Myasthenia Gravis Outcomes After Use of Statins and Other Contraindicated Treatments: Results From the French National Insurance Database

BACKGROUND: Clinical guidelines for treating myasthenia gravis (MG) recommend avoiding certain therapies because of a risk of exacerbating MG. We evaluated use of statins and other classically contraindicated therapies and their impact on healthcare outcomes among patients with MG in France. METHODS: This was an observational, retrospective, longitudinal cohort study using data from the French national health insurance database. Adult patients with MG-related claims from 2013 to 2020 were included. The first MG claim date was the index date, with follow-up until end-of-study or death. Multivariable regression models evaluated the risk of intensive care unit (ICU) admission for MG or death during periods of exposure versus nonexposure to contraindicated treatments. RESULTS: Of 14,459 individuals with MG, 12,954 (89.6%) received a contraindicated treatment during follow-up, and 4160 (28.8%) received statins. In multivariable regression analyses, exposure to any contraindicated treatment was not significantly associated with risk of ICU admission for MG (hazard ratio [HR] 1.038; 95% confidence interval [CI] 0.968-1.113; p = not significant) but was associated with significantly higher risk of death (HR 1.167; 95% CI 1.075-1.266; p < 0.001) versus nonexposure. In contrast, statins were associated with a greater risk of ICU admission (HR 1.133; 95% CI 1.065-1.205; p < 0.001) but lower risk of death (HR 0.626; 95% CI 0.565-0.694; p < 0.001). CONCLUSION: This large, real-world study suggests that for some contraindicated medications, including statins, longer-term mortality benefits are likely to outweigh short-term risks of exacerbating MG.