Association Between Initial Corticosteroid Regimen and Treatment Response Time in Acetylcholine Receptor Antibody–Positive Myasthenia Gravis

Abstract

Background: Corticosteroids remain the cornerstone in the management of myasthenia gravis (MG). Initiation of corticosteroid treatment at a high dose and subsequently decreasing the dose or gradual escalation from a low dose is recommended. We aimed to investigate the association between the initial corticosteroid regimen and treatment response.

Methods: A retrospective study was conducted on 234 acetylcholine receptor (AChR) antibody (Ab)–positive MG patients who visited our institution between January 2010 and February 2023. Patients were grouped based on prednisolone dosages received: initial high (IH, ≥50 mg/day) or initial low (IL, ≤20 mg/day). Time to initial improvement and the achievement of minimal manifestation (MM) status were the main outcomes.

Results: Of the 234 patients, 135 were classified as IH and 99 as IL group. The IH group demonstrated a faster onset of improvement compared with the IL group (20.0 [16.0–29.0] vs. 40.0 [27.0–84.0] days), with the IH group being a significant prognostic factor for initial improvement (HR, 2.44; 95% CI, 1.76–3.39). However, the IH group had a higher incidence of steroid-induced exacerbation (51.9% vs. 2.0%, p < 0.001). No significant difference between the IH and IL groups was found in terms of the proportion of patients achieving MM or the time to achieve MM within the first year after treatment initiation.

Conclusion: While an initial high dose of corticosteroid treatment accelerated the onset of therapeutic responses in patients with AChR Ab–positive MG, it was associated with a higher cumulative steroid dose and an increased risk of steroid-induced exacerbations.