The Optimal Duration of pH Monitoring: Testing the Validity of Lyon 2.0 Recommendations for Wireless pH Measurement.

Background & Aims: The Lyon 2.0 consensus recommends 96-hour wireless pH studies for gastroesophageal reflux disease (GERD) diagnosis; however, the optimal length of pH measurement has not been established. Further, it is uncertain if, and under what circumstances, shorter recording times are sufficient for a conclusive diagnosis.

Methods: Data from 944 patients with 4-day recordings was reviewed. Patients were classified at 24, 48, and 72 hours against the 96-hour reference standard. Acid exposure time (AET) <4% was conclusively negative, and AET >6% was conclusively positive for GERD. Esophagitis was an independent marker of disease. The effect of utilizing average day, worst day, and dominant-pattern analysis (≥2 negative or positive days) was compared. Groups defined by AET thresholds from 1% to 7% at 24 and 48 hours were followed to assess when short recording periods were sufficient for conclusive diagnosis.

Results: Diagnostic accuracy improved with study duration (P < .00001). The proportion of patients with inconclusive results (AET 4%-6%) reduced from 113 of 944 at 24 hours to 40 of 113 at 96 hours (35% of subgroup; P = .02), with similar results for dominant pattern analysis. Diagnostic sensitivity for 24-, 48-, and 72-hour pH-monitoring for AET 6% threshold increased with study duration from 62.5% to 76.6% and 88.2%, respectively, when compared with the 96-hour reference standard.

Conclusion: The results of this analysis validate the recommendation that prolonged reflux studies of at least 72 hours duration provide optimal AET measurements for GERD diagnosis. Prolonging studies can also resolve inconclusive results based on 24- and 48-hour studies.