Adults who had ≥1 inpatient or ≥2 outpatient claims (≥30 days apart) with MG diagnosis from 2017-2022, with ≥1 diagnosis provided by neurologist, and ≥12 months pre- and post-index (i.e., initial MG diagnosis) continuous enrollment were selected from the MarketScan^® commercial and Medicare Supplemental databases. Patients with MG diagnosis during 12 months pre-index were excluded. MG exacerbation was defined as having a medical claim associated with MG acute exacerbation, the use of immunoglobulin or plasma exchange or MG-related hospitalization. MG crisis was defined as MG-related hospitalization associated with respiratory failure and endotracheal intubation/ventilation. Monthly all-cause healthcare costs before and after MG diagnosis were analyzed using restricted maximum likelihood controlling for age, gender, Charlson comorbidity index, and payer type.

A total of 891 newly diagnosed MG patients were identified [mean (±SD) age: 55.7 (±15.3) years; female: 52.7%; mean (±SD) Charlson comorbidity index: 1.2 (±1.6)]. All-cause costs increased by $1,163 per patient per month after MG diagnosis (P<0.0001) compared to pre-diagnosis. MG exacerbation and crisis further increased all-cause costs in the month that the event occurred by $13,283 and $81,840 per patient, respectively (both P<0.0001). On average, monthly all-cause costs continued to increase by $17 and $147 per patient for each additional month following MG exacerbation (P=0.011) and crisis (P<0.0001), respectively.