Background and importance Pharmacists are well positioned to improve clinical outcomes for patients by assisting with individualised patient in the outpatient setting. Given the difficulty of measuring the health outcome of disease-modifying therapies (DMTs) in patients with relapsing–remitting multiple sclerosis (RRMS), persistence to DMTs could be a good indirect measure.

Aim and objectives Our purpose was to analyse persistence and time to discontinuation (TD) of DMTs in patients with RRMS in a tertiary hospital.

Material and methods Retrospective, observational study in patients with RRMS who started DMTs with interferon-β (INF-β), glatiramer-acetate (GA), teriflunomide, dimethylfumarate (DF), fingolimod, natalizumab and alemtuzumab between 2016 and 2019. Persistence was calculated until April 2020 and defined as the length of time on the drug. Variables analysed: sex, age, Expanded Disability Status Scale (EDSS) at baseline, previous DMTs, TD, global persistence, persistence to DMT and causes of discontinuation.

Results 492 subjects were followed for a median time of 19.6 months, 69.3% women and median age 40 years. Median EDSS was 1 (0–6) in naïve patients and 2 (0–7) in pretreated patients. 250 patients were naïve (50.8%) and 242 pretreated (49.2%). 31.1% of patients had used one DMT before. DMTs prescribed were 113 DF, 108 teriflunomide, 87 IFN-β, 76 GA, 49 fingolimod, 34 natalizumab and 25 alemtuzumab. Median TD (months (range)) of DMTs was 14.1 (1–43) being longer in pretreated patients (16.8 (1–41)) than in naïve patients (13.9 (1–43)). Median TD per drug was natalizumab 27 (1–40), fingolimod 17 (3–32), IFN-β 16 (1–43), teriflunomide 15 (1–41), DF 11 (1–38) GA 10 (1–27) and alemtuzumab 9 (8–10). Global persistence was 66.2% and per drug: 92.0% alemtuzumab, 73.5% DF, 73.5% natalizumab, 68.4% AG, 67.3% fingolimod, 61.1% teriflunomide and 50.6% IFN-β. Main reasons for discontinuation were ‘intolerance’ 46.9% and inefficacy 39.8%. Discontinuation due to intolerance was INF-β 58.1%, GA 54.2%, DF 50%, teriflunomide 42.9% and fingolimod 37.5% and due to inefficacy fingolimod 50%, teriflunomide 50%, DF 43.3%, INF-β 34.9% and GA 29.2%. 88.9% atalizumab discontinuations were due to risk of progressive multifocal leukoencephalopathy (PML). The only reason for alemtuzumab discontinuation was inefficacy.

Conclusion and relevance Our cohort showed a high persistence rate. The main cause of discontinuation was ‘intolerance’. Patients with alemtuzumab, DF and natalizumab remained under treatment for longer. INF showed the lowest persistence. Low persistence may be related to intolerance.

Conflict of interest No conflict of interest