pH Meter and pH Paper May Be Useful for Monitoring Tube-Fed Children With Neurologic Impairment and GERD

The pH meter and pH paper point-of-care tests correlate well with the laboratory pH meter, indicating that they may be useful in point-of-care testing for monitoring gastric pH in tube-fed children with neurologic impairment and gastroesophageal reflux disease (GERD). These findings were reported in the Journal of Pediatric Gastroenterology and Nutrition.

This prospective, observational study included 43 children (median age, 4 years; range, 2 weeks to 15 years; 51.2% male) with neurologic impairments and gastrostomy tubes who were diagnosed with GERD. Among the cohort, the most common neurologic diagnoses were unspecified developmental delay (46.5%), trisomy 21 (20.9%), and cerebral palsy (14%).

The investigators measured participants’ gastric pH with the pH paper, handheld pH meter, and the laboratory pH meter, which is the gold standard. They then assessed agreement among the techniques with use of the intra-class correlation coefficient (ICC), Bland-Altman analysis, and kappa statistic.

A total of 67 gastric samples were assessed. The ICC was 0.75 (95% Confidence Interval [CI], 0.69-0.97) between the handheld and laboratory meters, 0.69 (95% CI, 0.63-0.94) between the pH paper and laboratory meter, and 0.69 (95% CI, 0.63-0.94) between the handheld meter and paper.

Bland-Altman analysis between the handheld and lab meters showed a mean difference of

–0.03 pH units (limits of agreement: –0.52-0.47 pH units), and between the paper and lab meter a difference of 0.17 pH units (limits of agreement: –0.99-1.33 pH units).

The kappa coefficient for the 43 samples obtained from the handheld pH meter and laboratory pH meter using a cutoff pH of 4.0 was 1.0 (95% CI, 1.0-1.0), and the kappa coefficient for the samples obtained from the pH paper and laboratory pH meter using a cutoff pH of 4.0 was 0.9 (95% CI, 0.77-1.0).

“The findings suggest that both point-of-care tests, the pH meter and pH paper, correlate well with the gold standard for testing pH with a laboratory pH meter, indicating usefulness in point-of-care testing for monitoring gastric pH in tube-fed children with neurologic impairments and GERD,” stated the study authors.

Among several potential limitations of this study, the investigators noted regarding the use of pH paper for bedside spot gastric pH measurements, the optimal number of samples to collect from a single patient to obtain a reliable measurement is still unclear. Comparative data are lacking between the use of spot pH paper and traditional pH metrics. Additionally, the small sample size may have limited the precision of the estimates of agreement.

“Although the point estimates measuring extent of agreement and clinical validity for the meter were higher than that for pH paper, the clinical significance of this difference may be marginal, and pH paper is likely also a useful tool for monitoring gastric pH in this population,” the researchers commented.

Reference

Tjon J, Cooper M, Pe M, et al. Measuring gastric pH in tube-fed children with neurologic impairments and gastroesophageal disease. J Pediatr Gastroenterol Nutr. Published online February 17, 2021. doi: 10.1097/MPG.0000000000003087