Abstract
Abstract
Background
Real-world evidence on food-as-medicine programs for irritable bowel syndrome (IBS) is scarce, and single-arm evaluations overstate improvement because of regression to the mean (RTM). We estimated change in the IBS Symptom Severity Scale (IBS-SSS, 0-500) in a multi-omics personalized digital health food-as-medicine program, unadjusted and RTM-corrected.
Methods
Retrospective single-arm cohort. Of 15,933 members with a valid baseline, 2,254 had a follow-up reading and 1,683 one at least 14 days after baseline. Change at 4, 12 (primary) and 26 weeks was estimated by baseline severity stratum, unadjusted and RTM-corrected by analysis of covariance. A responder fell by at least 50 points (the minimal clinically important difference benchmark). Sensitivity analyses covered equity, inverse-probability weighting and delta-based tipping-point analyses for members without a reading in each landmark window, a negative-control stratum and medication. The association of weight loss and dietary nutrient density with symptom change was evaluated within and between members.
Results
At 12 weeks (n = 430) IBS-SSS fell by 43.88 points unadjusted (95% confidence interval [CI] – 52.44 to –35.32; p
Conclusions
IBS-SSS fell significantly among program participants, with steeper improvement in the more severe group, even after RTM correction. Improvement occurred in all subgroups, with mostly non-significant differences, though follow-up differed by subgroup and the ethnicity result depended on missing-data handling; overall estimates were robust to the assumptions evaluated. These associations from a self-selected single-arm cohort warrant replication in independent studies.