ABSTRACT

Corresponding Author:
Dr. Bismaya Kumar Rout,
Final Year Post Graduate,
Department of General Surgery,
MKCG Medical College,
Berhampur, Odisha.
E-mail: drbismayarout@gmail.com

ABSTRACT

BACKGROUND

Acute appendicitis remains the most frequent cause for emergency operations in gastrointestinal surgery. Its diagnosis relies largely on clinical assessment. Multiple scoring systems have been developed in order to identify those patients who need emergency appendicectomy of which the Alvarado score was most popular. The accuracy of Alvarado score in the diagnosis of acute appendicitis is disappointingly low in Asian population and RIPASA scoring has been designed. Here, we prospectively compared the RIPASA and Alvarado score in Indian population.

MATERIAL AND METHODS

We compared the RIPASA and Alvarado scores for diagnosis of acute appendicitis by applying them to 105 patients who presented with right iliac fossa pain during the study period. Both the RIPASA and Alvarado scores were derived, but decisions for appendicectomy was based on clinical judgment. Postoperative histopathology report was correlated with the scores. Sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV), diagnostic accuracy for RIPASA and Alvarado system was derived.

RESULT

At the optimal cut-off threshold score of 7.5 for the RIPASA score, the calculated sensitivity and specificity were 97.26% and 75% respectively compared with 68.49% and 84.37% respectively for Alvarado score at an optimal cut-off threshold of 7.0.

CONCLUSION

The RIPASA score is a better diagnostic scoring system for acute appendicitis compared to the Alvarado score with the former achieving significantly higher sensitivity, NPV and diagnostic accuracy, particularly in our population setting.

KEYWORDS

Acute Appendicitis, Appendicectomy, RIPASA, Alvarado.

INTRODUCTION

Acute appendicitis remains the most frequent cause for emergency operations in gastrointestinal surgery. Individual lifetime risk of appendicectomy due to acute appendicitis is 8.6% and 6.7% in male and female respectively.^1,2 and at the age of 25 yrs. the male:female ratio reaches its peak i.e. 3:2.¹ Its diagnosis relies largely on clinical assessment, although both ultrasound and Computed Tomography (CT) can be helpful.³ A high percentage of negative appendectomies (20%) was considered reasonable, based on the premise that delay would inevitably lead to perforation and thus increased morbidity even mortality.⁴ The cost to both the patient and the health care system of negative appendicectomy is considerable and a complication rate of up to 6.1% following removal of normal appendices was reported.⁵ Multiple scoring systems have been developed in order to identify those patients who need emergency appendicectomy thus avoiding the risk of delay as well as identifying patients

As seen in Table 06, the RIPASA score had correctly classified 71 (97.26%) patients confirmed with histological acute appendicitis (73) to the high-probability group (RIPASA score >7.5), whereas the Alvarado score had classified only 50 (68.49%) patients (Alvarado score >7.0). The 23 patients who were missed by the Alvarado score were classified wrongly into the false negative group with Alvarado score <7.0. This number was significantly higher than those wrongly classified into false negative group by the RIPASA score, i.e. 2 (RIPASA <7.5). Both the RIPASA and Alvarado scores correctly classified 24 (75%) and 27 (84.37%) patients without acute appendicitis into the true negative group with scores <7.5 and <7.0, respectively.

The mean total RIPASA scores for each group are shown in Table 06. True positive cases achieved mean total RIPASA scores of 9.22±1.34 (range 7.5–13.5), while true negative cases had mean scores of 5.04±1.51 (range 3–7). Hospital stay was significantly longer in both the true positive and false negative groups compared to the true negative group, which corresponded with the longer postoperative period observed in the former, following emergency appendicectomy.

At the optimal cut-off threshold score of 7.5 for the RIPASA score, the calculated sensitivity and specificity were 97.26% and 75% respectively compared with 68.49% and 84.37% respectively for Alvarado score at an optimal cut-off threshold of 7.0 (Table 07). The p-value for these two variables in both the scores is 0.0358, which shows there is significant association between these values. The Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for the RIPASA score were 89.87% and 92.3% respectively compared with 90.1% and 54% respectively for the Alvarado score (Table 09). Again, the p-value is 0.0173 showing significant association. The negative predictive value of RIPASA score is significantly higher than that of Alvarado

score. The diagnostic accuracy was 90.47% for the RIPASA score and 73.33% for the Alvarado score.

