COST-EFFECTIVENESS OF INITIAL MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY VERSUS A RISK STRATIFICATION ALGORITHM FOR MANAGEMENT OF SUSPECTED CHOLEDOCHOLITHIASIS

Purpose: For symptomatic gallstones, a condition affecting 10-15% of adults, a number of diagnostic strategies have been proposed with conflicting recommendations for non-invasive evaluation using magnetic resonance cholangiopancreatography (MRCP) for suspected common duct (CD) stones. Our purpose was to analyze the cost-effectiveness of the American Society for Gastrointestinal Endoscopy (ASGE) risk stratification guidelines for triage to endoscopy- an invasive procedure- or MRCP, versus uniform MRCP for all patients with possible CD stones.

Methods: A decision-analytic model was constructed to compare cost and effectiveness of three diagnostic strategies for suspected CD stones: non-contrast MRCP for all patients, contrast-enhanced MRCP for all patients, or application of ASGE guidelines for triage (contrast-enhanced MRCP for intermediate risk, endoscopic retrograde cholangiopancreatography (ERCP) for high risk, and no test for low risk of CD stones); analysis was performed from a societal perspective over both one-year and lifetime horizons, given the short-term effects of biliary stone treatment and longer impact of possible malignant diagnoses. The model accounted for benign or malignant causes of biliary obstruction and procedural complications, informed by the literature. Cost information was based on Medicare reimbursements. We used sensitivity analysis to assess effects of parameter variability on model results.

Results: In the base case of 65-year-old men, ASGE guidelines were less costly than initial MRCP-based strategies (1 year: $3577 vs. $3645, $3767 respectively; lifetime: $175,728-175,949). Quality-adjusted life years were similar across strategies, minimally higher with MRCP (10.467-10.472 QALY). Uniform use of non-contrast MRCP had a lifetime ICER of $50,757 per quality-adjusted life year. Treatment selection based on ASGE guidelines provided the highest net monetary benefit only within one year ($181 more than initial non-contrast MRCP). Results were most sensitive to patient utilities related to gallstone-related pain, probability of major procedural complication, and cost of endoscopic procedures. Initial non-contrast MRCP became the most cost-effective strategy when it cost $50 with ≥95% sensitivity and specificity, or with probability of major endoscopic complication ≥0.4.

Conclusion: ASGE risk stratification for symptomatic gallstone disease offers a cost-effective means of selecting a management strategy, while initial MRCP is not cost-effective unless sensitivity and specificity are excellent at very low cost. Patients at high risk of endoscopic procedural complications or in severe pain may benefit from initial MRCP regardless of ASGE classification, however.