Aging and infectious diseases in myasthenia gravis

Abstract

Over the past 120 years, mortality associated with myasthenia gravis (MG) has steadily decreased while the incidence of MG has increased. While mortality due to MG has been ≤5 % for at least the past 25 years, the prevalence of MG has increased. This increase in prevalence of MG may be due, in part, to improvements in diagnostics but also to an aging global population and immunosenescence as the largest increases in MG prevalence have been in patients ≥65 years old.

In fact, a “very late-onset” subtype of MG has been proposed for patients diagnosed at or after age 65 years. These patients are predominantly anti-AChR antibody positive and thymoma negative. Preferred therapeutic options differ based on age at MG onset. Immunosenescence may play a role not only in MG etiology but also in the increased susceptibility of MG patients to infection. Immunosuppressive effects of MG therapies can also increase vulnerability to infection. Despite the improvements in MG treatment, mortality in MG patients remains higher than in the non-MG population. This is partly due to increased vulnerability to infection but also due to infection acting as a precipitating factor for MG exacerbation or crisis.

The increased infection risk inherent with MG and the increased risk resulting from some therapies calls for increased diligence in monitoring and treating infections in MG patients.