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.