Long-term Outcomes and Prognosis in New-Onset Psoriasis

Abstract

Importance: Psoriasis is a heterogeneous disease. Improved understanding of prognosis and long-term outcomes in new-onset psoriasis may improve care.

Objective: To describe the clinical course of psoriasis and identify possible indicators of long-term outcomes.

Design, setting, and participants: The Stockholm Psoriasis Cohort was a noninterventional inception cohort study enrolling patients between 2001 and 2005. The present study was conducted from January 15, 2019, to February 5, 2021. At enrollment and 10 years, patients were examined by dermatologists and rheumatologists. Data from examinations were complemented by questionnaires, medical records, and registers. A total of 721 patients with recent-onset psoriasis (<12 months duration), 15 years or older were recruited using advertising and referrals from a broad range of health care settings.

Main outcomes and measures: Disease severity and psoriatic arthritis (PsA). Recursive partitioning and regression models were implemented to identify probable indicators of long-term outcomes.

Results: A total of 721 patients (median [interquartile range] age, 39 [27-55] years; 405 [56%] women), including 542 (75%) with plaque-onset and 174 (24%) with guttate-onset psoriasis, were enrolled. The median follow-up was 9.6 years (interquartile range, 8.8-10.4 years). The cumulative incidence of severe psoriasis at 12 years from enrollment was 21%. Among 509 patients examined clinically after 10 years, 77 of 389 patients (20%) with plaque onset and 56 of 116 (48%) with guttate onset had minimal disease activity without treatment, and 120 of 509 (24%) had PsA. Recursive partitioning identified strata with distinct risks for severe skin disease and PsA: the cumulative incidence of severe disease in patients with plaque phenotype, above-median disease activity, and scalp lesions was 52% (95% CI, 41%-64%), compared with 11% (95% CI, 8%-14%) in patients with below-median disease activity at inclusion; and 48 of 82 patients (59%) with peripheral enthesitis had PsA after 10 years compared with 37 of 304 patients (12%) without initial joint pain (P < .001). Smoking (hazard ratio, 1.70; 95% CI, 1.10-2.63) and activating genes in the interleukin-23 (IL-23) pathway (odds ratio, 1.55; 95% CI, 1.14-2.11) were also significantly associated with a severe disease course. Systemic therapy at or before enrollment was associated with a lower risk for severe disease at 10 years compared with later initiation of systemic therapy (odds ratio, 0.24; 95% CI, 0.06-0.90).

Conclusions and relevance: 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. Patients within those categories merit specialist referral and closer follow-up. The possibility of modifying the disease course with early systemic intervention should be tested.

Figure 1.. Disease Severity and Clinical Manifestations From Onset to 10 Years

Distribution of disease severity at enrollment and at 10 years in patients with plaque-onset (A) and guttate-onset (B) psoriasis. The transparent fields between the bars illustrate the flow of patients between disease severity categories at enrollment and the 10-year clinical examination.

Figure 2.. Examples of Severe and Benign Disease Course Along With Predictors of Disease Course

A patient with mild plaque psoriasis at onset (A) and severe disease at follow-up (B). A patient with severe guttate psoriasis at onset (C) and minimal disease activity (D) at follow-up.

Figure 3.. Outcomes for the Identified Groups for Severe Psoriasis, Minimal Disease Activity at 10 Years, and Psoriatic Arthritis

Cumulative incidence of severe disease beyond 10 years (A), proportion of patients with minimal disease activity at 10 years (B), and proportion of patients with psoriatic arthritis at 10 years. For panel A, group 1, the static Physician Global Assessment Index (s-PGA) was ≤3; for group 2, s-PGA was >3 in guttate onset or s-PGA was >3 in nonguutate onset without scalp lesions; for group 3, s-PGA was >3 in nonguttate onset with scalp lesions. For panel B, group 1 was the guttate onset; group 2 was nonguttate onset without scalp lesions; and group 3 was nonguttate onset with scalp lesions. For panel C, group 1 was no joint pain; group 2 was joint pain but no enthesitis; and group 3 was enthesitis. eTable 5 in the Supplement presents further details.

Figure 4.. Proportion of Patients With Severe Psoriasis at the 10-Year Clinical Examination Stratified by Time to Systemic Initiation

Error bars indicate exact binomial 95% confidence limits.