[Drug exposure associated with exacerbation of symptoms in patients with myasthenia gravis]

Numerous drugs have been related to exacerbation of myasthenia gravis. So far there are no studies examining the extent of use of drugs related to exacerbation of myasthenia gravis.

We sought to assess the extent of use of drugs related to exacerbations and the annual incidence rate of exacerbations in a cohort of myasthenia gravis patients. We explored possible risk factors of severe exacerbations.

We performed a retrospective cohort study. We included adult patients followed in neurology department. We estimated frequencies, rates and built a recurrent events model.

We included 91 patients. 94.51% of patients had at least one prescription of a drug. 51 patients had at least one prescription of a drug contraindicated according to its drug label. 145 exacerbation episodes were reported in 50 patients. The annual incidence rate of exacerbation episodes was 0.35. 48 exacerbations were severe (in 18 patients). The annual incidence rate of severe exacerbation episodes was 0.12. Generalized myasthenia gravis and thymectomy were associated with a higher risk of severe exacerbation episodes.

Our patients were extensive and widespread exposed to drugs during the follow-up period but we did not find and association with severe exacerbation episodes. Just over half of the patients had at least one exacerbation episode during the study period, most of them were mild. Further studies with larger sample sizes are necessary to corroborate these conclusions and to study possible correlations between the use of drugs and the risk of exacerbation episodes.