Effects of disease-modifying treatments discontinuation in patients with relapsing-remitting multiple sclerosis: A 5 year prospective cohort study

Background: One of the most challenging issues in patients with multiple sclerosis is the discontinuation of Disease-Modifying Treatments (DMTs) and subsequent complications. Objective: We aimed to investigate the extent of adherence to DMTs in naive multiple sclerosis patients, outcomes of non-adherence to treatments, and the risk factors that lead to drug discontinuation. Materials and Methods: In this prospective cohort study, 288 naive cases of Relapsing-Remitting Multiple Sclerosis (RRMS) with the age of 18 years and older were included. Their baseline EDSS (Expanded Disability Status Scale) amounts were < 2, and they were followed from 2015 for the duration of 5 years. Patients underwent clinical examination every 3 months and MRI once a year and all information was recorded. Moreover, patients that experienced pregnancy during the study period, were excluded from the main study population and evaluated separately. At the end of the 5-year period, DMT adherence rate, factors affecting treatment continuity, and the effect of treatment continuity on developed disabilities based on the EDSS were measured and analyzed by statistical software SPSS-26, CMA-3.7, and STATA-17. Results: The mean age of patients was 30.01 +/- 7.21 years. 12.2% of them were male and 87.8% were female. The treatment adherence rate was 82.5%, and tiredness of treatment prolongation (42.5%) was the most important reason for non-adherence to treatment. Additionally, There was a significant relationship between treatment adherence rate and the higher education level (P value = 0.016), being married (P value = 0.006), and the type of DMTs (Glatiramer Acetate (Adjusted OR = 7.7), Rituximab (Adjusted OR = 3.83), and Fingolimod (Adjusted OR = 3.81) had the highest adherence rates.). However, treatment adherence had no significant relationship with age, gender, employment, and patients' familial histories. The mean EDSS of patients with and without drug continuity after 5 years were 0.92 +/- 1.09 & 1.76 +/- 1.17, respectively, which showed a significant difference (P value < 0.001) in developed disabilities. Furthermore, the survival estimate of patients with drug adherence was higher than the other group. Conclusion: Approximately one in five patients with RRMS does not have treatment adherence during the first 5 years of treatment. Type of DMT, level of education, and marital status are factors that affect treatment adherence. Poor treatment adherence is associated with EDSS progression in multiple sclerosis patients.