Comparison of RIPASA and Alvarado scores for the diagnosis of acute appendicitis.

INTRODUCTION The accuracy of the Alvarado score in diagnosing acute appendicitis in an Asian population has been disappointingly low. We prospectively compared the RIPASA score with the Alvarado score for the diagnosis of acute appendicitis. METHODS 200 consecutive patients who presented to the Accident and Emergency Department with right iliac fossa pain were recruited in the study. Both the RIPASA and Alvarado scores were derived, but decisions for appendicectomy were based on clinical judgement. Receiver operating curve (ROC), sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for both scoring systems were calculated. RESULTS Only 192 out of the 200 patients who satisfied the inclusion and exclusion criteria were included in the analysis. At the optimal cut-off threshold score of 7.5 derived from the ROC, the sensitivity, specificity, PPV, NPV and diagnostic accuracy of the RIPASA score were 98.0 percent, 81.3 percent, 85.3 percent, 97.4 percent and 91.8 percent, respectively. At the cut-off threshold score of 7.0 for the Alvarado score, the sensitivity, specificity, PPV, NPV and diagnostic accuracy were 68.3 percent, 87.9 percent, 86.3 percent, 71.4 percent and 86.5 percent, respectively. The RIPASA score correctly classified 98 percent of all patients confirmed with histological acute appendicitis to the high-probability group (RIPASA score greater than 7.5) compared with 68.3 percent with the Alvarado score (Alvarado score greater than 7.0; p-value less than 0.0001). CONCLUSION The RIPASA score at a cut-off threshold total score of 7.5 is a better diagnostic scoring system than the Alvarado score for the diagnosis of acute appendicitis in our local setting.