Can the 13C-octanoic acid breath test accurately measure gastric emptying after sleeve gastrectomy and Roux-en-Y gastric bypass? A proof-of concept analysis

Abstract

Background: Bariatric surgery alters gastrointestinal anatomy and physiology, complicating functional assessments such as gastric emptying. The 13C-octanoic acid breath test is a simple, non-invasive alternative to scintigraphy, though its validity in bariatric populations requires further validation.

Methods: For this proof-of-concept analysis, gastric emptying data were derived from a cross-sectional study including individuals with obesity, sleeve gastrectomy, and Roux-en-Y gastric bypass (RYGB). Gastric emptying was measured simultaneously using the ¹³C-octanoic breath test and the reference method, scintigraphy. Gastric emptying half-times (GET_1/2) were compared between the two methods using Wilcoxon signed-rank tests in each group. Concordance between both methods was assessed using Kendall's tau correlation coefficients, and Bland-Altman plots.

Results: No significant inter-method differences were observed for GET_1/2 in any group. Mean differences were -26.7 min (95 % CI: -72.3; 18.6) for obesity, -3.92 min (95 % CI: -30.8; 23.0) for sleeve gastrectomy, and -8.55 min (95 % CI: -21.3; 4.18) for RYGB. Kendall's tau coefficients indicated positive rank associations within each group, but were non-significant (Obesity: 0.8, P = 0.16; sleeve gastrectomy: 0.90, P = 0.13; RYGB: 0.57, P = 0.33). Bland-Altman plots demonstrated acceptable agreement between the measurements across all groups.

Conclusion: This proof-of-concept analysis suggests that the 13C-octanoic acid breath test has potential as a valid, non-invasive method for assessing gastric emptying in post-bariatric surgery patients. However, larger validation studies are warranted to confirm these preliminary findings.

Keywords: Bariatric surgery; Breath test; Gastric emptying; Obesity; Scintigraphy; Validation study.