The role of autoantibody levels as biomarkers in the management of patients with myasthenia gravis: a systematic review and expert appraisal.

BACKGROUND: Although myasthenia gravis (MG) is recognised as an IgG autoantibody-mediated disease, the relationship between autoantibody levels and disease activity in MG is unclear. We sought to evaluate this landscape through systematically assessing the evidence, testing the impact of pre-defined variables on any relationship and augmenting with expert opinion. METHODS: In October 2020, a forum of leading clinicians and researchers in neurology from across Europe (Expert Forum Rare Autoantibodies in Neurology in Myasthenia Gravis [EFRAN MG]) participated in a series of virtual meetings which took place alongside the conduct of a systematic literature review (SLR). RESULTS: Forty-two studies were identified meeting inclusion criteria. Of these, 10 reported some correlation between a patient's autoantibody level and disease severity. Generally, decreased autoantibody levels (AChR, MuSK and titin) were positively and significantly correlated with improvements in disease severity (QMG score, MGC score, MG-ADL score, MGFA classification). Given the limited evidence, testing the impact of pre-defined variables was not feasible. CONCLUSIONS: This first SLR to assess whether a correlation exists between autoantibody levels and disease activity in patients with MG has indicated a potential positive correlation, which could have clinical implications in guiding treatment decisions. However, in light of the limited and variable evidence, we cannot currently recommend routine clinical use of autoantibody level testing in this context. For now, patient's characteristics, clinical disease course and laboratory data (e.g., autoantibody status, thymus histology) should inform management, alongside patient reported outcomes. We highlight the need for future studies to more definitively conclude on this relationship.