Acute appendicitis is a common and urgent surgical condition, with a lifetime risk of about 7%. It remains one of the most frequent reasons for emergency abdominal surgery worldwide, accounting for approximately 10% of all such operations. Accurate diagnosis is essential to minimize the risk of unnecessary procedures and avoid complications such as perforation, which significantly increases morbidity and mortality. The traditional diagnosis of appendicitis is primarily clinical, based on a combination of patient history, physical examination, and laboratory findings. However, the diagnosis can often be ambiguous, particularly in atypical cases, and may result in a negative appendicectomy if misdiagnosed.

To aid in the diagnostic process, various scoring systems have been developed. Among the most commonly used are the Alvarado score and its modified version, which are based on clinical signs, symptoms, and laboratory tests. These scores have been widely validated in Western populations and are effective in many clinical settings. However, they have shown limitations in certain populations, particularly in Middle Eastern and Asian countries where appendicitis often presents with different symptom patterns, or where access to advanced imaging technologies is limited[1][2].

In response to these challenges, the RIPASA (Raja Isteri Penigiran Anak Saleha) scoring system was developed by Dr. William Chong in 2010 specifically for use in Asian populations. RIPASA was designed to address the diagnostic challenges in regions where healthcare settings may not have access to modern radiographic imaging tools such as computed tomography (CT) scans and ultrasound. This scoring system includes 14 clinical parameters, offering a comprehensive approach to diagnosis based on physical signs and symptoms. Previous studies have shown that RIPASA provides high sensitivity (97.5%) and specificity (81.8%) for diagnosing acute appendicitis, with an overall diagnostic accuracy of approximately 91.8%[3][4].

While RIPASA has been shown to be superior to other diagnostic methods like the Alvarado score in several studies, further validation across diverse clinical settings is necessary. In particular, its accuracy in different populations, including those in regions with less access to radiological imaging, needs to be established. This paper aims to evaluate the RIPASA scoring system's effectiveness in diagnosing acute appendicitis in a tertiary care hospital setting, comparing its performance against histopathologically confirmed appendicitis as the gold standard.

This study aimed to validate the diagnostic accuracy of the RIPASA scoring system in diagnosing acute appendicitis at a tertiary care hospital. The following outlines the study design, patient inclusion criteria, data collection methods, statistical analysis, and ethical considerations based on the procedures followed in the thesis.

Study Design

This was a prospective observational study conducted at Yenepoya Medical College Hospital, focusing on patients presenting with right iliac fossa (RIF) pain suspected of acute appendicitis. The study was conducted between August 2022 and July 2024. Patients included in the study were evaluated using the RIPASA scoring system, and the results were compared with histopathologically confirmed diagnoses of acute appendicitis, serving as the gold standard.

Study Population

Inclusion Criteria:

• Adult patients aged 18 years or older.
• Patients presenting with right iliac fossa pain and suspected of having acute appendicitis.
• Patients who were willing to participate in the study and signed an informed consent.

Exclusion Criteria:

• Patients with a history of prior appendicectomy.
• Patients with chronic abdominal conditions or conditions that affect the diagnosis of appendicitis.
• Patients not willing to undergo surgery or those who refused participation in the study.
• Patients who had undergone abdominal surgery within the last 90 days.
• Pregnant women.
• Patients with appendicular mass or abscess.

Data Collection

Patient History and Physical Examination:

• A detailed history was taken from the patients, including the onset, duration, and characteristics of abdominal pain, associated symptoms (nausea, vomiting, anorexia), and any relevant medical history.
• Physical examination focused on localized tenderness, rebound tenderness, guarding, and signs such as Rovsing’s sign, psoas sign, and obturator sign.
• Vital signs (temperature, pulse) were recorded.

Laboratory Investigations:

• Blood tests, including a complete blood count (CBC), were performed to assess the white blood cell (WBC) count, as an elevated WBC count is an important marker for appendicitis.
• Urinalysis was conducted to rule out urinary tract infections or other potential abdominal pathologies that could mimic appendicitis.

Application of the RIPASA Scoring System:

• The RIPASA scoring system was applied based on clinical signs and symptoms, which included parameters such as sex, age, duration of symptoms, anorexia, nausea, vomiting, fever, RIF tenderness, rebound tenderness, Rovsing’s sign, guarding, WBC count, and other factors.
• The scoring system consists of 14 parameters, and based on the scores, patients were categorized into low, moderate, or high probability groups for acute appendicitis. The cutoff score used to define high probability of appendicitis was ≥7.5.

