The following is a summary of “Association between biological immunotherapy for psoriasis and time to incident inflammatory arthritis: a retrospective cohort study,” published in the April 2023 issue of Rheumatology by Singla et al.

Patients with psoriasis have found targeted biological immunotherapies to be very helpful in managing their skin condition. However, it is not known whether this treatment modifies the risk of developing inflammatory arthritis. This research evaluated how long patients were taking biological treatments for psoriasis to develop inflammatory arthritis. The electronic health records database of the US-based TriNetX network was the source of information for this retrospective cohort study. Patients were considered if they were adults (aged 18 years) and had been recently prescribed a biologic (inhibitors of tumor necrosis factor [TNF], interleukin [IL]-17, IL-23, or IL-12/23, first prescribed on or after the date of receiving a first psoriasis diagnosis code, >30 days apart; International Classification of Diseases [ICD] codes). 

After beginning biological therapy, the Kaplan-Meier estimate was used to create a survival curve depicting the time until the first incidence of inflammatory arthritis, as defined by the presence of a diagnostic code for psoriatic arthritis or another kind of inflammatory arthritis.

 Researchers used weighted Cox proportional hazards regression, using anti-TNF exposure as the reference, to estimate the time-dependent risk of inflammatory arthritis after controlling for demographic and clinical covariables. In addition, incident instances of psoriasis, longer exclusion periods for prevalent cases of inflammatory arthritis, treatment switching, and stricter illness and outcome definitions were also assessed through sensitivity analyses. The total number of patients diagnosed with psoriasis between 2014 and 2022 was 15,501 (mean age 50.2 years [SD 15.0]; gender split of 8,399 (54.2%) women and 7,102 (44.8%) men; race split of 11,175 (72.1%) Whites). Inflammatory arthritis affected 976 (6.3%) of the 15,501 patients, for a total incidence of 2,6 per 100,000 people-years. 

The risk of developing inflammatory arthritis was considerably reduced in patients prescribed IL-12/23 inhibitors (adjusted HR 0.58, 95% CI 0.43-0.76) or IL-23 inhibitors (adjusted HR 0.41, 0.17-0.95) compared to individuals prescribed TNF inhibitors in multivariable regression analysis. When comparing IL-17 and TNF inhibitors, researchers found no statistically significant difference (0.86, 0.54-1.38). All sensitivity analyses maintained the same findings for IL-12/23 inhibitors. In three of six sensitivity analyses, results for IL-23 inhibitors were stable even after omitting patients who developed arthritis within 3 or 6 months of their first biologic prescription and using a higher diagnostic threshold for incident arthritis. Treatment with IL-12/23 inhibitors or IL-23 inhibitors was linked with a decreased risk of progression to inflammatory arthritis compared with TNF inhibitors in this large cohort trial of individuals with psoriasis. These results need to be confirmed by prospective observational cohorts with markers of disease activity and by a pooled analysis of prior randomized trials.