Clinical Utility of Acetylcholine Receptor Antibody Testing in Ocular Myasthenia Gravis

Abstract

The sensitivity of acetylcholine receptor (AChR) antibody testing is thought to be lower in ocular myasthenia gravis (OMG) compared with generalized disease, although estimates in small-scale studies vary. There is little information in the literature about the implications of AChR antibody levels and progression from OMG to generalized myasthenia gravis.OBJECTIVES To test the hypothesis that serum AChR antibody testing is more sensitive in OMG than previously reported and to examine the association between AChR antibody levels and progression from OMG to generalized myasthenia gravis. DESIGN, SETTING, AND PARTICIPANTS A retrospective, observational cohort study was conducted of 223 patients (mean [SD] age, 59.2 [16.4] years; 139 [62.3%] male) diagnosed with OMG between July 1, 1986, and May 31, 2013, at 2 large, academic medical centers.MAIN OUTCOMES AND MEASURES Baseline characteristics, OMG symptoms, results of AChR antibody testing, and progression time to generalized myasthenia gravis (if this occurred) were recorded for each patient. Multiple logistic regression was used to measure the association between all clinical variables and antibody result. Kaplan-Meier survival analysis was performed to examine time to generalization. RESULTS Among the 223 participants, AChR antibody testing results were positive in 158 participants (70.9%). In an adjusted model, increased age at diagnosis (odds ratio [OR], 1.03; 95% CI, 1.01-1.04; P = .007) and progression to generalized myasthenia gravis (OR, 2.92; 95% CI, 1.18-7.26; P = .02) were significantly associated with positive antibody test results. Women were less likely to have a positive antibody test result (OR, 0.36; 95% CI, 0.19-0.68; P = .002). Patients who developed symptoms of generalized myasthenia gravis had a significantly higher mean (SD) antibody level than those who did not develop symptoms of generalized myasthenia gravis (12.7 [16.5] nmol/L vs 4.2 [7.9] nmol/L; P = .002). CONCLUSIONS AND RELEVANCEWe demonstrate a higher sensitivity of AChR antibody testing than previously reported in the largest cohort of patients with OMG available to date. Older age, male sex, and progression to generalized myasthenia gravis were significantly associated with a positive antibody test result. In addition, to our knowledge, this is the first report of an association between high AChR antibody levels and progression from OMG to generalized disease.

Low conversion rate of ocular to generalized myasthenia gravis in Singapore

“…The main finding in this study is the low conversion rate of OMG to GMG in an Asian population, estimated at 7.7% at 2 years of follow‐up after diagnosis and at 10.6% at median follow‐up of 40.8 months. This is in contrast to earlier findings in Caucasians, which varied from 50% to 20%–31% . It is possible that the genetic background of Asians explains the lower conversion rate.…”

“…This is in contrast to earlier findings in Caucasians, which varied from 50% 19 to 20%-31%. 3,6,8,20 It is possible that the genetic background of Asians explains the lower conversion rate. However, alternative explanations may also exist, including false OMG diagnoses and/or role of immunosuppression in reducing the conversion rate.…”

Ocular Myasthenia: Clinical Features and Diagnosis

“…The binding antibody is highly specific but is thought to be less sensitive in OMG compared to generalized disease [17]. However, in the study conducted by Peeler et al, a higher sensitivity of AChR antibody was demonstrated in OMG patients in the rate of 70.9% [18]. The authors suggested that older age, male sex and progression to generalized disease were significantly associated with a positive antibody result.…”

“…Previous reports showed a trend toward frequent progression to generalized form of MG in older individuals [10]. In addition, high AChR antibody titers at presentation have been found to be associated with increased risk of generalization [11]. Previous studies showed increased risk of conversion with thymoma [12], while there is some evidence in the literature showing thymectomy to be effective in controlling juvenile OMG by reducing the risk of generalization [13].…”

Diagnosis of Tensilon-Negative Ocular Myasthenia Gravis By Daily Selfie

“…Yet, these tests can overlook patients with pure ocular myasthenia gravis (2). Standard laboratory assays for acetylcholine receptor antibody levels are often negative (3,4). Tensilon testing, which some physicians are reluctant to perform, lacks sufficient sensitivity to identify many patients (5).…”