Are Patients with Psoriasis and Psoriatic Arthritis Undertreated? A Population-Based Study from Southern Italy

This study aimed to explore the pattern of use of different treatment lines in psoriasis (PsO) and psoriatic arthritis (PsA) patients from Southern Italy. A retrospective cohort study was performed during the years 2010-2018 using data from the Caserta Local Health Unit (LHU) claims database. All of the PsO or PsA patients were identified. The proportion of PsO/PsA patients untreated or treated with ≥1 drug classes (i.e., non-disease-modifying antirheumatic drugs (non-DMARDs), conventional synthetic DMARDs (csDMARDs), biological drugs (bDMARDs) or targeted synthetic small molecules (tsDMARDs)) was calculated in the years 2016-2018. Among the bDMARD users, the median times from the first registered PsO/PsA diagnosis/from the first csDMARD to the first bDMARD were calculated. Overall, 10,296 (1.1%) and 1724 (0.2%) PsO and PsA patients were identified. More than half of the PsO patients (N = 5301; 51.6%) and 15% of the PsA patients (N = 251) were not treated with any drug. A very low proportion of PsO patients (N = 121; 1.2%) received csDMARDs/bDMARDs dispensing. Instead, 538 (32.2%) PsA patients were treated with bDMARDs. The median times from the first diagnosis to the first bDMARD dispensing were 54.0 (Q1-Q3: 30.5-72.2) and 13.3 (Q1-Q3: 3.1-43.9) months in the PsO and PsA patients, respectively. The median time from the first csDMARD to the first bDMARD dispensing was shorter in the PsO [9.2 months (Q1-Q3: 5.5-30.0)] than in the PsA [14.5 months (Q1-Q3: 8.6-33.5)] patients. A potential undertreatment of PsO (much less for PsA) in an LHU from Southern Italy, with a particularly low use of more recently marketed drugs, such as biological ones, was shown.