pHoenix score discriminative ability in suspected gastroesophageal reflux disease: a high-volume single-center external validation.

The pHoenix score was recently developed to reduce the proportion of inconclusive diagnoses associated with using total acid exposure time (AET) alone. The aim of this study was to compare the discriminative performance of the pHoenix score to total AET and DeMeester score (DMS) in patients undergoing 24-hour transnasal pH-monitoring (24-h pH). This cross-sectional study included consecutive patients (2017-2024) undergoing 24-h pH for suspected gastroesophageal reflux disease. Exclusions criteria were prior foregut/bariatric procedures, outflow obstruction disorders and inadequate pH-studies (<18 hours). The pHoenix score calculation was (%upright AET × 0.991) + (% supine AET × 1.286), with thresholds: <7.06 (normal), 7.06-8.45 (borderline), >8.45 (pathological). Total AET thresholds were: <4% (normal), 4-6% (borderline), and >6% (pathological). The DMS (pathological if >14.72) was the reference standard. Of 500 patients (50% females, median age 51 years, median BMI 24.65 kg/m2), 213 (43%) had pathological DMS. The pHoenix score and total AET identified a similar proportion of normal cases (54% vs. 56.2%, P > 0.99), but different pathological (40.4% vs. 30%, P < 0.01) and borderline diagnoses (5.6% vs. 13.8%, P < 0.01; with a 59% reduction with the pHoenix score). The pHoenix model showed strong performance (pseudo R2:0.877; Akaike information criterion = 83.57). Sensitivity/specificity were high at both 7.06 (99.1%/93.4%) and 8.45 (93.9%/99.3%) cutoffs. The AUC was 0.995 (95% CI: 0.987-1) for the pHoenix score, and 0.992 (95% CI: 0.987-0.997) for total AET. The pHoenix score, while maintaining a high diagnostic accuracy, offers a refined classification of acid exposure weighting supine/upright AET, thus reducing borderline diagnoses and potential need for further testing.