Microsimulation Model to Determine the Cost-Effectiveness of Treat-to-Target Strategies for Ulcerative Colitis

Background & Aims: Little is known about the cost effectiveness of endoscopy or biomarker-based treat to target monitoring of patients with ulcerative colitis (UC). Methods: We used a microsimulation model to identify the most cost effective treat to target monitoring strategy for patients with UC staring therapy with biologics or small molecule inhibitors. We assessed symptoms (rectal bleeding) alone, a combination of symptoms and a biomarker (fecal calprotectin), and endoscopy. Transition probabilities, costs, and quality-adjusted life year (QALY) estimates were derived from published estimates. The microsimulation model tracked an individual patient's disease course and treatment exposures to modify downstream treatment effectiveness, probabilities, and disease outcomes. The primary analysis included 100,000 individuals over 5 years with a willingness to pay threshold of $100,000/QALY. Probabilistic sensitivity analyses were performed with 500 samples and 250 trials, in addition to multiple 1-, 2-, and 3-way microsimulation sensitivity analyses. Results: A total of 32 treatment sequencing algorithms were modeled alongside 3 disease monitoring strategies within a treat to target approach for UC. Combination symptom and biomarker-based monitoring resulted in the highest QALY estimate among all the treatment sequencing algorithms. However, monitoring disease activity with symptoms alone was the most cost-effective strategy in 86% of scenarios, followed by combination symptom and biomarker monitoring in 9%, and endoscopy monitoring in 5%. Results were sensitive to treatment costs, patient willingness to consider colectomy as a treatment option, and endoscopy costs. Endoscopy-based monitoring was favored when treatment costs were high and patients were unwilling to undergo colectomy. Conclusions: The combination symptom and biomarker-based monitoring resulted in the highest QALY estimate. However, symptom-based monitoring is the most cost-effective approach to implementing treat to target monitoring for patients with UC receiving biologics and small molecule inhibitors.