P115 Differential risk of incident psoriatic arthritis across immunomodulator classes used for psoriasis: a prospective cohort study

Abstract

Psoriatic arthritis (PsA) affects 20–30% of individuals with psoriasis. Whether systemic immunomodulators for psoriasis differentially influence risk of new-onset PsA remains unclear. The aim of this study was to compare incident PsA risk across psoriasis therapies. Data from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR) were analysed. Participants were aged ≥ 16 years, had no PsA diagnosis at enrolment and received methotrexate (MTX) or biologic monotherapy for plaque psoriasis. Time was counted from treatment initiation until PsA onset, treatment discontinuation or last follow-up. Hazard ratios (HR) with 95% confidence intervals (CIs) for incident PsA by treatment class were estimated using ­propensity-score-weighted flexible parametric survival models. Primary and secondary models included biologic-naive patients only, defined as first therapy with no prior biologics, and all treatment lines. The study included 22 661 treatment exposures among 15 872 participants, with 86 909 person-years of exposure time. The breakdown by drug class was MTX 15%, tumour necrosis factor inhibitors (TNFis) 37%, interleukin (IL)-12/23 inhibitors 27%, IL-17 inhibitors 13% and IL-23 inhibitors 8%. There were 1120 incident PsA events. In biologic-naive participants, relative to TNFi, PsA risk was lower with IL-12/23 inhibitors (HR 0.75, 95% CI 0.58–0.98) and IL-23 inhibitors (0.42, 0.21–0.82) but not with IL-17 inhibitors (0.93, 0.67–1.28). After including all treatment lines, the findings were similar to the biologic-naive analysis. For exposures starting before the availability of IL-23 inhibitors (all treatment lines), IL-12/23 inhibitors were associated with lower risk than TNFis (HR 0.57, 95% CI 0.45–0.71). Relative to MTX, risk was lower with grouped biologics (HR 0.82, 95% CI 0.71–0.95), TNFis (0.82, 0.69–0.96) or IL-23 inhibitors (0.50, 0.37–0.68). The effect of TNFis, but not IL-23 inhibitors, varied by average Psoriasis Area and Severity Index during exposure. Risk of PsA was lower with biologics than with MTX. While IL-23 axis inhibition appeared to be associated with a lower risk of PsA than TNFis, prescribing bias cannot be excluded. Further research is needed to establish whether these findings reflect true differences in incident PsA risk, or methodological limitations of the cohort design.