Does the pHoenix score reduce the inconclusive GERD diagnosis: a net reclassification index analysis

Acid exposure time (AET) yields inconclusive results in 10%-15% of patients undergoing 24-h ambulatory pH-impedance monitoring (multichannel intraluminal impedance-pH, MII-pH) for suspected gastroesophageal reflux disease (GERD), delaying diagnosis and appropriate management. The pHoenix score (pHx-s) was developed to reduce this diagnostic uncertainty. Its performance in Latin American populations remains uncharacterized.

Net reclassification index (NRI) analysis based on a retrospective cohort.

A cohort of symptomatic adults who underwent high-resolution manometry, MII-pH, and upper endoscopy at Hospital Universitario San Ignacio, Bogotá (Colombia) was included. pHx-s was calculated as (upright AET × 0.991) + (supine AET × 1.286) and classified as normal (<7.06), borderline (7.06-8.45), or pathological (>8.45). Diagnostic performance and area under the receiver operating curve (AUC) were calculated. DeMeester score (>14.7) served as the reference standard. NRI analysis is presented independently for patients with and without confirmed GERD.

292 patients were included in the analysis (Median 61 years, 71.2% female, 79.1% with hiatal hernia (HH)). The AUC of pHx-s was 0.98 (0.963-0.992). At the lower threshold (7.06), sensitivity was 95.7% and specificity 99.1%; at the upper (⩾8.45), sensitivity 89.8%, and specificity 100%. pHx-s reduced inconclusive results from 13.0% (using exclusively AET criteria) to 4.1% (-68.5%, p < 0.001). Among inconclusive AET cases, pHx-s reassigned 55.3% as pathological and 18.4% as normal, with an overall NR improvement of 14.6%.

In this Latin American cohort with a high prevalence of HH, pHx-s substantially reduced inconclusive GERD diagnoses and demonstrated excellent performance compared with the DeMeester score. These findings support the use of the pHx-s in diverse clinical settings.