Validation of the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) scoring system for the diagnosis of acute appendicitis among Ethiopian patients: a multi-institutional observational study.

Background: Acute appendicitis is the most common surgical emergency in Ethiopian clinical practice. Although a multitude of scoring systems have been used in clinical practice, none have been universally validated. The purpose of this study was to validate the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) scoring system in the Ethiopian context.

Methods: A total of 315 consecutive patients who presented with a presumptive diagnosis of acute appendicitis and were planned to undergo appendectomy were studied. All the studied patients had diagnostic sonography and underwent the RIPASA scoring system. The sensitivity, specificity, positive predictive value, and negative predictive value of RIPASA and ultrasound results with intraoperative gross examinations.

Results: The mean age of the participants was 27.4 ± 11.5 years, with a male-to-female ratio of 1.6:1. The concordance between ultrasound and RIPASA for the diagnosis of acute appendicitis was 93.6%. The sensitivity, specificity, positive predictive value, and negative predictive value of RIPASA were 96.2%, 30.8%, 93.9%, and 42.1%, respectively. Similarly, the sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound were 95.3%, 27.8%, 95.6%, and 26.3%, respectively. White cell count and RIPASA scores were weakly correlated with intraoperative stages of acute appendicitis, r(313) = 0.18, p = 0.001, and r(313) = 0.129, p = 0.022, respectively. The rate of a negative appendectomy was 6%.

Conclusion: RIPASA and ultrasound had equivalent performance in the diagnosis of acute appendicitis. In both cases, the rate of negative appendectomy was low enough to validate RIPASA for clinical practice in low-income institutions where sonographic diagnosis by a conventionally trained radiologist is not available.