Association Between Serum Anti-Acetylcholine Receptor (AChR-Ab) Titers and Clinical Outcomes in Patients with Ocular-Onset Myasthenia Gravis: An Academic Retrospective Cohort Study

Abstract

Background: Acetylcholine receptor antibodies (AChR-Ab) are established biomarkers in myasthenia gravis (MG). In ocular MG (OMG), their presence has been linked to disease severity, treatment response, and progression to generalized MG (GMG); however, the relevance of AChR-Ab titers or seropositivity to ocular manifestations remains uncertain. Objective and Method: We retrospectively reviewed OMG patients treated at Rajavithi Hospital (2009–2024). AChR-Ab titers were measured using enzyme-linked immunosorbent assay (ELISA). Clinical and demographic factors associated with AChR-Ab seropositivity (AChR-Ab⁺) and their titers were evaluated using logistic and linear regression analyses. Results: Among the 111 patients with OMG, 51 patients (45.9%) were AChR-Ab⁺ and 60 patients (54.1%) were AChR-Ab-seronegative (AChR-Ab⁻). The AChR-Ab⁺ group demonstrated a trend toward younger age compared to the AChR-Ab⁻ group (43.82 ± 6.55 vs 46.53 ± 7.71 years; p = 0.051). AChR-Ab⁺ patients were more likely to present with diplopia, a higher risk of progression to GMG, and more prevalence of thymoma, whereas ptosis was commonly observed in the AChR-Ab⁻ group. Gender distribution, autoimmune comorbidities, the use and dosages of pyridostigmine or prednisolones were comparable between groups. Advanced age at onset was associated with lower likelihood of AChR-Ab⁺ (OR 0.922; 95% CI: 0.864–0.983, p = 0.014). Diplopia (OR 5.394; 95% CI: 1.280–22.723, p = 0.022), progression to GMG (OR 4.640; 95% CI: 1.155–18.639, p = 0.031), and thymoma (OR 9.978; 95% CI: 2.094–47.547, p = 0.004) were positively associated with AChR-Ab⁺ status. Regarding AChR-Ab titers, the presence of thymoma (β =1.556; 95% CI: 0.353–2.761, p = 0.012) was independent predictors, while titers declined with age, most pronounced after 50 years. Conclusion: Serostatus of acetylcholine receptor antibodies may be useful for identifying MG patients at higher risk of generalization or thymoma, while antibody titers may provide complementary information, particularly in relation to thymoma, rather than serving as direct markers of disease severity or ocular manifestations.