The Assessment of Gastrointestinal Transit by the Atmo Capsule: A Comparison With the SmartPill Capsule

Background & Aims: Wireless motility capsules (WMCs) can be used to assess gastrointestinal transit time to facilitate diagnosis and treatment of motility disorders. The Atmo Capsule is a novel WMC that measures gases (H₂, CO₂, O₂) and temperature. We aimed to compare and evaluate the performance characteristics of the Atmo Capsule and the SmartPill Capsule (discontinued reference standard WMC) for measurement of gastric emptying time (GET) and colonic transit time (CTT) in patients with confirmed or suspected disordered gastrointestinal transit. Methods: Patients with symptoms indicative of an upper and/or lower gastrointestinal motility disorder ingested the 2 WMCs in a random order. Gastrointestinal transit times were assessed using Spearman correlation and Bland-Altman analysis. Device agreement was assessed for delayed GET (≥5 hours) and CTT (≥59 hours). Results: There were 213 participants from 12 sites, yielding 177 paired GET and 147 paired CTT measurements. The measurements for GET and CTT with the Atmo Capsule and SmartPill Capsule were strongly correlated (GET, R = 0.74, P < .01; CTT, R = 0.69, P < .01), and their observed biases were within 10% of the delayed transit margin. Both delayed GET (68/177) and CTT (56/147) were identified in 38% of participants, with 84% agreement for identification of both delayed GET (sensitivity 68%, specificity 91%) and CTT (sensitivity 83%, specificity 85%). No serious adverse device effects were reported. Conclusions: The performance characteristics of the Atmo Capsule for measurements of GET and CTT were equivalent to the reference standard WMC with a strong correlation and good device agreement. These results demonstrate that the Atmo Capsule is a valid method for evaluating gastrointestinal transit. Clinicaltrials.gov number, NCT05718505.