A high reduction rate of the anti-acetylcholine receptor antibody (AChR Ab) (RR-AChRAb) is associated with favorable results after one year of treatment with immunosuppressants in patients with myasthenia gravis (MG). Neurosurgery and psychiatry. The study also found that remeasuring AChR Ab after 100 days of treatment can help predict 1-year results in AChR Ab-positive patients with MG.
This retrospective study included a total of 53 consecutive AChR-ab positive patients with MG. In all patients, the AChR-Ab level was measured again within a period of 100 days after the start of immunosuppressive therapy (mean AChR-Ab measurement time after treatment: 71 days).
The investigators of the study measured the RR-AChRAb and AChR-Ab levels using the following calculation: (AChR-Ab level before treatment – post-treatment) / AChR-Ab level before treatment / days between the start of therapy and renewed measurement of the AChR-Ab level × 100.
Patients were divided into 2 separate groups based on their ability to achieve minimal manifestation (MM) or better status 1 year after immunosuppressive treatment. The study’s investigators compared the two groups based on the Myasthenia Gravis Foundation of America’s post-intervention status and MG activity of daily living (MG-ADL) at 1 year.
A recipient operating characteristic of RR-AChRAb for achieving the MM or better status after treatment identified 0.64% / day as the RR-AChRAb limit value. Patients with a RR-AChRAb greater than 0.64 were placed in the high group (n = 30), while patients with a value of 0.64 or less were placed in the low RR-AChRAb group (n = 23) have been classified.
Patients in the high RR-AChRAb group had a significantly higher ratio of MM or better status than patients in the low group (90% versus 65%; P = 0.03). In addition, the group with high RR-AChRAb had a lower mean MG-ADL score (1 vs 2; P = 0.04) compared to the group with low RR-AChRAb. In Kaplan-Meier analyzes, the study researchers observed earlier MM attainment in patients with high RR-AChRAb (P = 0.002).
One limitation of this study was the retrospective design, which may have led to selection bias and confounding factors that could have influenced the results.
The study’s investigators concluded that, based on their results, “reassessment of AChR-Ab levels within 100 days of immunosuppressive treatment” “is recommended for selecting treatment and predicting the outcome of AChR-Ab positive MG “.
Kojima Y., Uzawa A., Ozawa Y. et al. The rate of change in acetylcholine receptor antibody levels predicts the outcome of myasthenia gravis. J Neurol Neurosurg Psychiatry. Published online March 25, 2021. doi: 10.1136 / jnnp-2020-325511