OBJECTIVES: Intravenous immunoglobulin (IVIg) is used in the treatment of patients with generalized myasthenia gravis (gMG), a rare autoimmune disorder. The objective of this study was to assess real-world IVIg usage patterns and its implications on costs over 1 year post-initiation in adults with gMG in the United States.

METHODS: Adults (≥18 years) with gMG who initiated IVIg were identified from Symphony Health’s Integrated Dataverse (IDV)^®, January 1, 2014 – December 31, 2019, unprojected de-identified patient prescription and medical claims, January 2020 dataset. IVIg courses were defined as ≥1 IVIg claims filed consecutively with ≤5 days between claims. Patients who received ≥6 IVIg courses over 1 year post-initiation were defined as chronic users (CU), while those who received ≤5 were defined as intermittent users (IU). Mean all-cause medical costs included medical service and pharmacy costs, and were assessed over 1 year post-IVIg initiation.

RESULTS: Among 1627 patients with gMG who initiated IVIg during the study period, 928 (57.0%) were IU and 699 (43.0%) were CU during the first year. 41.9% (389/928) of IU and 46.6% (326/699) of CU had at least one exacerbation or crisis event (E/C) during the year preceding IVIg initiation. Mean annual medical costs per patient for CU were 2.2- to 2.9-fold greater compared with IU (Had prior E/C: IU $73,970, CU $164,223; No prior E/C: IU $53,766, CU $156,356). Although 43.9% of patients initiated IVIg after at least 1 E/C during the preceding year, 53.6% (IU, 491; CU, 381) still experienced at least 1 E/C during the year post-IVIg initiation.

CONCLUSION: CU comprised 43.0% of IVIg initiators, and costs incurred for CU were significantly greater than that for IU. Regardless of the frequency of IVIg treatment, myasthenic exacerbations were still common.