Real world use of biological drugs in patients with psoriasis/psoriatic arthritis: a retrospective, population-based study from Southern Italy in the years 2010-2014

BACKGROUND: Biological drugs, such as infliximab, etanercept, adalimumab, ustekinumab, golimumab and certolizumab are third-line therapy for psoriasis (PsO) and psoriatic arthritis (PsA), but they may be used at earlier stage in severe forms. This study investigated the pattern of use and costs of biological drugs for PsO/PsA in a large population from Southern Italy during the years 2010-2014. METHODS: This was a retrospective, population-based, drug-utilization study, using healthcare administrative databases of the ASL (Local Health Unit) and two hospitals of Messina Province (Sicily) in the years 2010-2014. Incident users of adalimumab, ustekinumab, infliximab, etanercept and golimumab for PsO/PsA were characterized. Yearly prevalence of use and costs, as well as time to treatment discontinuation and switch were assessed. RESULTS: During the study period, 517 patients received at least one study drugs prescription for PsO/PsA and 304 (58.8%) were incident users, mostly treated with adalimumab (33.6%). Incident users were mostly males (59.8%), with a median age of 49 years. The prevalence of biological drugs users in PsO/PsA increased from 4.3 to 6.9 per 10,000 inhabitants from 2011 to 2014. Pharmaceutical expenditure of the study drugs almost doubled (from 2.6 to 4.7 million euros over 5 years of observation). During the first year of treatment, discontinuation occurred in 31.8% of incident users and switch was not infrequent (7.4%). CONCLUSIONS: Prevalence of use and costs of biological drugs for PsO/PsA substantially increased in recent years in a large population of Southern Italy. Larger uptake of lowest cost biological drugs, and biosimilars whenever available, may help access to the most innovative drugs.