Histopathological Diagnosis:

• All patients underwent appendicectomy as part of their clinical treatment. The removed appendix was sent for histopathological examination to confirm the diagnosis of acute appendicitis.
• Histopathological findings were categorized into types such as acute appendicitis, acute appendicitis with lymphoid hyperplasia, and other types, depending on the severity and characteristics of the inflammation observed.

Statistical Analysis

Descriptive Statistics:

• Demographic characteristics, clinical features, RIPASA scores, and histopathological results were analyzed using descriptive statistics such as frequencies, percentages, means, and standard deviations.

Sensitivity, Specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV):

• Sensitivity, specificity, PPV, and NPV of the RIPASA scoring system were calculated by comparing its diagnostic results with histopathologically confirmed appendicitis.
• The cut-off value of RIPASA was analyzed for its diagnostic performance.

Receiver Operating Characteristic (ROC) Curve Analysis:

• ROC analysis was performed to evaluate the diagnostic accuracy of the RIPASA score, determining the optimal cutoff for diagnosing acute appendicitis. The area under the curve (AUC) was used to assess the overall diagnostic accuracy of the RIPASA score.

Statistical Software:

• All statistical analyses were performed using [software name] (e.g., SPSS version 25, R software). A p-value of less than 0.05 was considered statistically significant for this study.

Ethical Considerations

Ethical Approval:

• The study was approved by the institutional review board/ethics committee at Yenepoya medical college hospital. It was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki.

Informed Consent:

• Written informed consent was obtained from all participants prior to inclusion in the study. The consent form included detailed information regarding the study’s objectives, procedures, and potential risks. Patients were assured that their participation was voluntary and that their data would be kept confidential.

Confidentiality:

• All personal information related to the patients was kept confidential. Data were anonymized and stored securely, with access restricted to authorized personnel only. The results of the study were reported in aggregate form, ensuring that no personal identifying information was disclosed.

This section presents the findings from the application of the RIPASA scoring system in diagnosing acute appendicitis. The results include descriptive statistics, the comparison of RIPASA scores with histopathological findings, and the diagnostic performance (sensitivity, specificity, PPV, NPV) of the RIPASA scoring system. Additionally, tables and graphs are used to visually represent the key data and justify the title, "Validation of RIPASA Scoring System in Diagnosing Acute Appendicitis."

1. Demographic and Clinical Characteristics

The study included 162 patients, of which 103 (63.6%) were male, and 59 (36.4%) were female. The average age of the participants was 29.98 years (SD = 10.23), with a range from 18 to 58 years. The clinical characteristics observed were:

• Pain migration to the right iliac fossa (RIF): 100 patients (61.7%) reported pain migration to RIF, while 62 (38.3%) did not.
• Presence of Anorexia: 68 patients (42%) experienced anorexia.
• Nausea and Vomiting: 107 patients (66%) presented with nausea and vomiting.
• Guarding: 18 patients (11.1%) exhibited guarding.
• Rebound Tenderness: 109 patients (67.3%) had rebound tenderness.
• Rovsing’s Sign: 66 patients (40.7%) were positive for Rovsing’s sign.
• Fever: 47 patients (29%) presented with fever.

2. RIPASA Scoring and Histopathological Diagnosis

The RIPASA scores for patients ranged from 3.0 to 12.5, with a mean score of 8.78 (SD = 2.29). A cutoff score of 7.5 was used to categorize patients into high and low-risk groups for appendicitis. Of the 162 patients, 119 patients (73.5%) had a score of 7.5 or higher, while 43 patients (26.5%) had a score below 7.5.

The histopathological results showed that:

• 67 patients (41.4%) had acute appendicitis.
• 10 patients (6.2%) had acute appendicitis with lymphoid hyperplasia.
• 9 patients (5.6%) had acute appendicitis with peri-appendicitis.
• 14 patients (8.6%) had subacute appendicitis.
• Other diagnostic categories were resolving appendicitis or chronic appendicitis.

The RIPASA scores were correlated with these histopathological findings to evaluate diagnostic accuracy.

3. Diagnostic Performance of RIPASA Score

The diagnostic performance of the RIPASA scoring system was evaluated by comparing the scores with the histopathologically confirmed diagnoses of appendicitis. The performance metrics (sensitivity, specificity, PPV, NPV) were calculated as follows:

• Sensitivity:46% (95% CI, 84.5% to 92.5%)
• Specificity:7% (95% CI, 59.2% to 74.2%)
• Positive Predictive Value (PPV): 93% (95% CI, 89.7% to 96.4%)
• Negative Predictive Value (NPV): 53% (95% CI, 47.1% to 59.0%)
• Diagnostic Accuracy:5%

These results demonstrate that the RIPASA score is highly sensitive in detecting acute appendicitis, but its specificity is moderate, which may lead to some false positives.

