Tu1089 Optimal Imaging for the Diagnosis of Acute Appendicitis in Adults, Children and Pregnant Women: A Decision Analysis

Abstract

Background: Accurate and timely diagnosis of acute appendicitis can reduce mortality, improve clinical outcomes, and optimize resource utilization. Our aim was to compare computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) for the diagnosis of acute appendicitis in adults, children and pregnant women. Methods: For a hypothetical cohort of 10,000 patients, we constructed a decision analysis model to examine 3 imaging modalities for the diagnosis of acute appendicitis in adults, children and pregnant women presenting with abdominal pain. Imaging sensitivity and specificity were based on an AHRQ systematic review and meta-analysis of over 800 studies, e.g., sensitivity of CT (96%), MRI (91%) and US (83%) and specificity of CT (96%), MRI (86%) and US (89%) in adults. Prevalence and complication rates (perforation at presentation and after delayed diagnosis and mortality) were based on published estimates. Outcomes included overall surgery rate (initial+delayed), delayed surgery (false negatives), unnecessary surgery (false positives), perforated appendicitis (initial+delayed) and mortality. Results: In adults with a 25% risk of appendicitis, CT was the best strategy with 750 and 525 fewer total surgeries and unnecessary surgeries, 124 and 325 fewer delayed surgeries, 45 and 117 fewer perforations, and 9 and 22 more lives saved per 10,000 patients compared to MRI and US, respectively (Table 1). For children with a 10% risk of appendicitis, MRI performed best with 720 and 630 fewer total surgeries and unnecessary surgeries, 40 and 110 fewer delayed surgeries, 20 and 55 fewer perforations, and 1 and 1 more life saved per 10,000 patients compared to CT and US, respectively. For pregnant women with 30% risk of appendicitis, MRI was best with no fewer surgeries or unnecessary surgeries but with 40 and 110 fewer perforations, and 6 and 48 more lives saved per 10,000 patients compared to CT and US, respectively. In one-way sensitivity analysis of the 95% CI for sensitivity and specificity, the optimal strategies above remained preferred except when 1) the sensitivity of MRI increased, making it more favorable in adults, 2) the sensitivity and specificity of MRI fell in children and CT became favored and 3) the sensitivity of MRI fell and the sensitivity of CT increased in pregnant women and CT became favored. Conclusion: The results suggest that imaging should be tailored to the type of patient presenting with suspected acute appendicitis and that optimal imaging testing would reduce morbidity and mortality while reducing resource utilization. The results were sensitive to variation in test sensitivity and specificity, so patient care should consider local test performance. Future analyses should incorporate quality of life adjustments, costs and long-term effects of radiation, non-diagnostic imaging results, and serial imaging. Outcomes for 10,000 Patients with Suspected Acute Appendicitis