Erratum to “Omari T. Addendum to A study of dysphagia symptoms and esophageal body function in children undergoing anti-reflux surgery”

I refer to my Letter to the Editor entitled “Addendum to A study of dysphagia symptoms and esophageal body function in children undergoing anti-reflux surgery”¹ suggesting that the pressure-flow index (PFI) composite score, based on high-resolution manometry (HRM) with impedance, may predict risk for dysphagia in children undergoing Nissen fundoplication for primary gastro-esophageal reflux disease.

We recently discovered an inconsistency with the Medical Measurement Systems (MMS) analysis software that was used to acquire the manometry pressure data that was reported in the Letter. Specifically, MMS studies that are exported to ASCII-file format will be in cm H2O units even though acquired and displayed by the MMS system in mm Hg units (1 mm Hg would be exported as 1.36 cm H2O).²

The PFI includes two pressure variables for derivation. Due to the error, these variables need to be divided by a factor 1.36 to convert cm H2O to mm Hg. As an erratum to the Letter, readers should be aware that the presented values for PFI need correction by dividing by a factor of 1.85 (1.36²). The correct predictive thresholds for PFI, as a dichotomous predictor of a postoperative dysphagia, are PFI >65, to predict any dysphagia, and PFI >114, to predict a dysphagia score >10. The associated values for sensitivity and specificity of the new thresholds are unchanged.