Analysis of the prevalence of ankylosing spondylitis and treatment patterns and drug utilization among affected patients: an Italian real-world study

Objectives To evaluate the prevalence of ankylosing spondylitis (AS) and associated treatment patterns and drug utilization in real-world clinical practice in Italy. Methods This observational study used data from administrative databases of selected Italian entities and included patients with AS diagnosis identified by ICD-9-CM and/or exemption codes. Patients without biologic disease-modifying antirheumatic drug (bDMARD) prescriptions prior to inclusion were defined bio-naive. A cross-sectional analysis identified treatment patterns from 2016 to 2018. A longitudinal analysis investigated bDMARD utilization (persistence, switch, discontinuing treatment) among bio-naive patients, with 2014 and 2017 as inclusion periods. Follow-up extended from first bDMARD prescription (index date) to end of data availability. Results The prevalence of AS was 75.5 per 100,000 (88.3 per 100,000 in adults) in 2018. In total, 5,942 AS patients were identified in 2016, 6,554 in 2017, and 7,146 in 2018. bDMARDs were prescribed to 21.4% (2016), 22.0% (2017), and 16.9% (2018) of the patients. Among the 349 patients included in 2014, 9.5% switched therapies, 13.8% discontinued treatment. In 2017, 12.2% of the 262 patients included switched therapies, 27.1% discontinued treatment. Conclusions This study provided an up-to-date prevalence of AS diagnosis in Italy. Bio-naive patients showed an increasing tendency toward switch of therapy and discontinuation.