Background There is no prognostic test to predict generalized myasthenia gravis (GMG) risk in patients with ocular disease. We aimed to create a predictive risk score.
Method Multi-centre retrospective cohort study: OMG for minimum 3 months, untreated with immunosuppression for minimum 2 years or until GMG onset.
Results 101 (57F) patients included. Median follow-up 8.4 y(2–42) from onset. 31 developed GMG at median 1.31 y (3.5 mo–20.2 y); 19 within 2 y.
3 significant predictors from univariable logistic regression analysis (p<0.10); adjusted ORs in multivariable model (Chi-square p=0.001): seropositivity 5.63 (1.42,22.33); presence of ≥1 comorbidity including autoimmune disorders 5.56 (0.66,46.62); thymic hyperplasia 6.66 (0.45,98.01).
Prognostic score derived from the coefficients of the logistic model: sum of the points(one point for presence of each of the above predictive factors); classified ‘low risk’ if ≤1, ‘high risk’ if ≥2. Predicted probabilities: 0.07 (SD 0.03) for ‘low risk’, 0.39(SD 0.09) for ‘high risk’. Negative predictive value 91%(79,98), positive predictive value 38% (23,54), area under ROC curve 0.74 (0.64,0.85).
Conclusions We present one of the few natural history studies on OMG and create the first predictive score to prognosticate the risk of GMG. This approach of risk stratification moves us towards addressing the question of modifying GMG risk in high-risk patients.