RIPASA Score for Acute Appendicitis

About the original study

The RIPASA score was designed by Chong et al. following the 2010 study as a scoring system for diagnosing appendicitis, more sensitive in predictive ability than the Alvarado score in Middle Eastern and Asian populations.

Clinical data was collected retrospectively from a cohort of 312 patients who had undergone an emergency appendicectomy.

15 parameters were generated and a score of 0.5, 1.0 or 2.0 was allocated to each:

Patient’s Demographic information: Gender and Age;

Symptoms: Right iliac fossa (RIF) pain, Migration of pain to right lower quadrant (RLQ), Anorexia, Nausea & vomiting, Duration of symptoms;

Signs: Right iliac fossa (RIF) tenderness, Right iliac fossa (RIF) guarding, Rebound tenderness, Rovsing’s Sign, Fever (>37 °C);

Investigations: Raised WCC, Negative urinalysis;

Additional criterion: Foreign national – as the score is mainly to be used for screening Asian populations and in Singapore, where it was designed, foreign national criterion was found to have some predictive capacity and introduced in the score.

The optimal cut-off threshold score from the receiver operating curve (ROC) was 7.5 with a sensitivity of 88%, a specificity of 67%, a positive predictive value of 93% and a negative predictive value of 53%. The negative appendicectomy rate was found to decrease from 16.3 to 6.9%.

Subsequent validation studies

In the validation study conducted by Butt et al. on a cohort of 267 patients (156 male, 111 female), the score was employed and diagnosis was made by routine sonography of abdomen. The following psychometric properties of the RIPASA were extracted:

■ Sensitivity: 96.7%

■ Specificity: 93.0%

■ Diagnostic accuracy: 95.1%

■ Positive predictive value: 94.8%

■ Negative predictive value was 95.54%.

In a comparison study conducted by Frountzas et al. between the RIPASA and Alvarado score, data from twelve studies was meta-analysed (total cohort of 2161 patients).

The sensitivity of RIPASA score was 94% (95% CI, 92%-95%) and the specificity was 55% (95% CI, 51%-55%). The sensitivity of Alvarado score was 69% (95% CI, 67%-71%) and the specificity was 77% (95% CI, 74%-80%).

The analysis concluded the RIPASA scoring system is more sensitive than Alvarado scoring but has lower specificity, thus needing supplementary means for accurate diagnosis. Both scores were recommended for aiding clinical gestalt in acute appendicitis presentations.

References

Original reference

Chong CF, Adi MI, Thien A, Suyoi A, Mackie AJ, Tin AS, Tripathi S, Jaman NH, Tan KK, Kok KY, Mathew VV, Paw O, Chua HB, Yapp SK. Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis. Singapore Med J. 2010; 51(3):220-5.

Validation

Butt MQ, Chatha SS, Ghumman AQ, Farooq M. RIPASA score: a new diagnostic score for diagnosis of acute appendicitis. J Coll Physicians Surg Pak. 2014; 24(12):894-7.

Other references

Chong CF, Thien A, Mackie AJ, Tin AS, Tripathi S, Ahmad MA, Tan LT, Ang SH, Telisinghe PU. Comparison of RIPASA and Alvarado scores for the diagnosis of acute appendicitis. Singapore Med J. 2011; 52(5):340-5.

Frountzas M, Stergios K, Kopsini D, Schizas D, Kontzoglou K, Toutouzas K. Alvarado or RIPASA score for diagnosis of acute appendicitis? A meta-analysis of randomized trials. Int J Surg. 2018; 56:307-314.