Plaque phenotype, IL-23 at baseline may predict downstream severe psoriasis

Individuals with psoriasis who had plaque phenotype and interleukin-23 involvement at baseline were more likely to develop severe skin disease at 10 years, according to a study.

Due to the heterogeneity of psoriasis, improved understanding of prognostic factors and long-term outcomes in new-onset disease may be beneficial to patient care, according to Axel Svedbom, MsC, of the division of dermatology and venereology in the department of medicine at the Karolinska Institutet, Stockholm, and colleagues.

The researchers used data from the Stockholm Psoriasis Cohort to describe the clinical course of psoriasis and potential indicators of long-term outcomes in a cohort of 721 patients with recent-onset disease.

Eligible participants had psoriasis for less than 12 months and were aged 15 years or older. While the initial cohort was enrolled between 2001 and 2005, the current study was conducted between Jan. 15, 2019, and Feb. 5, 2021.

Participants underwent examination by a dermatologist and a rheumatologist at enrollment and at 10 years. In addition, participants completed questionnaires, while clinicians reviewed their medical records and registers.

Disease severity and incidence of psoriatic arthritis (PsA) served as the primary endpoints.

The cohort had a median age of 39 years and was 56% women. Plaque-onset psoriasis was reported in 75% of patients, while 24% had guttate-onset disease.

Follow-up lasted a median of 9.6 years.

Results showed a cumulative incidence of severe psoriasis of 21%. There were 509 patients who underwent clinical examination at 10 years. Of that group, among 389 patients with plaque-onset psoriasis, 20% had minimal disease activity without treatment. For 116 patients in the guttate-onset group, 48% had minimal disease activity with no treatment. Another 24% of the 509 patients with complete follow-up assessment went on to develop PsA.

Looking at risks for skin disease severity, 52% (95% CI, 41%-64%) of individuals with plaque phenotype, above-median disease activity and scalp lesions at onset were more likely to develop severe disease. However, severe disease developed in just 11% (95% CI, 8%-14%) of patients with disease activity below the median at inclusion.

Regarding PsA risk, 59% of patients with peripheral enthesitis reached this outcome, while just 12% of patients with no joint pain at inclusion developed PsA (P < .001).

Other prognostic factors for severe disease course included smoking (HR = 1.70; 95% CI, 1.10-2.63) and activating genes along the IL-23 pathway (OR = 1.55; 95% CI, 1.14-2.11).

Patients who were treated with systemic therapy at or before enrollment were less likely to develop severe disease at 10 years compared with those who initiated systemic therapy later (OR = 0.24; 95% CI, 0.06-0.90).

“The findings of this cohort study suggest that combinations of clinical characteristics at onset and activating genes in the IL-23 pathway are significantly associated with the clinical course of psoriasis, whereas joint pain and peripheral enthesitis may indicate the probability of PsA,” the researchers wrote. “Patients within those categories merit specialist referral and closer follow-up.”