Adherence to colchicine prophylaxis among patients with familial Mediterranean fever treated with interleukin-1 inhibitors

Objective: Interleukin-1 (IL-1) inhibitors are approved for treating familial Mediterranean fever (FMF) that is resistant to colchicine. However, continued concomitant treatment with colchicine is imperative, as it is the only drug proven to prevent secondary amyloidosis. We aimed to compare the adherence to colchicine between patients with colchicine-resistant FMF (crFMF) who were treated with IL-1 inhibitors and patients with colchicine-sensitive FMF (csFMF) who were treated only with colchicine. Methods: The databases of Maccabi Health Services, a 2.6-million-member state-mandated health provider in Israel were searched for patients with FMF diagnosis. The medication possession ratio (MPR), calculated from the day of the first colchicine purchase (index date) until the last colchicine purchase was the main outcome measure. Patients with crFMF were matched in a 1:4 ratio to patients with csFMF. Results: The final cohort included 4526 patients. Of them, 108 (2.4%) were with crFMF, and were matched to 432 with csFMF. The total mean MPR in each of the matched groups was similar (78.9 ± 41.4 and 82.5 ± 80.6, respectively, P = 0.5). Statistically significant differences in MPR were not found between the groups according to age or duration of colchicine use. However, adherence to colchicine was insufficient (MPR<80%) among more than 50% of the patients in both groups. Conclusion: In contrast to initial concerns, adherence to colchicine was similar between patients with crFMF and csFMF. However, in both groups, adherence to colchicine was poor. Education of both caregivers and patients is essential to increase adherence.