Acute appendicitis is the predominant aetiology of an acute abdomen necessitating surgical intervention, with a lifetime risk of approximately 7%.1 Acute appendicitis is a prevalent surgical emergency frequently seen by junior doctors during on-call responsibilities. Emergency appendicectomy constitutes roughly 10% of all emergency abdominal surgery.2 Acute appendicitis poses a challenging diagnosis, especially in the young, the elderly, and females of reproductive age, due to the potential for various genitourinary and gynecological inflammatory disorders to exhibit similar signs and symptoms. A postponement in conducting an appendicectomy for diagnostic precision elevates the likelihood of appendiceal perforation and infection, hence heightening the danger of morbidity and fatality.3 Acute appendicitis may sometimes present with atypical presentations, and the diagnosis becomes more challenging when the symptoms overlap with other disease conditions.8 The diagnosis relies on patient history, clinical assessment, and laboratory tests. A delay in the treatment of acute appendicitis, even by a few hours, can lead to significant consequences. Timely diagnosis and care of acute appendicitis in the young, elderly, and reproductive-age females are crucial to prevent complications. Diagnostic accuracy can be enhanced through the utilization of computed tomography imaging.4 CT imaging is expensive and may not be universally accessible. Organizing these diagnostic modalities may result in further delays in diagnosis and operation. Diverse grading systems have been established to assist in the diagnosis of acute appendicitis. The Alvarado score and the modified Alvarado score are the primary assessment tools utilized. The sensitivity and specificity of the Alvarado score vary between 53% and 88%, but the modified Alvarado scores range from 75% to 80%.5 Western-developed Alvarado and modified Alvarado scoring systems have low sensitivity and specificity for people with varied diets and cultures. For Southeast Asian populations, the Raja Isteri Pengiran Anak Saleha Appendicitis Scoring System (RIPASA) has 88% sensitivity and 67% specificity.6 RIPASA is a novel grading technique for acute appendicitis diagnosis. It has 14 clinical variables and greater sensitivity, specificity, and diagnostic accuracy than the Alvarado scoring system, especially in Asians.4 In the present study, we were validating the sensitivity, specificity, and clinical accuracy of the RIPASA scoring system compared to the modified Alvarado scoring system in the diagnosis of acute appendicitis, and their specificity, sensitivity, positive predictive value, and negative predictive value in relation to ultrasound abdomen, pelvis, and also to the histopathology report.

Study setting and design: This is a prospective observational study conducted in the Department of General Surgery at the Sri Venkateswara Institute of Medical Sciences, Tirupati. A total of 70 Patients with a diagnosis of acute appendicitis were included during the period 2021 to 2022. Inclusion criteria: Patients exhibiting symptoms indicative of acute appendicitis were screened for inclusion. All adult patients (18 years or older) were included based on clinical suspicion of acute appendicitis in the study. Exclusion criteria: Exclusion criteria included patients under 18 and over 60, pregnant women, and patients with Diffuse abdominal discomfort. Patients having appendicular masses or abscesses. Appendicular perforation patients. Patients with inconclusive acute appendicitis diagnoses on clinical examination and abdominal ultrasound. Unwilling study participants. Unsuitable surgery patients. Patients refusing appendicectomy. Abdominal TB patients. Informed written consent was obtained from all individuals prior to their inclusion in the study. Study Procedure: All patients had a comprehensive assessment for abdominal pain and the duration of their symptoms. An extensive case history was recorded, and all aspects of the clinical examination were documented. Following a thorough