Diagnostic Accuracy of RIPASA and Modified Alvarado Scoring Systems in the Diagnosis of Acute Appendicitis: A Prospective Comparative Study

Abstract

Background: Acute appendicitis is one of the most common surgical emergencies. Early diagnosis remains challenging because clinical presentation often overlaps with other causes of right iliac fossa pain. Clinical scoring systems such as the Modified Alvarado Score (MAS) and the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score have been developed to improve diagnostic accuracy. This study compared the diagnostic performance of the two scoring systems using histopathology as the reference standard. Methods: A prospective observational study was conducted in the Department of General Surgery of a tertiary care teaching hospital between October 2016 and October 2018. One hundred consecutive patients aged >15 years with suspected acute appendicitis were included. RIPASA and Modified Alvarado scores were calculated before surgery. Histopathological examination of the appendectomy specimen served as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic accuracy, and receiver operating characteristic (ROC) curve analysis were performed. Results: Histopathology confirmed acute appendicitis in 75% of patients. The RIPASA score demonstrated higher sensitivity (89.3% vs. 58.7%), higher PPV (94.4% vs. 93.6%), higher NPV (72.4% vs. 41.5%), and greater overall diagnostic accuracy (88% vs. 66%) than the Modified Alvarado score. ROC analysis showed superior discriminatory ability for RIPASA (AUC 0.891) compared with Modified Alvarado (AUC 0.702). Conclusion: The RIPASA score demonstrated superior diagnostic performance compared with the Modified Alvarado score in patients with suspected acute appendicitis. Its higher sensitivity and overall accuracy suggest that it may be a more reliable clinical tool, particularly in Asian populations.