Research Summary

Psoriatic Arthritis Risk Predictors Identified at Psoriasis Onset

Edited by:
Ashton L. Stahl

Key Highlights

  • Among 628 participants with new-onset psoriasis, 83 (13%) had concomitant psoriatic arthritis.
  • A biomarker-based model identified patient groups with psoriatic arthritis risks ranging from 1% to 62%.
  • The models achieved optimism-adjusted areas under the curve of 0.76 to 0.84.
  • Pain, HLA-B27, and systemic inflammation were the strongest predictors of future psoriatic arthritis.

Predictors of psoriatic arthritis were detectable at the onset of psoriasis in a Swedish inception cohort, according to findings published in The Lancet Rheumatology. The researchers developed models to support rheumatology referrals and to identify patients with subclinical disease at increased risk of developing clinical psoriatic arthritis.

The analysis used data from the Stockholm Psoriasis Cohort, which enrolled patients within 1 year of their first psoriasis lesion on non-hairy skin between January 5, 2001, and December 14, 2005. Predictors were collected at enrollment. Researchers developed 2 referral models, with and without biomarkers, and 2 prognostic models for subclinical psoriatic arthritis, using 3-year and 15-year prediction horizons.

Recursive partitioning and penalized regression were used to construct the models. Performance was evaluated according to discrimination, calibration, and net benefit across clinically reasonable risk thresholds informed by a clinician survey. People with lived experience of psoriasis participated in the study’s design.

Study Findings

The analysis included 628 participants who reported no psoriatic arthritis at enrollment. Of these, 347 (55%) were female, and 281 (45%) were male; the median age was 40.9 years (IQR, 30.1-56.0 years). Despite reporting no psoriatic arthritis, 83 participants (13%) had concomitant disease.

Recursive partitioning with laboratory biomarkers separated participants into 4 risk groups based on arthralgia, fatigue, psoriasis phenotype, high-sensitivity C-reactive protein, and psoriasis disease activity. The estimated risks of concomitant psoriatic arthritis across these groups ranged from 1% to 62%.

The 15-year penalized regression model incorporated 9 variables, while the 3-year model used a subset of those predictors. All models demonstrated good discrimination, with optimism-adjusted areas under the curve ranging from 0.76 to 0.84. The models showed reasonable calibration and provided positive net benefit for referral and monitoring decisions at thresholds derived from the clinician survey. However, they appeared to offer limited value for preventive treatment decisions.

All models exhibited instability, particularly the prognostic models. Pain, HLA-B27, and systemic inflammation emerged as the strongest predictors of future psoriatic arthritis.

Clinical Implications

According to the study authors, the findings suggest that predictors of psoriatic arthritis are already present at the onset of psoriasis. The models could therefore, support decisions regarding rheumatology referral and patient monitoring, but the authors emphasized that external validation is required before clinical implementation.

Expert Commentary

“Predictors of psoriatic arthritis are already present at psoriasis onset. The models developed here could support clinical decision making, but they require external validation before implementation,” the researchers concluded.

Reference

Svedbom A, Mallbris L, Zabotti A, et al. Predicting psoriatic arthritis in new-onset psoriasis: development of multivariable prediction models from an inception cohort study. Lancet Rheumatol. Published online June 30, 2026. doi:10.1016/S2665-9913(26)00115-3