# Diagnostic accuracy of gastric filling ultrasound combined with BMI for gastroesophageal reflux disease

## TL;DR

This study shows that combining gastric filling ultrasound with BMI can help diagnose gastroesophageal reflux disease with reasonable accuracy.

## Contribution

The study introduces a novel combination of gastric filling ultrasound and BMI to dynamically assess GERD with diagnostic accuracy metrics.

## Key findings

- The BMI-based gastric filling ultrasound composite score achieved an area under the curve of 0.826 with an optimal cut-off of 4.50.
- The model demonstrated a sensitivity of 83.75%, specificity of 65.33%, and overall accuracy of 74.84% for diagnosing GERD.
- Decision curve analysis showed the model provided better clinical benefit than 'treat-all' or 'treat-none' strategies.

## Abstract

This study aimed to evaluate the diagnostic accuracy of gastric filling ultrasound, in combination with body mass index (BMI), for the dynamic assessment of gastroesophageal reflux in patients with gastroesophageal reflux disease (GERD)-like symptoms, using 24-h pH impedance monitoring and esophagogastroduodenoscopy (EGD) as reference standards.

We enrolled 155 patients with GERD-like symptoms in our hospital. The results of gastric filling ultrasound, combined with BMI, were compared with 24-h pH impedance monitoring and EGD to assess GERD. Diagnostic accuracy was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Cohen’s kappa statistics. A calibration curve was constructed to assess agreement between the model’s predicted probabilities and the observed outcomes. Decision curve analysis (DCA) was performed to evaluate clinical utility.

GERD patients exhibited significant differences in terms of age, BMI, His angle, and all reflux-related metrics (p < 0.05). The BMI-based gastric filling ultrasound composite score demonstrated an area under the curve of 0.826 with an optimal cut-off of 4.50. Using this threshold, scores 6–8 were defined as GERD; sensitivity was 83.75%, specificity was 65.33%, PPV was 72.04%, NPV was 79.03%, and the overall accuracy was 74.84%. The observed agreement was 0.75, the expected agreement was 0.50, and the kappa was 0.494. The calibration curve indicated good agreement between the model’s predicted probabilities and the observed outcomes, with a mean absolute error of 0.034. Decision curve analysis (DCA) demonstrated that the model provided a superior net benefit over both the “treat-all” and “treat-none” strategies across a wide range of clinically relevant threshold probabilities (approximately 10–65%).

Gastric filling ultrasound is a dynamic imaging technique that visualizes GERD symptoms. The BMI-based gastric filling ultrasound, given its good correlation with 24-h pH impedance monitoring, is a promising auxiliary diagnostic tool for GERD.