Abstract
BACKGROUND: This systematic review aims to assess the accuracy of hydrogen breath testing as a predictor of bowel preparation. METHODS: Studies were identified from MEDLINE, Embase, Web of Science, Cochrane Library and clinicaltrials.gov. Two investigators evaluated abstracts for inclusion criteria - report of correlation between hydrogen breath levels and bowel preparation quality, prospective design and non-emergent colonoscopy in adults. Included studies underwent duplicate data extraction using a standardized approach. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool assessed quality of the studies. RESULTS: One hundred fifty-nine publications were identified, and six unique studies met inclusion criteria. The number of patients analyzed ranged from 61 to 127. Three studies were performed in the USA, one in Japan and two in Italy. Three studies used a prebiotic in addition to a purgative, with the intention of enhancing the discriminating ability of hydrogen breath levels. Three studies assessed baseline hydrogen levels. In five of the six studies, hydrogen breath levels were predictive of inadequate bowel preparation. Suggested absolute hydrogen levels to distinguish adequate from inadequate bowel preparation ranged from 3 to 10 parts per million. Depending on the cutoff value, sensitivity ranged from 71% to 100% and specificity from 87% to 100%. There was significant heterogeneity among studies in breath testing protocol and breath analyzer used. Full-text studies had low risk of bias in most assessed domains. CONCLUSION: Hydrogen breath levels predict bowel preparation adequacy but existing studies have significant limitations. Further studies should use standardized methods and consider the real-world practicality of self-administered home breath testing.