Acute appendicitis remains one of the most frequent causes of acute abdominal pain requiring emergency surgical intervention, with the vermiform appendix forming a key focus of assessment in patients presenting with right iliac fossa symptoms [1]. Despite being common, the diagnosis is often challenging because clinical presentations can overlap with other intra-abdominal and pelvic conditions, and delayed or missed diagnosis increases the risk of perforation and sepsis, while overdiagnosis contributes to unnecessary appendectomy [5]. To improve bedside decision-making, a range of structured diagnostic approaches have been developed, combining clinical features, examination findings, and laboratory parameters into validated scoring systems. The Alvarado score and its modified versions are among the most widely applied tools and have been evaluated in multiple prospective cohorts for their ability to stratify patients into low, intermediate, and high probability categories for appendicitis [4,6]. However, performance varies with patient population and clinical setting, and scoring systems must be interpreted within the broader context of disease prevalence and local practice patterns [5]. Imaging, particularly ultrasonography, is frequently used as a complementary modality to refine diagnostic certainty and reduce negative appendectomies. Prior work comparing ultrasound with clinical scoring has shown that combining structured clinical assessment with imaging can improve diagnostic confidence and guide surgical decision-making, particularly in equivocal cases [2]. In paediatric patients, where diagnostic uncertainty is often greater, systematic clinical evaluation has also been emphasized to support accurate risk stratification and appropriate escalation to imaging or observation [3]. Given the ongoing need to balance timely operative management against avoidance of unnecessary surgery, contemporary practice increasingly relies on combining clinical scoring systems with targeted imaging and clinical judgement. In this context, evaluating and comparing the diagnostic performance of commonly used scoring systems remains clinically relevant for optimizing outcomes and resource use in suspected acute appendicitis [4–6]. Objectives Primary objective •To evaluate the diagnostic performance of clinical scoring systems in patients with suspected acute appendicitis, using histopathology as the reference standard. Secondary objectives •To compare the diagnostic accuracy (sensitivity, specificity, PPV, NPV, and overall accuracy) of the RIPASA score (cut-off ≥7.5) and the modified Alvarado score (cut-off ≥7). •To describe the study population’s clinical profile, intraoperative findings, and histopathological outcomes (including the negative appendectomy rate).

Study design, setting, and duration A prospective observational study was conducted in the Department of General Surgery at Barasat Government Medical College & Hospital, West Bengal, India, over 12 months following Institutional Ethics Committee approval. Study population Patients aged 15–60 years admitted with a clinical suspicion of acute appendicitis and planned for operative management were enrolled. Inclusion criteria •Age 15–60 years •Clinically suspected acute appendicitis and taken up for surgery Exclusion criteria •Age <15 years •Pregnancy •Right iliac fossa mass •History suggestive of alternative diagnoses (e.g., prior urolithiasis or pelvic inflammatory disease) Sample size estimation Sample size was calculated using the formula N = Z²pq/d², with Z = 1.96, p = 0.14, q = 0.86, and d = 0.075, yielding a minimum required sample size of 82. Accordingly, 82 patients were included in the final analysis. Data collection and clinical assessment Demographic details and clinical variables (symptoms, signs, and laboratory findings) were recorded at presentation using a structured proforma. Baseline investigations included total leukocyte count, differential count/neutrophil percentage, and urine analysis. Scoring systems and cut-offs For each patient, both scoring systems were calculated: •Alvarado score (8 parameters; item weights 1–2) •RIPASA score (18 parameters; item weights 0.5–2) For diagnostic categorization, the following cut-offs were applied: •Alvarado ≥7: high probability of appendicitis •RIPASA ≥7.5: high probability of appendicitis The decision to operate was made by the treating surgical team based on standard clinical judgment; scores were computed for study evaluation. Operative findings and reference standard Intraoperative findings (appendix position and gross appearance) were documented. All resected appendices were sent for histopathological examination, which served as the reference standard for confirming acute appendicitis versus normal appendix. Outcomes The primary outcome was the diagnostic performance of RIPASA and Alvarado scores against histopathology, reported as: •Sensitivity, specificity, PPV, NPV, and accuracy Secondary outcomes included: •Distribution of score categories at the specified cut-offs •Intraoperative findings and negative appendectomy rate (normal histopathology) Statistical analysis Data were entered in Microsoft Excel and analysed using SPSS. Categorical variables were summarized as frequency and percentage and compared using the chi-square test. Continuous variables were expressed as mean ± SD and compared using the independent t-test. A p-value ≤0.05 was considered statistically significant. Ethical approval and consent The study protocol was reviewed and approved by the Institutional Ethics Committee of Barasat Government Medical College & Hospital, West Bengal, prior to initiation. Written informed consent was obtained from all participants (or their legally authorized representatives where applicable). Participant confidentiality was maintained, and the study was conducted in accordance with standard ethical principles for biomedical research.

