Several factors were found to be associated with a higher likelihood of minimal symptom expression in myasthenia gravis (MG) at 12 months based on a study published in Muscle & Nerve. Minimal symptom expression in the study was defined as an MG Activity of Daily Living (MG-ADL) score of 0 or 1.

The factors were discovered through analysis of 12-month data in the MG Patient Registry and included having a low disease burden at baseline, improvement at 6-month follow-up, and no use of pyridostigmine. Low numbers of patients were able to achieve minimal symptom expression, however.

“In both groups, but more so in the high-burden group, patients infrequently achieved [minimal symptom expression] after 1 year of MG treatment,” the authors said.

Overall, the patient population included in the study showed gradual improvement and over 30% of patients had significant improvement (>2 point decrease in MG-ADL) over 12 months.

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The patients included in the study were grouped into 2 categories, high-burden (MG-ADL ≥6) and low-burden (MG-ADL <6), with roughly equal numbers of participants (n=248 and n=272, respectively).

Significant improvement was observed more often in the high-burden group than in the low-burden group. The authors said that this was most likely due to the fact that the low-burden group was already at or very close to minimal MG-ADL scores and that improvement of 2 points might be very difficult or impossible.

Patients in the high-burden group tended to have more frequent MG exacerbations compared to the low-burden group. High-burden patients also tended to require an escalation in treatment whereas most of the low-burden group had no change in medication at the 6- and 12-month timepoints.

Using multivariable logistic regression analysis, the study found that patients with a low baseline disease burden, those who showed improvement in MG-ADL at 6 months follow-up, and patients who did not require pyridostigmine use had a higher likelihood of achieving minimal symptom expression by 12 months. 

Reference

Lee I, Leach JM, Aban I, McPherson T, Duda PW, Cutter G. One-year follow up of disease burden and medication changes in patients with myasthenia gravis: from the MG Patient Registry. Muscle Nerve. Published online June 8, 2022. doi:10.1002/mus.27659