Regional gastrointestinal transit and pH studied in 215 healthy volunteers using the wireless motility capsule: influence of age, gender, study country and testing protocol

BackgroundThe wireless motility capsule (WMC) offers the ability to investigate luminal gastrointestinal (GI) physiology in a minimally invasive manner. AimTo investigate the effect of testing protocol, gender, age and study country on regional GI transit times and associated pH values using the WMC. MethodsRegional GI transit times and pH values were determined in 215 healthy volunteers from USA and Sweden studied using the WMC over a 6.5-year period. The effects of test protocol, gender, age and study country were examined. ResultsFor GI transit times, testing protocol was associated with differences in gastric emptying time (GET; shorter with protocol 2 (motility capsule ingested immediately after meal) vs. protocol 1 (motility capsule immediately before): median difference: 52min, P=0.0063) and colonic transit time (CTT; longer with protocol 2: median 140min, P=0.0189), but had no overall effect on whole gut transit time. Females had longer GET (by median 17min, P=0.0307), and also longer CTT by (104min, P=0.0285) and whole gut transit time by (263min, P=0.0077). Increasing age was associated with shorter small bowel transit time (P=0.002), and study country also influenced small bowel and CTTs. Whole gut and CTTs showed clustering of data at values separated by 24h, suggesting that describing these measures as continuous variables is invalid. Testing protocol, gender and study country also significantly influenced pH values. ConclusionsRegional GI transit times and pH values, delineated using the wireless motility capsule (WMC), vary based on testing protocol, gender, age and country. Standardisation of testing is crucial for cross-referencing in clinical practice and future research.