clinical assessment, patients underwent relevant investigations, including urine analysis for microscopy, haematological and biochemical tests, as well as abdominal ultrasonography. Physical examination was focused on RIF tenderness, RIF guarding, rebound tenderness, and Rovsing’s sign. Laboratory investigations that were done in these cases are complete blood count using “Haematology blood cell counter (BC 5300 Mindary)”, urine examination using Auto Analyzer AU 680 Beckman 1071019”, to study scores such as haemoglobin levels, bleeding time, clotting time, total leucocyte count, platelet count, random blood sugar, serum creatinine, urine analysis: absence of blood, neutrophils or bacteria, ultrasonography of abdomen (Philips), (Contrast Enhanced CT abdomen (128 -slice CT scanners SIEMENS) was done if inconclusive on clinical evaluation coupled with ultrasonography of the abdomen) a RIPASA6 and modified Alvarado7,8 scores was calculated. The abdominal ultrasonography findings indicative of acute appendicitis include a non-compressible appendix characterized as a blind-ending tubular aperistaltic structure, an appendix diameter exceeding 6 mm or a maximal mural wall thickness greater than 2 mm, diffuse hypoechogenicity, a distended appendix lumen containing hyperechoic or anechoic material, periappendicular fluid accumulation, hyperechoic mesoappendix, and pericaecal adipose tissue.21 Following clinical assessment and indicative ultrasonography results, the patient will undergo laparoscopic appendectomy after obtaining written informed consent for the procedure. Laparoscopic appendicectomy is performed under aseptic conditions and general anesthesia in the supine Trendelenburg position. Pneumoperitoneum is established with a Foley catheter in the bladder. After placing a 10mm trocar at the umbilicus, intra-abdominal exploration begins. Then, two 5mm secondary ports are inserted in the left and right lumbar quadrants or suprapubic areas. The appendix will be located using the cecum's taenia coli, retracted with a grasper, the mesoappendix dissected from its base, and the appendix ligated and transected. Histopathological analysis of the appendectomy specimen will follow intraoperative findings. After surgery, the patient will be monitored in the general surgery recovery room for vital signs and wound healing. After 24 hours, the patient will be observed in the general surgery ward until discharge. In Histopathological examinations, the appendicectomy specimens are considered as normal appendix, catarrhal-stage appendicitis, suppurative-stage appendicitis, gangrenous appendicitis, or perforated appendicitis, which will be regarded as the gold standard.12 Sample size: The sample size was calculated using the formula n = z2 x sensitivity x (1-sensitivity)/I2 x prevalence , z = 1.96 for 95% confidence Interval, Sensitvity = 94.59, Prevalence = 10%2, Absolute Precision (l) = 2, Estimated sample size = 〖((1.96)2 x 94.5x (100-94.5))/(2^2 x 10 )〗^ = 49.8; Sample size= 50. A total of 70 samples were collected during the study period. Statistical analysis: Data was recorded by the participants on a structured proforma. Data entry and analysis were done using Windows Excel 2019 (Microsoft Corporation, Redmond, WA). All the entries were double-checked for any possible errors. Frequencies, proportions, and percentages were calculated for qualitative data. The mean and standard deviation were calculated for quantitative data. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the RIPASA and modified Alvarado scores were calculated using Med-Calc, an easy-to-use statistical software, with histopathology as the gold standard. Statistical analysis was performed using IBM SPSS Statistics Version 26 (IBM Corp, Somers, NY, USA). Ethical Considerations: The protocol was approved by the Institutional Ethics Committee before the initiation of patient recruitment. All participants provided written informed consent. Institutional Ethics Committee approval was obtained: (IEC No. 1146; Letter Roc. No: AS/12/TPAC/SVIMS/2017).

