Methane Trajectory Phenotypes on Glucose Breath Testing Are Associated With Slow Colonic Transit: A Group-Based...

Intestinal methanogen overgrowth (IMO) is defined by a single binary threshold of CH₄ ≥ 10 ppm and is associated with slow transit constipation. We aimed to identify distinct breath methane trajectory phenotypes in patients with constipation and test their association with slow colonic transit.

We retrospectively analyzed 188 adults with constipation who underwent glucose breath testing and colonic transit assessment. Group-based trajectory modeling was used to classify CH₄ kinetics into phenotypes. Slow-transit prevalence and diagnostic performance were compared across phenotypes.

Sixty-nine patients (36.7%) had slow colonic transit, and 61 (32.4%) met IMO criteria. Three CH₄ phenotypes were identified: High-Producer (n = 29, 15.4%; baseline CH₄ = 31 ppm (median) with a rapid rise and sustained elevation), Low-Producer (n = 24, 12.8%; flat, CH₄ = 12 ppm), and Non-Producer (n = 135, 71.8%; flat, CH₄ = 3 ppm). Prevalence of slow transit differed across phenotypes (High-Producer: 69.0%, Low-Producer: 41.7%, Non-Producer: 28.9%; p < 0.001). High-Producer phenotype was independently associated with slow transit (aOR 5.67, 95% CI 2.22-14.50; p < 0.001). Among IMO-positive patients, slow transit was more frequent in High-Producer than others (69.0% vs. 40.6%; adjusted OR 3.98, 95% CI 1.27-13.95; p = 0.022). Compared with the IMO positives, High-Producer pattern showed higher specificity (92.4% vs. 76.5%) and positive predictive value (69.0% vs. 54.1%) for slow transit.

CH₄ trajectories identified distinct kinetic patterns in patients with chronic constipation. The High-Producer phenotype was most strongly associated with slow colonic transit and offered higher specificity than the IMO threshold.