Introduction

The Lyon 2.0 Consensus accepts that wireless pH monitoring provides equivalent information to catheter-based studies and recommends 96-hr wireless pH studies for gastroesophageal reflux disease (GERD) diagnosis.¹ However, the pH sensor may detach early, and 24-hr and 48-hr studies are routine (and cost-efficient) in many centers. Published studies have used different analyses to summarize prolonged pH data, including “average acid exposure time (AET),” “worst-day AET,” and “dominant pattern analysis."

Aims & Methods

This study aimed to determine (i) when a shorter recording time is sufficient for conclusive diagnosis of GERD; (ii) the impact of prolonged pH studies on patients with an inconclusive diagnosis of GERD based on 24- and 48-hr measurements; (iii) the replicability and diagnostic yield of 24-hr, 48-hr, and 72-hr studies compared with the 96-hr reference standard; (iv) the performance of different analyses of prolonged pH data.
We analyzed endoscopy and pH data from 944/2045 (46%) consecutive patients (age 46.5 ± 14.6 years, 65% F) referred for investigation of typical reflux symptoms off medication that had at least 92-hr measurement. Patients were classified at 24, 48, and 72-hr against the 96-hr reference standard. AET <4% was considered conclusively negative, and AET >6% conclusively positive for GERD. Los Angeles (LA) esophagitis was an independent marker of disease. The effect of prolonging pH measurement on GERD diagnosis was evaluated using average day, worst-day, and dominant pattern analysis (≥2 negative or positive days). Receiver operating curve (ROC) analysis was performed on the 24- and 48-hr pH data in patients with normal endoscopy, LA A and B esophagitis. Groups defined by 24-hr AET thresholds from 1% to 7% were followed up to 96 hr to assess when 24-hr data were sufficient for conclusive diagnosis.

Results

The proportion of patients with inconclusive results (average AET 4-6%) reduced from 113 at 24 hours to 40 at 96 hours (35% of the subgroup; p=0.02), with similar results for dominant pattern analysis, but not for worst-day analysis (p=0.2). When 24- and 48-hr test periods were assessed, prolonging average day studies to 72 and 96 hr increased conclusive GERD diagnosis to 71% and 65%, respectively. On dominant pattern analysis, prolonging pH studies up to 96-hr in the subgroup of patients with inconclusive diagnoses at 48-hr showed a decrease in inconclusive diagnoses from 100% to 59% (p < 0.05). A stepwise improvement in diagnostic accuracy and yield was observed from 24, 48, and 72-hr measurements compared to the 96-hr reference standard (p<0.00001 for trend).
On ROC analysis, 24-hr AET > 6.4% and 48-hr AET > 6.1% predicted GERD based on 96-hr measurements in all patients with normal endoscopy (table). 93% of patients with LA grade B esophagitis had AET >6%. Only 2.6% of patients with a 24-hr AET ≤ 2.0% had GERD at 96 hr. Over 93% of these had physiologic acid exposure (AET <4%) on reference standard 96-hr studies. When the analysis was repeated for 48-hr data, there was a <1% probability of GERD at 96 hr.

Conclusion

This study confirms that prolonging studies from 24-hr catheter-based or 48-hr wireless pH measurements to ≥72-hr is sufficient for conclusive GERD diagnosis; however, clearly negative (< 2% AET) or positive results (> 6% AET) from 24-hr studies are sufficient to exclude or confirm GERD. Prolonged pH studies of up to 96-hr duration improve the diagnostic yield for conclusive GERD. Analysis methods that utilize average day AET or dominant pattern are preferred.

References

1. Gyawali CP, Yadlapati R, Fass R, et al. Updates to the modern diagnosis of GERD: Lyon consensus
2.0. Gut 2024;73(2):361-371.