Late-onset generalized myasthenia gravis: clinical features, treatment, and outcome.

Late-onset myasthenia gravis (LOMG) is a unique MG subgroup. More information is needed on its subgroups such as non-thymomatous generalized LOMG. We evaluated the effect of demographic, clinical, and serological factors as well as different immunosuppressive modalities on outcome in generalized non-thymomatous LOMG with onset ≥ 50 years. Myasthenia Gravis Foundation of America (MGFA) Clinical Classification, MGFA postintervention score (MGFA PIS) and MG Composite scores were obtained to define the severity of disease and clinical outcome. In 95 patients with generalized non-thymomatous LOMG, 60 (63%) were men, 45 (47%) had mild disease, 80 (84%) were anti-AChR, and 56 (61%) were anti-titin positive. In those who received immunosuppressives and provided the clinical scores (84 patients), 50 (60%) had favorable outcome (MGFA PIS categories of complete stable remission, pharmacological remission and minimal manifestations) at the end of 3 years. Use of prednisone + azathioprine had significantly positive effect on outcome. The presence of anti-titin antibodies had no significant effect on severity and outcome. Five anti-MuSK-positive patients had favorable outcome. In conclusion, the presence of neither anti-titin nor anti-MuSK antibodies points to unfavorable outcome. Prednisone and azathioprine combination has beneficial effects in non-thymomatous generalized LOMG.