4. ROC Curve Analysis

An ROC curve was plotted to determine the optimal cutoff for RIPASA scores in diagnosing acute appendicitis. The area under the curve (AUC) was 0.88, indicating a good overall diagnostic performance of the RIPASA score in distinguishing between appendicitis and non-appendicitis cases.

Table 1: Distribution of Demographic and Clinical Characteristics

Table 2: Histopathological Findings

Table 3: RIPASA Score Performance

The results of this study validate the use of the RIPASA scoring system in diagnosing acute appendicitis, demonstrating its high sensitivity (88.46%) and positive predictive value (93%) for detecting appendicitis. However, the specificity of 66.7% suggests that while the RIPASA score is excellent at correctly identifying patients with appendicitis, it may also result in some false positives. These findings are consistent with other studies that have highlighted the superiority of RIPASA over traditional scoring systems such as the Alvarado score, especially in Asian populations where clinical presentations may vary compared to Western populations.

The high sensitivity observed in this study is in line with previous research, which has reported that RIPASA performs exceptionally well in identifying patients with acute appendicitis, reducing the risk of negative appendectomy. Chong et al. (2010) [4]reported a sensitivity of 97.5% for the RIPASA score, which was significantly higher than that of the Alvarado score, particularly in Asian populations where clinical features may differ . Similarly, Butt et al. (2014) [7]confirmed that RIPASA is highly sensitive in diagnosing appendicitis, making it an important tool for clinicians in settings where radiological diagnostics are not readily available. Moreover, Malik et al. (2017) [5] also reported that RIPASA is highly sensitive in diagnosing acute appendicitis, further supporting its applicability in clinical practice.

The specificity of 66.7%, although lower than the sensitivity, is comparable to that found in other studies. For instance, a study by Shuaib et al. (2017)[3] reported a specificity of 71.5% for RIPASA, emphasizing that while the score is highly accurate at detecting positive cases, it may also misclassify some patients as having appendicitis when they do not . This highlights the importance of using the RIPASA score in conjunction with clinical judgment, as certain non-appendicitis conditions can mimic the symptoms of acute appendicitis.

The positive predictive value (PPV) of 93% observed in this study suggests that when the RIPASA score indicates a high probability of appendicitis, the likelihood of the diagnosis being correct is very high. This finding supports the utility of RIPASA as a highly reliable screening tool for patients presenting with right iliac fossa pain. The negative predictive value (NPV) of 53%, on the other hand, suggests that a low RIPASA score does not rule out the diagnosis of acute appendicitis as effectively. This is consistent with the findings of Chisthi et al. (2020), [1,9] who noted that the NPV of RIPASA is lower compared to its sensitivity and PPV, emphasizing that a negative RIPASA score does not always preclude the diagnosis of appendicitis, particularly in cases with atypical presentations .

The Receiver Operating Characteristic (ROC) curve analysis further strengthens the findings, with an area under the curve (AUC) of 0.88, indicating that the RIPASA score has a good overall diagnostic performance. Previous studies have also confirmed the strong diagnostic ability of RIPASA, with an AUC ranging from 0.87 to 0.92 in various clinical settings. The optimal cutoff score of ≥7.5, used in this study, effectively identifies patients at high risk for acute appendicitis, further corroborating its role in clinical practice as an effective diagnostic tool [8].

In conclusion, the RIPASA scoring system demonstrates excellent sensitivity and diagnostic accuracy for diagnosing acute appendicitis, particularly in settings with limited access to advanced imaging technologies. While its specificity is moderate, the high PPV makes it a useful tool in identifying patients who are likely to have appendicitis, thus guiding clinical decisions for surgery. This study supports the growing body of evidence that RIPASA is a reliable and practical diagnostic tool for acute appendicitis, especially in regions where advanced imaging is not readily available. However, the moderate specificity and NPV highlight the need for additional diagnostic tools or clinical judgment to confirm the diagnosis in certain cases. Future studies should aim to further refine the RIPASA score’s performance across diverse patient populations and in conjunction with other diagnostic modalities, including imaging.

