A real-world assessment of healthcare resource utilization following IBS-Smart

Background: IBS is a disorder of gut-brain interaction that is diagnosed positively but still requires a focused differential diagnosis and limited rule-out testing. IBS-Smart and Trio-Smart are commercially available serologic and breath tests that may alter diagnostic sequencing in clinical practice. Objective: To evaluate whether receipt of IBS-Smart and/or Trio-Smart was associated with differences in diagnostic resource utilization, captured diagnostic cost, chart-level diagnostic persistence, and medication use compared with contemporaneous control patients who did not receive these tests. Methods: This retrospective two-center cohort study included 219 adults with symptoms suggestive of IBS. Patients were grouped as IBS-Smart only (n=48), Trio-Smart only (n=43), both tests (n=11), or controls receiving neither test (n=117). Costs reflected a payer-proxy perspective in 2022 US dollars and included captured diagnostic tests and gastroenterology office visits. The archived study used propensity matching and an exploratory generalized linear model (GLM) for total diagnostic cost. Results: Colonoscopy rates were 50.0% in the IBS-Smart-only cohort, 53.5% in the Trio-Smart-only cohort, 27.3% in the combined-testing cohort, and 60.7% in controls; upper endoscopy rates were 31.3%, 41.9%, 0.0%, and 48.7%, respectively. Among patients first seen in 2018 or later, mean total captured diagnostic plus office-visit cost per patient per month was $366.85 for IBS-Smart only, $382.87 for Trio-Smart only, $361.83 for both tests, and $960.39 for controls. In the archived propensity-matched GLM, IBS-Smart testing was associated with lower total diagnostic cost (coefficient -0.22; P = 0.050), corresponding to an estimated incremental savings of $526 per patient. Stable chart-level diagnosis was observed in 79.2% of IBS-Smart-only patients, 90.7% of Trio-Smart-only patients, 72.7% of patients after IBS-Smart in the combined cohort, 90.9% after Trio-Smart in the combined cohort, and 25.6% of controls. Medication counts decreased descriptively in several tested subgroups at one year; drug-class-level aggregation could not be reconstructed reliably from the archived medication file and is therefore not overstated. Conclusions: In this observational study, receipt of IBS-Smart and/or Trio-Smart was associated with lower captured resource utilization and greater chart-level diagnostic persistence than standard care alone. These findings should be interpreted as real-world associations rather than causal proof and do not replace Rome IV-based evaluation, alarm-feature triage, or guideline-recommended rule-out testing.