Determinants of botulinum toxin discontinuation in multiple sclerosis: a retrospective study

The purpose of the present study was to investigate the long-term persistence to treatment with botulinum toxin type A (BoNT-A) for multiple sclerosis (MS)-related spasticity and the determinants of BoNT-A discontinuation in daily clinical setting. We retrospectively collected data of patients who started BoNT-A injections and underwent regular follow-up visits. Determinants of BoNT-A discontinuation were explored in a time-to-event Cox regression analysis which included as independent variables a large set of demographic and clinical characteristics. A total of 185 patients started BoNT-A injections from 2002 to 2014 and were followed up to September 2016. Of them, data on 121 were considered in our analysis. At follow-up, 53 (44%) patients were still on treatment and 68 (56%) patients discontinued BoNT-A after a median time of 1.2 years [interval 6 months to 7.4 years]. The reasons for discontinuation were loss of efficacy (n = 45), logistic problems or barriers to reach the structure (n = 16), and adverse events (n = 7). The absence of caregiver (hazard ratio = 1.69, p = 0.03) and lack of regular rehabilitation (hazard ratio = 1.78, p = 0.02) were two independent predictors for BoNT-A discontinuation. Our study confirms the beneficial effect of combining BoNT-A injections with rehabilitation and highlights the crucial role of caregivers for achieving better long-term outcomes in people with MS suffering from spasticity.