Serostatus Testing Patterns Among Individuals with Myasthenia Gravis: Implications for Patient Care
Joshua N. Liberman1, Jacqueline Pesa2, Jonathan D. Darer1, Xiaoyun Yang1, Louis Jackson2, Artem Sergeyenko2, Nolan Campbell2, Richard Nowak3
1Health Analytics, LLC, 2Janssen Scientific Affairs, LLC, a Johnson & Johnson company, 3Yale University School of Medicine
Objective:
To evaluate real-world myasthenia gravis (MG) serostatus testing patterns.
Background:
Serologic antibody testing supports myasthenia gravis (MG) diagnosis and informs appropriate treatment.
Design/Methods:
Using U.S. insurance claims linked to serostatus results, a retrospective, observational cohort study was conducted among 5,788 adults with newly diagnosed MG between 01-January-2018 and 30-June-2022 with 12-months claims history prior to and following diagnosis. Serostatus tests included acetylcholine receptor (anti-AChR), muscle-specific kinase (anti-MuSK), and low-density lipoprotein receptor-related protein 4 (anti-LRP4) antibodies. Analysis included descriptive characteristics of serostatus results and testing, and receipt of MG-related treatments (corticosteroids, acetylcholinesterase inhibitor (AChEI), IVIg, non-steroidal immunosuppressants, plasmapheresis) following diagnosis. Demographics, insurance, comorbidities, and diagnosing specialty and location were regressed on receiving a serostatus test (yes vs. no).
Results:
Of 5,788 cases, 2,590 (44.7%) had at least one valid serology test result: 1,453 (56.3%) seronegative, 1,094 (42.4%) anti-AChR+, 28 (1.1%) anti-MuSK+, and 5 (0.2%) anti-LRP4+. Among seronegative, 56.6% were only tested for anti-AChR antibodies, 33.7% tested both anti-AChR and anti-MuSK antibodies, and 5.0% tested all three antibodies. Overall, 69.5% received MG-related treatment in the year following diagnosis. Of the seronegative and untested populations, 40.9% and 37.4% initiated ≥2 unique MG treatments, with 699 (69.4%) and 1,267 (64.7%) initiating AChEI. Patients with commercial or Medicaid insurance (vs Medicare), higher Charlson Comorbidity Index, area with population below federal poverty, and rural (vs urban) were less likely to be tested. Neurologist diagnosis, baseline EMG testing, and select MG symptoms were associated with higher likelihood of serostatus testing.
Conclusions:
Variation in MG serologic testing, including infrequent MuSK and LRP4 autoantibody testing among seronegative patients, highlights a potential need to promote best practices in patient care. While claims data has clear limitations, it suggests that education on the topic of antibody subtypes is needed especially in the era of targeted therapy decisions based on serostatus.
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