Optimal cutoff value of integrated relaxation pressure on the esophagogastric junction to detect outflow obstruction using starlet high-resolution manometry system

Background Achalasia and esophagogastric junction outflow obstruction (EGJOO) are idiopathic esophageal motility disorders characterized by impaired deglutitive relaxation of the lower esophageal sphincter (LES). High-resolution manometry (HRM) provides integrated relaxation pressure (IRP) which represents adequacy of LES relaxation. The Starlet HRM system is widely used in Japan; however, IRP values in achalasia/EGJOO patients assessed with the Starlet system have not been well studied. We propose the optimal cutoff of IRP for detecting achalasia/EGJOO using the Starlet system. Methods Patients undergone HRM test using the Starlet system at our institution between July 2018 and September 2020 were included. Of these, we included patients with either achalasia or EGJOO and those who had normal esophageal motility without hiatal hernia. Abnormally impaired LES relaxation (i.e., achalasia and EGJOO) was diagnosed if prolonged esophageal emptying was evident based on timed barium esophagogram (TBE). Results A total of 111 patients met study criteria. Of these, 48 patients were diagnosed with achalasia (n = 45 [type I, n = 20; type II, n = 22; type III, n = 3]) or EGJOO (n = 3). In the 48 patients who had a prolonged esophageal clearance based on TBE, IRP values distributed along a wide-range of minimal 14.1 to a maximal of 72.2 mmHg. The optimal cutoff value of IRP was 24.7 mmHg with sensitivity of 89.6% and specificity of 84.1% (AUC 0.94). Conclusion The optimal cutoff value of IRP to distinguish achalasia/EGJOO was >= 25 mmHg using the Starlet HRM system in our cohort. This indicates that the current proposed cutoff of 26 mmHg appears to be relevant.