Poor Sensitivity of a Modified Alvarado Score in Adults With Suspected Appendicitis

Study objectiveA clinical decision rule that identifies patients at low risk for appendicitis may reduce the reliance on computed tomography (CT) for diagnosis. We seek to prospectively evaluate the accuracy of a low modified Alvarado score in emergency department (ED) patients with suspected appendicitis and compare the score to clinical judgment. We hypothesize that a low modified Alvarado score will have a sufficiently high sensitivity to rule out acute appendicitis.MethodsWe performed a prospective observational study of adult patients with suspected appendicitis at 2 academic urban EDs. A low modified Alvarado score was defined as less than 4. The sensitivity and specificity were calculated with 95% confidence interval (CI) for a low modified Alvarado score, and a final diagnosis of appendicitis was confirmed by CT, laparotomy, or 7-day follow-up.ResultsTwo hundred sixty-one patients were included for analysis (mean age 35 years [range 18 to 89 years], 68% female patients, 52% white). Fifty-three patients (20%) had acute appendicitis. The modified Alvarado score test characteristics demonstrated a sensitivity and specificity of 72% (95% CI 58% to 84%) and 54% (95% CI 47% to 61%), respectively. Unstructured clinical judgment that appendicitis was either the most likely or second most likely diagnosis demonstrated a sensitivity and specificity of 93% (95% CI 82% to 98%) and 33% (95% CI 27% to 40%), respectively.ConclusionWith a sensitivity of 72%, a low modified Alvarado score is less sensitive than clinical judgment in excluding acute appendicitis.