DISCUSSION

Acute appendicitis is one of the most common surgical emergencies and emergency appendicectomy is the commonest emergency surgery that account for one in ten of all emergency abdominal surgeries. Diagnosis of acute appendicitis largely relies on clinical assessment in many parts of the world. A quick and correct diagnosis of acute appendicitis leading to early appendicectomy and avoidance of complications arising from perforation can be difficult at times. Imaging modalities such as ultrasonography and Computed Tomography (CT) further aid in making a definite diagnosis. CT scan have been reported to have high sensitivity (94%) and specificity (95%) for diagnosing acute appendicitis.⁴ Further, assessment of C-reactive protein aids in diagnosis.³ However, the cost of such investigation is high.

The Alvarado score, which was developed in 1986 was a simple additive scoring system to help with the diagnosis of acute appendicitis.⁶ although it showed very good sensitivity and specificity when applied in a Western population, several subsequent studies have shown its limitations when applied in an Asian or Oriental population. As a result, a new scoring system called the RIPASA score was developed, which was more extensive yet simple additive scoring system consisting of 14 fixed parameters and an additional parameter (NRIC) that is unique to Asian population setting. All these 15 parameters are easily obtainable from a good clinical history, examination and investigations.

This study compared the RIPASA and Alvarado scores in our patient population who presented with RIF pain and who were suspected of acute appendicitis. The RIPASA scored considerably better than the Alvarado score in terms of correctly diagnosing patients with acute appendicitis (Sensitivity and diagnostic accuracy) as well was found to be as those who were negative for acute appendicitis (NPV).

Using the RIPASA score, 97.26% of patients who actually had acute appendicitis were correctly diagnosed and placed in the high-probability group (RIPASA score >7.5) and managed appropriately, compared to only 68.49% when using the Alvarado score on the same population sample. Thus, the Alvarado score failed to diagnose 21.9% of patients (n=23) with acute appendicitis and wrongly classified them in the low-probability group (Alvarado score <7.0). The difference in diagnostic accuracy of 17.14% between the RIPASA score and Alvarado score was significant indicating that the RIPASA score is a much better diagnostic tool for the diagnosis of acute appendicitis in our patient population, which is representative of a Southeast Asian population group.

Similarly, for patients who were classified in the low-probability group, i.e. true negative group with RIPASA score <7.5 and Alvarado score <7.0, the RIPASA score again outperformed the Alvarado score by correctly diagnosing 92.3% of patients who did not have acute appendicitis compared with the Alvarado score, which only managed to correctly diagnose 54%. In a study by Chong et al.⁹ in the year 2011 (Year of Publication), they found that at the optimal cut-off threshold score of 7.5 for the RIPASA score, the calculated sensitivity and specificity were 98.02% and 81.32% respectively compared with 68.32% and 87.91% respectively for Alvarado score at an optimal cut-off threshold of 7.0 (Table 8). The PPV and NPV for the RIPASA score were 85.34% and 97.37% respectively compared with 86.25% and 71.43% respectively for the Alvarado score. The NPV was significantly higher for the RIPASA score compared to that for the Alvarado score (p <0.0001).

The RIPASA score is a useful, rapid diagnostic tool for acute appendicitis, especially in the emergency settings as it requires only the patient’s demographics (Age, Gender and Nationality, which are all available on registration), a good clinical history (RIF pain, migration to RIF, anorexia, nausea and vomiting), clinical examination (RIF tenderness, localised guarding, rebound tenderness, Rovsing’s sign and fever) and two simple investigations (Raised white cell count and negative urine analysis performed at triage, which is defined as an absence of red and white blood cells, bacteria and nitrates).

Thus, in emergency setting, the casualty medical officer can make a quick decision upon seeing patients with RIF pain, by referring those with a RIPASA score >7.5 to the on-call surgical team for admission, while patients with a RIPASA score <7.0 can either be observed in the unit’s day ward or discharged with an early clinic review appointment. The use of a numerical score also improves the working relationships between the casualty officer and the on-call surgeon, since any patient with a RIPASA score ≥7.5 needs to be admitted.

Based on the findings of this study, our hospital

admission of patients with RIF pain during this two-year period could be reduced, resulting in substantial healthcare cost savings. With its high sensitivity (97.26%) and NPV (92.3%), the RIPASA score can also help to reduce unnecessary and expensive radiological investigations such as routine CT imaging, thus further helping to reduce annual healthcare expenditure.

Thus to conclude, the RIPASA score is a better diagnostic scoring system for acute appendicitis compared to the Alvarado score. It achieves significantly higher sensitivity, NPV and diagnostic accuracy, particularly in our population setting. It will reduce unnecessary hospital admission, healthcare cost and radiological investigation.

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