Baseline characteristics: In the present study, patients aged 18-60 years were included, with a mean age of 32.44 ± 11.38 years; the majority of patients belonged to the 2nd and 3rd decades. 51.4% of the patients were in the 18–30 years age group, followed by 32.9% in the 31–45 years age group, and the least represented age group, those above 46 years, with 15.7%. Males outnumbered the females almost 2 to 1. Both Sexes were affected, with a majority of 71% males followed by 29% females. Raja Isteri Pengiran Anak Saleha Appendicitis Scoring System findings: 100% of patients presented with RIF pain, followed by 75 % who presented with nausea or vomiting. 33 % presented with anorexia, and 28.57 % presented with migratory RIF pain in Figure 1. One hundred percent of patients were found to have RIF tenderness, followed by 54.28% of patients who had rebound tenderness. 41.42% of patients exhibited guarding, 33% had fever, and 17.14% presented with the roving sign, as shown in Figure 2. According to the categories of the final score of RIPASA, 86% of males are in a high probability category, and 90% of females are in the same category. Fourteen % of males fall into a low probability category, followed by 10% of females in the same category. Nil cases from both probabilities are unlikely and definite acute appendicitis, shown in Table 1. In this Study, the table of RIPASA Scores shows that patients with a RIPASA score of >7.5 are 62 patients, accounting for 89%, followed by patients with a RIPASA score of <7.5, which are 8, accounting for 11%. In the table with comparison of RIPASA Score and HPE, the total number of histopathology report positive and RIPASA score >7.5 was 60, followed by histopathology report positive and RIPASA score < 7.5 was 4, followed by Histopathology report negative and RIPASA> 7.5 was 2, and Histopathology report negative and RIPASA < 7.5 was 4, P value of <0.001 chi-square test: significant as shown in Table 2. In this study, sensitivity of RIPASA was 93.76 % with 95 % confidence interval (85-97.54) and specificity was 66.67 % with confidence interval (30 -90.32) and positive predictive value showed with an estimate of 96.77 % with 95 % confidence interval (88.98 - 99.11) and Negative predictive value showed with an estimate of 50 % with 95 % confidence interval (21.52 – 78.48) and Diagnostic accuracy of RIPASA is high (91.43 %) shown in table 3. Table 1 shows the Gender-wise distribution with categories of final score in RIPASA Gender Probability is Unlikely (<5) Low Probability (5–7) High Probability (7.5–11.5) Definite AA (>12) Male 0 7 43 0 Female 0 1 19 0 Table 2 Compares RIPASA Scoring and Histopathology. RIPASA HISTOPATHOLOGY TOTAL P value POSITIVE NEGATIVE >7.5 60 2 62 <0.001 <7.5 4 4 8 64 6 70 Table 3 shows the statistical analysis of RIPASA Parameter RIPASA Estimate Lower-Upper 95% CI Sensitivity 93.75% (85 - 97.54¹ ) Specificity 66.67% (30 - 90.32¹ ) PPV (95%CI) 96.77% (88.98 - 99.11¹ ) NPV (95%CI) 50% (21.52 - 78.48¹ ) DA 91.43% (82.53 - 96.01¹ ) Modified Alvarado Scoring System findings: According to the signs of MASS scoring, the Gender differentiation was 71% male and 29% female. 76 % of patients presented with nausea and vomiting, followed by 33 % patients presenting with anorexia, followed by 28.6% of patients presenting with migratory RIF pain, as shown in Figure 3. One hundred percent of patients were found to have RIF tenderness, 54.28% of patients had rebound tenderness, and 33% of patients had fever, as shown in Figure 4. According to the categories in the final score, Modified Alvarado indicates that 76% of males have a high probability, and 70% of females also belong to this category. 14% of males have an unlikely probability, followed by10 % of females in the same category. 