A Systematic Review of Hydrogen Breath Testing as a Predictor of Bowel Preparation Quality

Abstract

Introduction: Inadequate bowel preparation causes significant clinical and economic harms. This systematic review aims to assess the accuracy of hydrogen breath testing as a predictor of inadequate bowel preparation. Methods: Studies were identified from MEDLINE, Embase, Web of Science, Cochrane Library, and clinicaltrials. gov. Two investigators evaluated each abstract for the following inclusion criteria: report of correlation between hydrogen breath levels and bowel preparation quality by any scale, prospective design, and non-emergent colonoscopy in adults. Included studies underwent duplicate data extraction using a standardized approach. The quality of studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Results: 159 publications were identified, and 6 unique studies met inclusion criteria, including 4 from full text articles and 2 from abstracts. The number of patients analyzed ranged from 61 to 127. Four studies were performed in the US, 1 in Japan and 1 in Italy. Three studies used a prebiotic in addition to a purgative, with the intention of enhancing the discriminating ability of hydrogen breath levels. Only 3 studies assessed baseline hydrogen levels. In 5 of the 6 studies, hydrogen breath levels were predictive of inadequate bowel preparation. Suggested absolute hydrogen level cutoffs to distinguish adequate from inadequate bowel preparation ranged from 3 to 10 parts per million. Depending on the cutoff value, sensitivity ranged from 71-100% and specificity ranged from 87-100%. There was significant heterogeneity among studies in breath testing protocol and breath analyzer used. Studies provided limited information on the proportion of patients who had altered GI anatomy or were non-hydrogen producers. The full text studies had low risk of bias in most assessed domains. The quality of the abstracts could not be assessed due to limited data. Conclusion: Hydrogen breath levels can be used to predict bowel preparation adequacy, potentially with high reliability, but existing studies have significant limitations. Further studies should use standardized methods and consider the real-world practicality of self-administered home breath testing.