Abstract Background Biomarker-guided monitoring has the potential to improve patient outcomes and healthcare efficiency in inflammatory bowel disease (IBD) care. Fecal calprotectin is a noninvasive stool biomarker with high correlation with endoscopic activity. Few population-based studies have examined the real-world impact of fecal calprotectin monitoring on colonoscopy utilization. We conducted a group-aligned interrupted time series analysis to assess the effect of fecal calprotectin adoption on colonoscopy use. Methods We performed a group-aligned interrupted time series analysis across Veterans Health Administration (VHA) medical centers to evaluate the impact of fecal calprotectin adoption on colonoscopy use in patients with IBD. Using VHA data from 1/2009 to 1/2020, we identified fecal calprotectin tests and colonoscopies performed in patients with IBD. For each qualifying facility, monthly fecal calprotectin and colonoscopy counts were aggregated and normalized per 100 active IBD patient per month. The index month was defined as the first month with =2 fecal calprotectin tests, followed by sustained use of average =2 tests/mo post index. Analyses were restricted to the 36 months before and after implementation. We used segmented regression with autoregressive error correction to estimate changes in level and slope of colonoscopy rates. Sensitivity analyses were conducted stratifying by IBD subtype, age category, and tertiles of fecal calprotectin testing rates. Results Across 44 VHA medical centers, fecal calprotectin adoption increased steadily over the study period. Over the study period 6,051 calprotectin tests and 30,392 colonoscopies were included. Following adoption, fecal calprotectin testing rose sharply (level change p = 0.02; slope change p 0.001). In contrast, colonoscopy use remained stable throughout the observation window. Neither the immediate level change (p = 0.22) nor the post-implementation trend change (p = 0.37) in colonoscopy rates was significant. Sensitivity analyses stratified by age, IBD subtype, and pre-adoption testing tertile showed no meaningful or sustained reductions in colonoscopy use in any subgroup. Adults 40 years old displayed a transient decline in colonoscopy rates at implementation that reversed in the post-period. Conclusion We found no significant change in colonoscopy utilization among patients with IBD. These findings may reflect limited calprotectin uptake, insufficient clinician confidence in fecal calprotectin performance, or an entrenched reliance on colonoscopy for disease assessment. Further work is needed to understand barriers to biomarker-guided care and to identify strategies that more effectively translate noninvasive monitoring into meaningful changes in clinical practice. Conflict of interest: Dr. Sninsky, Jared: No conflict of interest Sansgiry, Shubhada: No conflict of interest Taylor, Thomas: No conflict of interest Bali, Aman: No conflict of interest Hou, Jason K.: JH has received research funding from Redhill Biosciences, Janssen, AbbVie, Celgene, Genentech, Bristol Myer Squib, Eli-Lilly, Lycera, and Pfizer Inc.
Sninsky et al. (Thu,) studied this question.