This study confirms that the RIPASA scoring system is a reliable and effective tool for diagnosing acute appendicitis, particularly in clinical settings with limited access to advanced radiological imaging. The high sensitivity (88.46%) and positive predictive value (93%) of the RIPASA score demonstrate its excellent ability to identify patients with acute appendicitis, reducing the risk of negative appendectomy. While the moderate specificity (66.7%) and negative predictive value (53%) highlight some limitations, these findings are consistent with other studies that have shown RIPASA's strong performance in Asian populations where appendicitis may present atypically and radiographic imaging is often unavailable.

The ROC curve analysis further supports RIPASA’s diagnostic accuracy, with an area under the curve (AUC) of 0.88, indicating that it is a robust diagnostic tool. The study also emphasizes the importance of using RIPASA in conjunction with clinical judgment to avoid false positives, particularly in patients presenting with non-specific abdominal pain or other conditions that mimic appendicitis.

In conclusion, RIPASA offers significant advantages in settings with limited access to imaging modalities, making it an invaluable tool in diagnosing acute appendicitis, especially in resource-constrained environments. However, its moderate specificity calls for further research to refine the scoring system, explore potential modifications, and combine it with additional diagnostic methods to enhance its performance. Future studies should focus on further validating RIPASA across diverse patient populations and in conjunction with other diagnostic tools such as imaging techniques to optimize diagnostic accuracy and clinical decision-making in suspected cases of acute appendicitis.

1. Chisthi MM, Surendran A, Narayanan JT. RIPASA and AIR scoring systems are superior to Alvarado scoring in acute appendicitis: Diagnostic accuracy study. ScienceDirect. Available from: https://www.sciencedirect.com/science/article/pii/S2049080120303344.
2. Akbar I, Shehzad JA, Ali S. Diagnostic Accuracy Of Ripasa Score. Academia.edu. Available from: https://www.academia.edu/download/89580299/2714.pdf.
3. Shuaib A, Shuaib A, Fakhra Z, Marafi B. Evaluation of modified Alvarado scoring system and RIPASA scoring system as diagnostic tools of acute appendicitis. PubMed Central. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5675968/.
4. Chong CF, Thien A, Mackie AJA, Tin AS. Comparison of RIPASA and Alvarado scores for the diagnosis of acute appendicitis. ResearchGate. Available from: https://www.researchgate.net/profile/Pemasiri-Telisinghe/publication/51185031_Comparison_of_RIPASA_and_Alvarado_scores_for_the_diagnosis_of_acute_appendicitis/links/0deec531a731b937a3000000/Comparison-of-RIPASA-and-Alvarado-scores-for-the-diagnosis-of-acute-appendicitis.pdf.
5. Malik MU, Connelly TM, Awan F, Pretorius F. The RIPASA score is sensitive and specific for the diagnosis of acute appendicitis in a western population. SpringerLink. Available from: https://link.springer.com/article/10.1007/s00384-016-2713-4.
6. Chong CF, Adi MIW, Thien A, Suyoi A. Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis. Academia.edu. Available from: https://www.academia.edu/download/68541356/Development_of_the_RIPASA_score_A_new_ap20210803-28554-1cad7of.pdf.
7. Butt MQ, Chatha SS, Ghumman AQ. RIPASA score: A new diagnostic score for diagnosis of acute appendicitis. ResearchGate. Available from: https://www.researchgate.net/profile/Sohail-Chatha/publication/269768825_RIPASA_Score_A_New_Diagnostic_Score_for_Diagnosis_of_Acute_Appendicitis/links/5cb72b214585156cd79dfcb7/RIPASA-Score-A-New-Diagnostic-Score-for-Diagnosis-of-Acute-Appendicitis.pdf.
8. Gan DEY, Nik Mahmood NRK, Chuah JA. Performance and diagnostic accuracy of scoring systems in adult patients with suspected appendicitis. SpringerLink. Available from: https://link.springer.com/article/10.1007/s00423-023-02991-5.
9. Chong CF, Thien A, Mackie AJA, Tin AS. Evaluation of the RIPASA Score: a new scoring system for the diagnosis of acute appendicitis. ResearchGate. Available from: https://www.researchgate.net/profile/William-Chong-5/publication/47716251_Evaluation_of_the_RIPASA_Score_A_new_appendicitis_scoring_system_for_the_diagnosis_of_acute_appendicitis/links/54d8b2190cf25013d03eb378/Evaluation-of-the-RIPASA-Score-A-new-appendicitis-scoring-system-for-the-diagnosis-of-acute-appendicitis.pdf?_sg%5B0%5D=started_experiment_milestone&origin=journalDetail&_rtd=e30%3D.