial and ethnic groups. In pediatric populations, disparities in psoriasis recognition may lead to delayed diagnosis and undertreatment, especially in patients with skin of color (SoC).
Objectives:
To compare clinical presentation and treatment patterns in pediatric patients with psoriasis with and without SoC at a single tertiary-care pediatric center.
Methods:
We conducted a retrospective, case–control cohort study of patients diagnosed with psoriasis (including TNF-associated psoriasis) before age 18 at SickKids Hospital (January 2008-March 2024). Inclusion criteria were systemic treatment before or after diagnosis of psoriasis and available photo documentation. Patients were stratified by skin phototype based on the Massey-Martin Scale for SoC. Demographics, clinical features, and treatment patterns were compared between SoC and non-SoC groups.
Results:
Among 115 patients, 42.6% were classified as SoC. Scalp involvement (P = .008), inflammatory bowel disease (P = .05), and arthritis were more common in non-SoC patients. SoC patients had a shorter time to diagnosis and were more likely to receive cyclosporine initially and methotrexate overall. Non-SoC patients had higher biologic use throughout care (77.2% vs 63.2%). Topical corticosteroids were the most prescribed treatment across both groups.
Conclusions:
Pediatric patients with and without SoC showed distinct trends in disease presentation and management. Differences in clinical presentation and medication use highlight the need for increased awareness of psoriasis manifestations in diverse skin types. Prospective studies with standardized assessment tools could help addressing the differences described in this study.
Introduction
Psoriasis is a chronic immune-mediated disorder with variable prevalence depending on ethnicity and geographic location. 1 It affects 3% of the adult U.S. population, with higher rates in White individuals at 3.6%, followed by other racial/ethnic groups (non-Hispanic, including multiracial) at 3.1%, Asian individuals at 2.5%, Hispanic individuals at 1.9%, and Black individuals at 1.5%. 2 Among children, the rate is estimated at 128 cases/100 000 individuals. 3
The most common presentation of adult psoriasis is chronic plaque type 1 ; however, its morphology, treatment, and impact on quality of life vary across different racial/ethnic groups. 4 In both adult and pediatric Black patients, it usually presents with less erythema, thicker plaques, more scaling, greater body involvement, and increased risk of postinflammatory changes.4,5 Scalp psoriasis tends to be more severe in Asian and Black patients, particularly in Black women 4 requiring unique treatment considerations to accommodate hair texture, cultural hair styling practices, and frequency of hair washing. 1 Asian patients typically experience less severe psoriasis, often described as “small plaque” psoriasis.1,6 In a cross-sectional single-institution study, Asian patients were more likely to present with erythrodermic or pustular psoriasis compared to White patients. In this same study, Hispanic patients were also more likely to present with pustular psoriasis. 7
Both adult and pediatric patients with skin of color (SoC) may face treatment delays due to differences in clinical presentation, access to care, and cultural influences on treatment preferences, 4 which may negatively affect treatment outcomes.
At our institution, we follow patients with psoriasis from diverse racial/ethnic groups. We document their disease through photo documentation at each visit, including at baseline, enabling us to compare and track treatment responses effectively.
Materials and Methods
This was a retrospective, case-control cohort study of patients with psoriasis diagnosed before 18 years of age seen at the Dermatology department at SickKids Hospital from January 2008 to March 2024. We included patients with psoriasis who were seen in clinic at SickKids Hospital and had received systemic treatment at any time. Patients who developed psoriasiform disease secondary to systemic treatment were also included. Patients without photos of cutaneous manifestations were excluded. Ethics approval was obtained from our institution. Cases were patients with SoC defined by a color rating of 4 or more on the Massey-Martin Skin Color Guide. Controls were the rest of the psoriasis cohort.
Patients were identified using our master list of individuals with psoriasis and searching for pictures in our photo database and subsequently selected based on above inclusion and exclusion criteria. Data were extracted from our electronic clinical database.
Results
A total of 115 charts and photos were reviewed (Table 1). Of these, 42.6% had phototype equal or higher than 4, being classified as SoC, and 66 patients had phototypes between 1 and 3, being classified as non-SoC. Among the cohort, there was female predominance in both groups and higher proportion in the SoC group (71.4% vs 60.6%). The mean age of onset was 7.52 years, while the mean age of diagnosis was 10.1 years, with no significant difference between both groups. Most patients had body surface area (BSA) under 10% on the first appointment, with similar percentages between both groups. SoC patients had a higher proportion of 10% to 49% involvement, and a smaller proportion of over 50% involvement (8.1%) though this was not statistically significant.
Clinical and Demographic Characteristics of Patients.
Abbreviations: BSA, body surface area; IBD, inflammatory bowel disease.
Plaque psoriasis was the most prevalent subtype overall, affecting 73% of patients, and more prevalent in non-SoC (77.27% vs 67.35%, P = .24). Genital involvement was slightly more prevalent in patients with SoC (16.7% vs 19.6%, P = .69). Nail involvement was observed in 12.5% of patients, with similar prevalence between groups. (Table 1) Scalp involvement was observed in 53% of patients and was significantly more common in the non-SoC group, and this was statistically significant (63.6% vs 38.8%, P = .008).
