Treatment Switching and Drug Survival of Biologic Therapies in Psoriasis: A Real-World Italian Study Across Biologic Classes

Background/Objectives: Psoriasis is a chronic inflammatory skin disease leading to substantial psycho-physical and social burden and reduced quality of life. Biologic agents have transformed its therapeutic landscape. This real-world Italian study described the pattern of treatment with biologic drugs in patients with psoriasis. Methods: A retrospective observational study was conducted using administrative databases from Italian Local Health Units, covering nearly 12 million individuals. The study included adults with psoriasis identified from January 2015 to March 2025 by hospitalization, co-payment exemption code, or topical anti-psoriatic prescriptions. Patients initiating a biologic drug (anti-TNF alpha, anti-IL12/23, anti-IL17, and anti-IL23) were selected and further analyzed in terms of treatment switching, drug survival, and healthcare resource utilization and related costs within the first year after biologic initiation, and compared. Results: A total of 10,270 biologic-na & iuml;ve adult patients was included in the analysis (anti-TNF alpha N = 5078; anti-IL12/23 N = 767; anti-IL17 N = 2574; anti-IL23 N = 1851). Most patients (95.0%) starting an anti-IL23 agent did not switch. Compared with anti-TNF alpha, initiating an anti-IL23 inhibitor was associated with a significant reduced risk of switching (HR = 0.186; 95%CI: 0.144-0.240; p < 0.001). According to the cost analysis stratified by switching status, remaining on the index biologic was associated with a lower economic burden. Although differences between switchers vs. non-switchers among anti-IL23 users did not reach statistical significance (& euro;12,052 vs. & euro;11,406, respectively, p = 0.132), data support the economic advantage associated with greater treatment stability. Conclusions: Anti-IL23 agents showed effective, durable first-line use with potential long-term clinical and economic benefits in moderate-to-severe psoriasis.