# Diagnostic performance and safety of the edrophonium test in myasthenia gravis: a retrospective case-control study

## TL;DR

This study evaluates how well and safely the edrophonium test can help diagnose myasthenia gravis, a neuromuscular disorder.

## Contribution

The study provides the first detailed analysis of the diagnostic accuracy and safety profile of the edrophonium test in myasthenia gravis.

## Key findings

- The edrophonium test showed 83.5% sensitivity and 87.7% specificity in diagnosing myasthenia gravis.
- Patients with MuSK-MG had lower odds of a positive edrophonium test compared to those with AChR-MG.
- Most adverse events from the edrophonium test were mild, with 11.5% of patients experiencing any adverse event.

## Abstract

Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction. The diagnosis typically relies on clinical features, serologic testing, and neurophysiological assessment but provocation tests such as the edrophonium test can provide rapid supportive information; however, data on its diagnostic performance are limited. Thus, we aimed to evaluate the diagnostic performance and safety of the edrophonium test in MG.

We conducted a retrospective case–control study of patients who underwent an edrophonium test at the Department of Neurology of the Medical University of Vienna between January 1991 and January 2024. We calculated sensitivity, specificity, and likelihood ratios and performed a multivariable logistic regression analysis to identify variables associated with a positive edrophonium test. Additionally, we assessed the safety of the edrophonium test.

We included 182 patients with MG (41.2% female; mean age 55.8 years) and 324 controls (55.2% female; mean age 53.6 years). The edrophonium test had a sensitivity of 83.5% and a specificity of 87.7% in diagnosing MG. Patients with a decrement after repetitive nerve stimulation had higher odds of a positive response to the edrophonium test (OR 3.79, 95% CI 1.48–10.33, p = 0.0067), while odds were lower in patients with MuSK-MG compared to patients with AChR-MG (OR 0.08, 95% CI 0.01–0.82, p = 0.0254). Adverse events were reported in 58 patients (11.5%), in most of whom (53 patients, 91.4%) they were mild.

We provide data on the diagnostic performance and safety of the edrophonium test, supporting its use as an adjunctive diagnostic test for the diagnosis of MG.

The online version contains supplementary material available at 10.1186/s42466-026-00468-6.