Inflammatory bowel disease (IBD) prevalence was also increased in the non-SOC group (27.3% vs 12.2%, P = .05). Though not statistically significant, arthritis was also more predominant in the non-SoC group (16.7% vs 8.2%, P = .181). Among patients with concurrent arthritis (n = 15), a greater proportion of SoC patients were treated with TNF-α inhibitors compared to non-SoC patients (75% vs 45%, P = .569; Table 2). All SoC patients with IBD were being treated with TNF-α inhibitors on the first appointment compared to 72% of non-SoC patients (P = .28). The overall prevalence of paradoxical psoriasis between SoC and non-SoC was not clinically significant between our cohorts (30.3% vs 18.4%, P = .145).
TNF Inhibitor Use by Condition and Skin Type in Patients With Psoriasis.
Abbreviation: IBD, inflammatory bowel disease.
Comparison between skin of color and nonskin of color within that specific condition.
With regards to management, patients with SoC demonstrated a higher trend in receiving systemic treatments at their first appointment, particularly cyclosporine (8.1% vs 1.5%, P = .16; Table 3). In contrast, non-SoC patients were more likely to receive biologics initially (10.6% vs 8.2%, P = .09) and throughout care, with 77.2% on biologics at last follow-up compared to 63.2% of SoC patients (P = .10). Both groups had similar rates of oral methotrexate use at first appointment, though SoC patients were more likely to use it over time. The non-SoC group more frequently received acitretin or subcutaneous methotrexate. Topical corticosteroids were the most used therapy in both groups, with a slightly higher use in non-SoC patients in the first appointment (54.5% vs 51%, P = .52) and in SoC patients at the last follow-up (83.6% vs 75.7%, P = .30). Topical calcineurin inhibitors were more frequently used in patients with non-SoC overall.
Treatments at Initial Appointment and Last Follow-Up.
Abbreviations: SoC, skin of color; PO, by mouth; SC, subcutaneous.
Discussion
This retrospective study analyzed both psoriasis and paradoxical psoriasis secondary to TNF-α inhibitors in pediatric patients with SoC and non-SoC. The primary objective was in characterizing the overall psoriasis burden and valuable trends in associated systemic disease and treatment.
A study conducted by Dickerson et al. demonstrated that patients with SoC waited 3.23 times longer for psoriasis diagnosis compared to non-SoC. 8 According to the authors, this could be due to several factors, including physician’s unfamiliarity with diverse presentations of psoriasis. 8 On the contrary, our study noted slightly increased absolute delay to psoriasis diagnosis in non-SoC patients. This could be due to our practitioners’ greater familiarity with SoC presentations, given their practise in a tertiary care center in a highly diverse population in Ontario, Canada. Moreover, given certain groups of SoC patients present with more extensive and atypical psoriasis variants (eg, extensive BSA, pustulosis, erythroderma), primary care physicians may refer these patients more promptly to tertiary care centers in the setting of diagnostic uncertainty. Nonetheless, the difference in time to diagnosis was not statistically significant and was confounded by our small sample size and overlapping standard deviations, making its clinical significance uncertain.
Since all patients enrolled in the study were on systemic medication at some point, we did not use the classic BSA stratification (<3%, 3%-10%, and >10%) since we would not have patients meeting criteria for mild disease. Therefore, we divided the BSA to be under 10%, 10% to 49%, and over 50%. At initial presentation, the average BSA was comparable between SoC and non-SoC patients. However, non-SoC patients were more likely to have either limited (<10% BSA) or extensive (>50% BSA) involvement, while SoC patients typically fell into the 10% to 49% range. This pattern suggests greater variability in disease severity in our non-SoC cohort, while SoC patients generally presented with moderate involvement. Of note, this analysis included paradoxical psoriasis cases in both groups, which typically manifests with lower overall BSA and may partially influence the proportion of patients within the <10% BSA category. However, the prevalence of paradoxical psoriasis did not differ significantly between the groups. Prior studies have shown that although patients with SoC may have greater BSA involvement, psoriasis often exhibits less erythema, instead appearing as violaceous or hyperpigmented plaques, whereas in White patients, lesions typically present as pink-red.1,4 This difference can lead to underestimation of disease severity, with active psoriatic plaques being mistaken for postinflammatory hyperpigmentation. Our observation of fewer SoC with extensive (>50% BSA) involvement could be attributed to underdiagnosis, since erythema is less apparent and active plaques may be misinterpreted for postinflammatory hyperpigmentation.
IBD was more prevalent in White patients (P = .05), as was arthritis, at the time of psoriasis diagnosis. Psoriasis is known to be associated with IBD, which is more common in White populations. 9 However, there is limited research comparing IBD prevalence among pediatric patients with psoriasis across different skin type groups.
