A novel diagnostic method could yield more accurate results for patients suspected of having myasthenia gravis (MG), according to a recent study in The Lancet.
“This study provides high-level evidence supporting cell-based assay CBA as a first-line assay in the diagnosis and management of MG as well as evaluating patients with suspected MG for whom acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) antibodies are undetectable by radioimmunoprecipitation assay (RIPA) or enzyme-linked immunosorbent assay (ELISA) assays,” the authors wrote.
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This prospective, multicenter cohort study took place in China from January 2021 to September 2022. It included a total of 2043 participants previously diagnosed with MG and 229 individuals without the diagnosis as the control group.
Among the patients with MG, most (n=1110) were generalized MG. In the control group, 73.4% had other neurologic disorders such as peripheral neuropathy, Lamber-Eaton myasthenic syndrome, external ophthalmoplegia, Guillain–Barré syndrome, and amyotrophic lateral sclerosis, among others.
The novel fixed CBA was compared to conventional techniques like RIPA and ELISA.
The study found that the fixed CBA not only improved detection rates of AChR and MuSK antibodies in MG patients by 8.2% to 9.6% and 0.3% to 0.5%, respectively, but also maintained a high specificity (97.8% to 100%) compared to traditional diagnostic methods, such as RIPA, which achieved a specificity of 97.8% to 100%, and ELISA with 94.8% to 99.1%.
These findings suggest that the fixed CBA could emerge as a first-line diagnostic tool for MG, offering higher sensitivity and specificity in patient management, as explained by Li and colleagues.
Moreover, the researchers revealed that while MuSK antibodies constitute a small fraction of MG cases (1% to 4%), the fixed CBA maintained similar sensitivity and specificity for MuSK antibodies as the other assays.
“Despite the very low frequency of anti-AChR or MuSK in nonMG individuals, our results reinforce the notion that definite diagnosis of MG requires clinical manifestations in conjunction with a battery of laboratory tests,” the authors concluded.
Li Z, Zhang C, Chang T, et al. A multicentre, prospective, double-blind study comparing the accuracy of autoantibody diagnostic assays in myasthenia gravis: the SCREAM study. Lancet. Published online July 19, 2023. doi:10.1016/j.lanwpc.2023.100846