In patients with ocular myasthenia gravis (MG), a higher baseline body mass index (BMI) may elevate the risk of progression to generalized MG, according to findings recently published in the Orphanet Journal of Rare Diseases.
In ocular MG, only the muscles that help move the eyes and eyelids are impacted, with symptoms including drooping eyelids and double vision. Many patients with ocular MG will eventually develop generalized MG, which affects muscles throughout the body.
While some studies have suggested that a higher BMI is linked to various complications of MG, others have found that an increased BMI could improve short-term outcomes. “Due to the variability in results and the limited sample sizes of previous studies, a large-scale observational study is necessary to clarify the role of BMI in MG patients,” the authors explained.
The study included 940 patients, 391 of whom had ocular MG, from several medical centers throughout China. Patients with a BMI lower than 24 kg/m2 were classified as low BMI, while those with a BMI of 24 kg/m2 or greater were classified as high BMI.
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Patients in the high BMI group were more likely to be female, older and have a shorter disease duration. Additionally, patients with high BMI were more likely to test positive for antibodies that attack the protein acetylcholine receptor (AChR), which is found in neuromuscular junctions.
Participants were followed for a median of 33 months. Of the low BMI patients with ocular MG, 20% progressed to generalized MG, compared to 31.3% of those with a high BMI.
Findings revealed that 75.2% of patients received immunotherapy during the follow-up period, with a higher proportion of low BMI participants receiving the treatment. However, the authors noted that the association between higher BMI and disease progression remained the same even after adjusting for immunotherapy and other factors.
As a secondary measure, the study also assessed changes in the MG Activities of Daily Living (ADL) score, which evaluates how the disease impacts various measures of functional ability. At follow-up, 93.3% of patients experienced improvements in ADL scores, with no significant differences by BMI.
Based on these results, the authors support further investigation into the potential causal relationship between BMI and MG progression.
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