Measuring Adverse Event Burden in Myasthenia Gravis: Retrospective Validation of the Adverse Event Unit With Randomized Trial of Thymectomy in Myasthenia Gravis Data.

Introduction/aims: The Adverse Event Unit (AEU) is a patient and physician weighted unit that quantifies and compares adverse event (AE) burden among any neurologic treatments. A recent study demonstrated feasibility and preliminary validity of the AEU in myasthenia gravis (MG). This study evaluated feasibility of assigning AEU scores retrospectively from pre-existing data in the randomized clinical trial of thymectomy in MG (MGTX) and quantifying AE burden differences in participants.

Methods: Serious and non-serious AE were recorded at MGTX visits. AEU scores were assigned by matching MGTX AE to AEU categories. Total AEU score for each participant was compared to the prednisone dosage area under the curve for years 1, 2, and 3. We also compared differences in AEU scores between participants treated with prednisone and azathioprine versus those treated with prednisone alone.

Results: All 117 MGTX patients received prednisone; 32% also received azathioprine. A weak correlation between increasing prednisone exposure and total AEU score was observed at year 2 (r = 0.19, p = 0.04) and year 3 (r = 0.23, p = 0.01). Participants treated with azathioprine in addition to prednisone had higher AEU scores than patients treated with prednisone alone at years 1 (median AEU 19 vs. 5, p = 0.037), 2 (median AEU 23 vs. 6, p = 0.018), and 3 (median AEU 34 vs. 9, p = 0.006).

Discussion: Pre-existing clinical trial data can be translated into AEU scores. MG patients treated with multiple immunosuppressants had the highest AEU scores, similar to our prospective trial. Future studies will compare the side effect burden of MG treatments and define clinically meaningful AEU scores.