Supplementary Material for: The impact of mesalazine pill burden on compliance in inflammatory bowel disease patients

Background: There are a limited number of studies that have investigated mesalazine persistence and adherence using administrative/pharmacy claims data that may approximate real-world clinical practice data, therefore the aim of this study was to compare the adherence to oral mesalazine between different groups of inflammatory bowel disease (IBD) patients in relation to the tablet strength (number of pills per day) dispensed in retail pharmacy. Methods: This was a retrospective cohort study in French patients using the IQVIA Longitudinal Prescription Data; a patient database based on retail pharmacy claims. Results: Of the 21,669, patients with a pharmacy claim for oral mesalazine initiated for IBD between June 2020 and April 2022, after exclusion criteria was applied 12,122 IBD treatment-naïve patients initiating mesalazine treatment were included. A high strength (HS) (1600 mg), medium strength (MS) (800-1000 mg) and low strength (LS) (400-500 mg) mesalazine tablet was dispensed to 1216, 8631, and 2275 patients, respectively. Persistence to medication at 6 months of follow-up was 44.6%, 35.4%, and 25.3% in the HS, MS and LS group, respectively. After 1 year of follow-up, it was 22.0%, 17.1% and 11.5% in the HS, MS and LS group, respectively. Patient adherence to mesalazine tablets was 41.3% patients in the HS group 35.5% patients in the MS group and 28.0% patients in the LS group (p<0.001). Conclusion: The results showed a consistent higher adherence with the decrease of pill burden. High strength tablets were significantly associated with higher persistence and higher adherence to medication compared to the medium and low strength tablet group.