First-line treatment for psoriasis includes topical steroids, topical vitamin D analogues (alone or in combination), topical retinoids, topical calcineurin inhibitors, and topical phosphodiesterase inhibitors. 1 In our study, topical corticosteroids were the most prescribed treatment, used by 79.1% of the patients, with higher percentage in SOC patients (83.6%). These treatments are highly effective, with no significant differences in side-effect profiles in patients with SoC. 1 Betamethasone and calcipotriol were used at nearly identical rates across the groups. However, topical calcineurin inhibitors were more frequently used by non-SoC patients, possibly because stronger topical corticosteroids are preferred in SoC patients to mitigate the risk of postinflammatory hyperpigmentation with milder treatments. Although topical roflumilast is another option, it was not approved in Canada when these patients were being treated. Initial systemic treatment was more common among SoC patients, reflecting the severity of the disease in the first appointment.
Prior studies have shown that the usage of nonbiologic systemic treatments is higher in Black patients compared to White patients. 10 Methotrexate is one of the most frequently prescribed medications for moderate-to-severe psoriasis. 1 In our study, methotrexate was prescribed more frequently in SoC patients (67.3%), with an overall usage of 56.5%. Acitretin was the least used medication overall. Biologic therapies showed a trend toward higher usage in non-SoC patients (77.2% vs 63.2%), aligning with multiple studies that indicate that non-SoC patients are more likely to receive biologics. Factors such as patient education, insurance coverage, language accessibility, and experiences of bias or medical distrust may contribute to the lower use of biologics for SoC patients. Additionally, the under-reporting of psoriasis patients with SoC in clinical trials may affect knowledge of expected efficacy and safety in this population.4,10
Paradoxical psoriasis induced by TNF-α inhibitors represents a distinct, treatment-associated immune phenomenon due to innate, type I interferon mediated signaling. 11 In pediatrics, it classically involves the scalp. In our study, while the prevalence of paradoxical psoriasis between SoC and non-SoC patients was comparable, scalp involvement was significantly higher in White patients (P = .008), a finding consistent with prior research comparing the same groups. 12 This observation could be attributed to underreporting of scalp psoriasis, as subtle erythema might be less noticeable in darker skin tones, or maybe to a decreased tendency of paradoxical psoriasis in patients with darker skin tones. Given our modest and mixed sample size, these findings should be interpreted cautiously. Comparative data examining paradoxical psoriasis in SoC remains limited. A case report by Chao et al highlighted that TNF-α-induced psoriasis in patients with SoC is frequently underrecognized and misdiagnosed, underscoring importance of heightened clinical awareness. 13 Emerging in-vitro data suggest that healthy African American skin has intrinsically higher levels of proinflammatory signaling, including elevated TNF-α expression. 14 The clinical significance of these cytokine profile differences remains incompletely defined but may suggest differential responsiveness – and potentially varying susceptibility to paradoxical reactions – to TNF-α inhibitor therapy compared with non-SoC patients.
Finaly, the inability to distinguish psoriasis from paradoxical psoriasis within our dataset limits etiologic interpretation. Paradoxical psoriasis represents a biologically distinct entity from psoriasis vulgaris, and analyzing these entities collectively limits insight. Nonetheless, our study highlights the possibility of lower biologic use among SoC patients, which echoes prior studies in adults.4 -7,8,10 Larger studies incorporating detailed clinical data will be necessary to determine whether true differences in pediatric psoriasis (including paradoxical psoriasis) prevalence exist across racial groups.
Conclusion
Our study highlights key differences in psoriasis presentation, diagnosis, and treatment between patients with and without SoC at the Hospital for Sick Children, Toronto, Canada. Most of our findings align with existing literature, with the most statistically significant differences observed in the higher prevalence of scalp involvement in SoC patients and IBD among non-SoC patients. While TNF-α induced psoriasis patients were included in our cohort, the limited sample size and distinct pathogenesis of these conditions warrant cautious interpretation.
Regarding treatment, topical steroids were the most used therapy, with a slightly higher use in SoC patients. In addition, SoC patients were more frequently prescribed systemic nonbiologic treatments, whereas non-SoC individuals had higher rates of biologic use. This may be influenced by medical biases, underrepresentation in clinical trials, socioeconomic factors and potential differences in physician prescribing practices.
Due to the retrospective nature of this study, we were unable to assess Psoriasis area and severity index (PASI) scores, quality of life measures, or changes in BSA over time, as these were not routinely documented in follow-up clinical visits. Our study was limited by a small sample size, which restricts statistical significance and generalizability. Nonetheless, we hope it raises awareness about the importance of accurate diagnosis and timely treatment approaches for pediatric patients with SoC. Prospective studies using standardized assessment tools are needed to better characterize differences in presentation and treatment in this population.
Footnotes
Ethical Considerations
This study received ethical approval from the Research Ethics Board at the Hospital for Sick Children (approval #1000081028) on September 22, 2023. Patient data will not be shared with third parties.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: C.S. consulting: Eli Lily, Pfizer, Sanofi, Incyte; honoraria: Abbvie, Novartis, Pfizer, Sanofi, UCB; grants: Pfizer. All authors declared no conflicts of interests.