10% of females and 6% of males came under the definite appendicitis category, shown in Table 4. In this study, patients with MASS of >6 are 58 (83%), and those with MASS of <6 are 12 (17%). In this study, the Histopathology report Was Positive, and the modified Alvarado score was> 6 in 57 cases, and it was < 6 in 7 cases. Histopathology report: Negative, and the Modified Alvarado score of >6 was 1. Histopathology report: Negative and Modified Alvarado score of <6 was 5. P-value of <0.000 chi-square test: significant shown in table 5. In this study, sensitivity was 89.06 % with 95 % confidence interval (79.1- 94.6) and specificity was 83.33 % with confidence interval (43.65 -96.99) and positive predictive value showed with an estimate of 98.28 % with 95 % confidence interval (90.86 - 99.7) and Negative predictive value showed with an estimate of 41.67 % with 95 % confidence interval (19.33 – 68.05) and Diagnostic accuracy of RIPASA is high (88.57%) shown in table: 6. Table 4 shows the Gender-wise distribution with categories in the final score in MASS Gender Variables Probability is unlikely (<5) Low probability 5-6 High probability 6-7 Definite AA>8 Male 7 2 38 3 Female 2 2 14 2 Table 5 shows a comparison of MASS and Histopathology MASS HPE TOTAL P value POSITIVE NEGATIVE >6 57 1 58 <0.001 <6 7 5 12 64 6 70 Table 6 shows the statistical analysis of MASS MASS Estimate ** Lower – Upper 95% CI Sensitivity 89.06% (79.1 - 94.6¹ ) Specificity 83.33% (43.65 - 96.99¹ ) PPV (95%CI) 98.28% (90.86 - 99.7¹ ) NPV (95%CI) 41.67% (19.33 - 68.05¹ ) DA 88.57% (79.04 - 94.09¹ ) Comparison of the Validity of RIPASA & MASS Scoring System: In this study, the RIPASA score shows a sensitivity of 93.75%, specificity of 66.67%, positive predictive value of 96.77%, negative predictive value of 50%, and a diagnostic accuracy of 91.43%. The modified Alvarado score shows a sensitivity of 89.06%, specificity of 83.33%, positive predictive value of 98.28%, negative predictive value of 41.67%, and a diagnostic accuracy of 88.57% as shown in Figure 5. It can be seen that the RIPASA scoring system has better sensitivity, positive predictive value, and diagnostic accuracy as compared to MASS.

In our study, we compared the recent scoring system, RIPASA, which is based on the Asian population, with MASS, which is mainly based on the Western population. A total of 70 patients were included. RIPASA and MASS were calculated using clinical parameters and suggestive ultrasonography findings. Patients were subjected to a laparoscopic appendicectomy. The histopathology specimen was collected and used to confirm the final diagnosis. A total of 70 patients were included in our study, comprising 50 males and 20 females. The ratio was 2.5:1, indicating a more male preponderance in our study, compared to a survey conducted by Moussa BS et al., 10 in 2022, which recorded a 1.4:1 male-to-female ratio. A prospective study by Priya Kushwah et al.,9 (2020) reported a male-to-female ratio of 1.67:1. The Male population is more prevalent. This implies AA is more common among males. According to age distribution, the maximum number of patients falls within the young adult age group, 2nd to 3rd decade, accounting for approximately 51.4%. In contrast, the minimum number of patients is found in the age group > 4th decade, at about 15.5%. The mean age of patients is 32.4 yrs+/- 11.34 years. A prospective study conducted over 1 year by Moussa BS et al.,10 reported a mean age of the patients as 30.10 ± 9.69 years, which is similar to the distribution in our study. Sensitivity: In the current study, the RIPASA score demonstrates a sensitivity of 93.75%. A survey conducted in 2011 at RIPAS Hospital, Brunei, by Shuaib A et al., 11 ,which was among the first to use the RIPASA score, found a sensitivity of 98%, slightly higher than the sensitivity in our study. This could be attributed to the larger sample size (192 subjects). Our study is in concordance with a prospective study in Turkey12 conducted between 2017 and 2018. The RIPASA scoring system was compared with the modified Alvarado scoring system and found to have a higher sensitivity (94%) compared to the latter (88%). The study revealed a 9.8% difference between the AUCs for the two scoring systems. The current study shows similar AUC for the two scoring systems. Our study concurs with a recent survey conducted in Puducherry13 between 2017 and 2018. RIPASA, Alvarado, and Tzanakis scoring systems were compared in diagnosing AA. The above-stated study reported sensitivity (90%) and specificity (66.7%) for RIPASA. A retrospective study done in Andhra Pradesh14 in the period November 2018-March 2020, where sensitivity, specificity, PPV, NPV, and diagnostic accuracy of RIPASA and the modified Alvarado scoring system were compared. The study demonstrated sensitivities of 91% and 85% for RIPASA and MASS, respectively. The