Individualising Guselkumab Maintenance in Psoriatic Disease: Clinical Profiles Associated with Dosing-Interval Modification in a Multicentre Cohort

Background/Objectives: Individualising guselkumab maintenance is increasingly considered in clinical practice, but the characteristics associated with clinicians’ decisions to modify dosing intervals remain poorly defined. We investigated the clinical profiles of patients undergoing interval extension or reduction and assessed drug survival after interval reduction in patients with psoriatic arthritis (PsA). Methods: This retrospective study included patients receiving guselkumab for psoriasis across eight Italian centres. Patients undergoing interval extension beyond every eight weeks (q8w; n = 39) were compared with those without interval extension (n = 951). Separately, patients with PsA undergoing interval reduction from q8w to every four weeks (q4w; n = 39) were compared with patients with PsA maintained on q8w (n = 184). Between-group comparisons were exploratory and unadjusted. Post-interval reduction drug survival was estimated using the Kaplan–Meier method. Results: Patients undergoing extension had less frequent palmoplantar involvement (2.6% versus 14.7%; p = 0.033), nail involvement (0% versus 13.6%; p = 0.014), and PsA (7.7% versus 23.1%; p = 0.023), and more frequent previous anti-IL-12/23 treatment (35.9% versus 18.2%; p = 0.006). Within the PsA population, interval reduction was associated with younger age (56.9 versus 62.8 years; p = 0.023) and obesity (41.0% versus 23.4%; p = 0.023). Five patients subsequently returned to standard q8w dosing following clinical improvement. All 39 patients undergoing interval reduction were included in the survival analysis, with six guselkumab discontinuations. Estimated drug survival was 97.1% at 52 weeks (95% CI 81.4–99.6%) and 84.2% at 104 weeks (95% CI 62.7–93.9%). Conclusions: Guselkumab interval modification was associated with distinct clinical profiles, suggesting that disease phenotype, joint involvement, and treatment history contribute to individualised maintenance decisions. These findings describe clinical selection in routine practice and support prospective evaluation of patient selection criteria and long-term outcomes.