Objective was to describe treatment patterns and evaluate adherence and persistence of bDMARDs among patients diagnosed with AS in Japan using hospital-based claims database. Patients aged ≥ 10 years diagnosed with AS between April 1, 2009 and July 31, 2017 with ≥ 12 months of data following the first observed AS diagnosis (index date) were selected for analysis. Utilization of AS-related treatments was described. Treatment adherence and persistence were assessed for index bDMARD. Adherence was evaluated by computing medication possession ratio (MPR). Patients were considered adherent if MPR was ≥ 0.8. Discontinuation of the index bDMARD was defined as lack of a refill within 90 days of exhausting the index bDMARD days' supply from the prior prescription. Persistence rate was calculated using the Kaplan-Meier method. Among 417 eligible patients, mean (SD) age at the index date was 60.6 (16.4) years; 60.2% were male. The average (SD) follow-up time was 33.0 (18.7) months with a mean (SD) Charlson Comorbidity Index score of 1.3 (1.7). During the first 12 months after the index date, 79.6% of patients received NSAIDs, 39.3% received corticosteroids, 33.8% received non-bDMARDs, and 25.2% of patients received bDMARDs. The mean (SD) time from the index date to bDMARD initiation was 59.3 (81.4) days. Adalimumab (14.2%) and infliximab (12.2%) were the most common bDMARDs prescribed within 12 months. Of the patients who initiated a bDMARD, 71.1% (SE, 4.3%) of patients were persistent at 12 months. The mean (SD) MPR for first observed bDMARD at 12 months (n=101) was 0.9 (0.1) and 73.0% of patients were adherent on bDMARD. Using hospital claims we observed that nearly one-quarter of patients initiated treatment with a bDMARD within 12 months of the first observed AS diagnosis. The average time to initiation of bDMARD was approximately 2 months; adalimumab and infliximab were the most common prescribed bDMARDs, and 71% of patients were persistent on index bDMARD at 12 months.
