METHODS: This retrospective multicenter study included adults who underwent high-resolution manometry (HRM) for NOD at two tertiary hospitals in Malaysia from 2014 to 2023. Diagnoses were classified according to Chicago Classification v3.0. Clinical predictors of achalasia were evaluated. The discriminatory performance of rapid drink challenge (RDC)-integrated relaxation pressure (IRP) in differentiating achalasia from non-achalasia was explored.
RESULTS: Among 230 patients (mean age 53.3; 47.0% male), achalasia was identified in 23.9%, esophagogastric junction outflow obstruction (EGJOO) in 17.3%, and ineffective esophageal motility in 24.8%. Weight loss (adjusted OR 2.99, 95% CI 1.25-7.15, p = 0.014), absence of dyspepsia (adjusted OR 0.09, 95% CI 0.02-0.45, p = 0.004), and presence of nausea/vomiting (adjusted OR 3.35, 95% CI 1.34-8.40, p = 0.010) independently predicted achalasia. RDC-IRP demonstrated strong discrimination between achalasia and non-achalasia (AUC 0.894, 95% CI 0.794-0.993, p Achalasia constitutes a substantial proportion of patients evaluated for NOD in tertiary care settings. Specific clinical features may aid early recognition. RDC may provide incremental diagnostic value and may serve as a practical adjunctive tool in differentiating achalasia from EGJOO.