results of the current study are in concordance with the above-stated study. Specificity: The current study shows a specificity of 66.67% and 83% in RIPASA and MASS, respectively. The first study on the development of the RIPASA score was conducted in 2011 at the RIPAS Hospital in Brunei by Shuaib A et al., 11 It showed a specificity of 67%, which is similar to the specificity in our study. A prospective study using the RIPASA score for the diagnosis of acute appendicitis in 2020, reported by Priya Kushwah et al.,9 in India, found a similar specificity for RIPASA (65%). This may be attributed to a smaller sample size. In a retrospective study done at Rajahmundry West, Andhra Pradesh14, in 2021, the specificity of RIPASA and MASS was found to be 71% and 57% respectively. In the current study, the specificity of RIPASA and MASS is 66% and 83%, respectively. The specificity of MASS is higher in our study, which differs from other studies conducted among the Indian population. The specificity in our study is in concordance with a recent survey conducted in Puducherry13 in 2019, which found a specificity of 66%. Positive predictive value (PPV) : In our study, the PPV for RIPASA and MASS are 96.77% and 98%, respectively, which is significantly higher than the 67% PPV reported in a prospective observational study conducted in 2020 at Priya Kushwah et al.,9 for the clinical evaluation of the RIPASA scoring system. According to a study by Chong et al.,6 in 2011, which compared the RIPASA scoring system with the Alvarado scoring system, the PPV of RIPASA was found to be 85.34%, which is 11% lower than the PPV in our study. The PPV of MASS was found to be 86.25%, which is 12% lower than in our study. Our results for PPV are similar to those of a comparable study conducted in Turkey12, which compared the RIPASA and modified Alvarado scoring systems. The PPV of the study was 97.5% for RIPASA, as shown in the table. The PPV of our study is also similar to that of a recent survey conducted in Puducherry13. Negative predictive value (NPV): The negative predictive value in our study is 50%, which is similar to a study done in Rajahmundry, Andhra Pradesh14, where the PPV was 45%. The current study's NPV of the RIPASA score is in concordance with the NPV (53.3%) of the RIPASA score reported in a 2021 survey conducted in Puducherry13. A study by Priya Kushwah et al.,9 showed a very high NPV of 85%, which is almost double (1.8 times) the NPV of our research. Diagnostic accuracy: The diagnostic accuracy for RIPASA in our study is 91.4%, and for MASS, it is 88.5%. A 2017 study in Turkey12 reported a diagnostic accuracy of 85% for RIPASA and 73% for MASS, whereas a study by Priya Kushwah et al.,9 showed a diagnostic accuracy of 70% for RIPASA. A retrospective study in Andhra Pradesh14 reported a diagnostic accuracy of 89% for RIPASA and 82% for MASS, which aligns with our findings. Another study conducted in Karnataka16 yielded similar results to our research, with a diagnostic accuracy of 88% for RIPASA, whereas the value was lower (63%) for MASS. LIMITATIONS: This study was conducted at a single centre at a tertiary care centre in Andhra Pradesh, so the results lack external validity. The study has a small sample size due to the exclusion of subjects under 18 years of age. A larger sample size could improve the diagnostic accuracy and specificity of the study. This study did not analyse the outcome of patients who were managed conservatively and who did not undergo a surgical procedure.

The RIPASA score outperforms the modified Alvarado score in terms of sensitivity (93% vs. 89%), negative predictive value (50% vs. 41%), and diagnostic accuracy (91% vs. 88%). In contrast, it is nearly similar to MASS in terms of PPV (96% and 98%). The parameters in the RIPASA scoring system can be quickly and easily determined through a brief clinical history, examination, and a few laboratory tests (leukocyte count, urinalysis). Currently, the RIPASA score is a more effective diagnostic tool than the others within the Indian population, as it can be obtained using simple clinical and laboratory data without the need for costly imaging studies such as a CT scan. Disclosure statement: No potential conflict of interest was reported by the authors

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