Diagnostic performance of a biomarker panel as a negative predictor for acute appendicitis in adult ED patients with abdominal pain.

OBJECTIVES: Evaluate the diagnostic accuracy of the APPY1TM biomarker panel, previously described for use in pediatric patients, for identifying adult ED patients with abdominal pain who are at low risk of acute appendicitis.

METHODS: This study prospectively enrolled subjects >18years of age presenting to seven U.S. emergency departments with <72hours of abdominal pain suggesting possible acute appendicitis. The APPY1 panel was performed on blood samples drawn from each patient at the time of initial evaluation and results were correlated with the final diagnosis either positive or negative for acute appendicitis.

RESULTS: 431 patients were enrolled with 422 completing all aspects of the study. The APPY1 biomarker panel exhibited a sensitivity of 97.5% (95% CI, 91.3-99.3%), a negative predictive value of 98.4% (95% CI, 94.4-99.6%), a negative likelihood ratio of 0.07 (95% CI, 0.02-0.27), with a specificity of 36.5% (95% CI, 31.6-41.8%) for acute appendicitis. The panel correctly identified 125 of 342 (36.6%) patients who did not have appendicitis with 2 (2.5%) false negatives. The CT utilization rate in this population was 72.7% (307/422). Of 307 CT scans, 232 were done for patients who did not have appendicitis and 79 (34%) of these patients were correctly identified as negative with "low risk" biomarker panel results, representing 26% (79/307) of all CT scans performed.

CONCLUSION: This biomarker panel exhibited high sensitivity and negative predictive value for acute appendicitis in this prospective adult cohort, thereby potentially reducing the dependence on CT for the evaluation of possible acute appendicitis.