Prediction of myasthenia gravis generalization under immunosuppressive therapy in Northwest China

Abstract Objective It is well demonstrated that immunosuppressants can reduce, but not eliminate the risk of generalized development in ocular myasthenia gravis (OMG). Herein, we explored the potential predictors of conversion of OMG patients receiving immunosuppressive treatments. Methods OMG patients under immunosuppressive treatments in Tangdu Hospital from June 2008 to June 2012 were retrospectively reviewed. Baseline clinical characteristics were documented. Patients were followed up regularly by face-to-face interview to evaluate clinic status and treatment efficacy. Main outcome measure was generalized conversion and the relative data were collected and analyzed by logistic regression. Results 223 eligible OMG patients completed the final follow-up visit and 38 (17.0%) progressed to generalized MG (GMG) at a median interval of 0.9 year. Patients with adult onset and positive repetitive nerve stimulation (RNS) of facial or axillary nerve had higher conversion rate than those with juvenile onset and negative RNS ( p = 0.001; p = 0.019; p = 0.015, respectively). Adult-onset patients converted earlier than juvenile-onset OMG patients ( p = 0.014). Upon multivariate logistic regression analysis, age of onset (Odds ratio [OR] 1.023, 95% confidence interval [CI] 1.006–1.041, p = 0.007) and positive facial nerve RNS (OR 2.826, 95%CI 1.045–5.460, p = 0.038) were found to be positively associated with generalized development. Moreover, an obviously negative association was found for disease duration (OR 0.603, 95%CI 0.365–0.850, p = 0.019). Conclusions Age of onset, disease duration and facial nerve RNS test can predict conversion of OMG under immunosuppressive treatment. Adult-onset, shorter disease duration and facial nerve RNS-positive patients have a higher risk of generalized development.