Long-Term Adverse Effects and Survival in Patients with Myasthenia Gravis Treated with Azathioprine: A Retrospective Cohort

Objective: The objective of this retrospective cohort is to analyze survival and other outcomes in patients with myasthenia gravis treated with azathioprine in comparison to the standard treatment based on pyridostigmine and corticosteroids. Methods: A retrospective cohort of 90 patients with myasthenia gravis were followed up on for a mean period of 103.8 months. Survival/mortality was compared between patients receiving azathioprine and those on standard treatment with pyridostigmine and prednisone. Survival analysis was performed with the method of Kaplan-Meier and the Cox proportional hazards model. The long-term side-effects were also reported. Results: The patients on azathioprine had a longer survival according to the unadjusted log-rank test. However, in the multivariate analysis, age at baseline was the only predictor of any cause mortality (HR: 1.12; 95% CI: 1.06-1.19), but not the use of azathioprine (HR: 0.30; 95% CI: 0.10-1.43). Some malignancies appeared in patients treated for more than 10 years. Hematological abnormalities such as leucopenia, anemia, and pancytopenia occurred in four patients and malignancies in three. Conclusions: The use of azathioprine in MG did not result in longer survival compared to standard treatment. Some hematological alterations and malignancies may appear over time in patients receiving azathioprine.