Safety outcomes of disease-modifying therapies for relapsing-remitting multiple sclerosis: A network meta-analysis

Background: Randomised clinical trials (RCTs) and observational studies have reported adverse events that preclude the use of disease-modifying therapies (DMTs) in relapsing-remitting multiple sclerosis (RRMS) in the long term or in specific populations, however, little is known about the relationship between the use of DMTs and frequency of undesirable events. We aimed to conduct a systematic review and network meta-analyses (NMAs) of RCTs and observational studies to synthesise the evidence on the safety of all available DMTs for patients with RRMS. Methods: PubMed, Scopus and a manual search were performed. Bayesian NMAs of safety outcomes reported in RCTs and observational studies assessing DMTs as monotherapies were conducted. Results: Forty-seven studies were included in the systematic review. Considering all studies, 368 and 149 different safety outcomes were reported for at least one study and two studies, respectively. Considering clinical trials, 22 NMAs were conducted for 16 outcomes. Regarding geometry metrics, the median number of studies, DMTs, common comparator, strong edge, and patients were 5 (IQR 5-9), 5 (IQR 4-8), 44%, 33%, and 3998 (IQR 3380-6761). In summary, most comparisons showed similar risk of safety events for DMTs and placebo for all outcomes. Considering cohort studies, only three meta-analyses were conducted. Conclusion: Safety outcomes are poorly reported in primary studies of DMTs in RRMS, precluding the conduction of robust meta-analyses. Therefore, the current available data on safety of these drugs is not contributing to regulatory and clinical decision making, with adverse event reports underbalanced compared to efficacy outcomes.