Oral Immunosuppressive Treatment of Myasthenia Gravis in Denmark: A Nationwide Drug Utilization Study, 1996-2013

Although immunosuppressants in the treatment of myasthenia have been available for several decades, population-based studies describing drug utilization in myasthenia patients are scarce. We aimed in this study to describe the treatment of myasthenia in Denmark in more recent years with emphasis on use of oral immunosuppressant agents. We identified a nationwide cohort of incident myasthenia patients in Denmark from 1996 to 2013 and tracked their use of drugs over the entire period using data from nationwide registers. Patients with myasthenia were classified according to utilization of specific immunosuppressants (e.g. prednisolone) as 'never user' or 'ever user'. We used Kaplan-Meier (K-M) and proportion of patients covered (PPC) curves to describe treatment onset and termination. We identified 928 patients (52% female) with incident myasthenia in the study period. Overall, 638 (69%) were treated with prednisolone and 506 (55%) with azathioprine. Treatment with prednisolone and azathioprine within 2 years of myasthenia diagnosis was initiated in 462 (56%) and 366 (45%). Only one of four myasthenia patients (n = 231) did not receive oral immunosuppressive treatment at any time in the study period. Prednisolone was stopped in most patients, whereas treatment with azathioprine was often continued throughout follow-up. In conclusion, we found that treatment of myasthenia in Denmark in recent years corresponded well to the expected clinical course of myasthenia and that most patients underwent long-term immunosuppression.

[Paraneoplastic myasthenia gravis and polymyositis secondary to a thymoma in a young woman]

We present the case of a 33-year-old woman who within weeks developed severe swallowing difficulties and weakness in her limbs to an extent requiring hospitalization. Workup confirmed clinically suspected diagnoses of polymyositis and autoimmune myasthenia. A suspicion of malignant thymoma based on chest computed tomography was histologically verified. Patient treatment and response are presented. The case emphasizes the importance of recognizing that thymomas, in rare instances, may present with a combination of neuromuscular disorders in the same patient.