1) Study population and baseline profile A total of 82 patients aged 15–60 years who underwent surgery for suspected acute appendicitis were included in the analysis. The mean age was 27.87 ± 10.11 years, with the largest proportion in the ≤20-year age group (36.6%). Females comprised 52.4% (43/82) of the cohort and males 47.6% (39/82). Regarding dietary pattern, 76.8% (63/82) were classified as having a high-fibre diet and 23.2% (19/82) as low-fibre. Baseline characteristics are summarised in Table 1. Table 1. Baseline characteristics of the study population (N = 82) Characteristic Value Age (years), mean ± SD 27.87 ± 10.11 Age group, n (%) ≤20 years 30 (36.6) 21–30 years 23 (28.0) 31–40 years 19 (23.2) 41–50 years 7 (8.5) 51–60 years 3 (3.7) Sex, n (%) Female 43 (52.4) Male 39 (47.6) Diet pattern, n (%) High fibre 63 (76.8) Low fibre 19 (23.2) 2) Clinical presentation and laboratory profile Most patients presented early, with symptoms lasting <48 hours in 69/82 (84.1%). Migratory pain was reported in 42/82 (51.2%), anorexia in 34/82 (41.5%), and nausea/vomiting in 51/82 (62.2%). On examination, right iliac fossa (RIF) pain was present in 82/82 (100%) and RIF tenderness in 78/82 (95.1%). Rebound tenderness was observed in 63/82 (76.8%), guarding in 26/82 (31.7%), and Rovsing’s sign in 29/82 (35.4%). Fever was documented in 59 out of 82 (72.0%). Laboratory evaluation showed leukocytosis in 56/82 (68.3%) and neutrophilia (>75%) in 49/82 (59.8%) (mean neutrophil percentage 73.91 ± 8.63). Urine analysis was negative in most cases (77/82; 93.9%). Clinical and laboratory characteristics are summarised in Table 2, and the prevalence profile is shown in Figure 1. Figure1. Prevalence of clinical features and laboratory findings (N=82) Table 2. Presenting symptoms, signs, and laboratory findings (N = 82) Variable n (%) Duration of symptoms <48 hours 69 (84.1) >48 hours 13 (15.9) Migratory pain Yes 42 (51.2) No 40 (48.8) Anorexia Yes 34 (41.5) No 48 (58.5) Nausea/vomiting Yes 51 (62.2) No 31 (37.8) RIF pain 82 (100.0) RIF tenderness Yes 78 (95.1) No 4 (4.9) Rebound tenderness Yes 63 (76.8) No 19 (23.2) Guarding Yes 26 (31.7) No 56 (68.3) Rovsing’s sign Yes 29 (35.4) No 53 (64.6) Fever Yes 59 (72.0) No 23 (28.0) Increased WBC count Yes 56 (68.3) No 26 (31.7) Neutrophils >75% 49 (59.8) ≤75% 33 (40.2) Neutrophil %, mean ± SD 73.91 ± 8.63 Urine analysis Negative 77 (93.9) Positive 5 (6.1) 3) Distribution of RIPASA and Alvarado score categories Using the prespecified diagnostic thresholds, 66/82 (80.5%) patients had a RIPASA score ≥7.5, whereas 44/82 (53.7%) had an Alvarado score ≥7. Thus, RIPASA classified a larger proportion of patients into the higher-probability category for acute appendicitis (Table 3). Table 3. Distribution of RIPASA and Alvarado scores by cut-offs (N = 82) Score category n (%) RIPASA ≥7.5 66 (80.5) <7.5 16 (19.5) Alvarado ≥7 44 (53.7) <7 38 (46.3) Figure 2. Diagnostic performance of RIPASA vs Alvarado (histopathology reference) 4) Intraoperative findings and histopathology Intraoperatively, the appendix was most commonly located in the retrocaecal position (56/82; 68.3%), followed by the pelvic position (18/82; 22.0%) (Table 4). On gross appearance, 44/82 (53.7%) appendices were described as inflamed, while 21/82 (25.6%) appeared normal. Features consistent with complicated appendicitis (abscess, gangrenous, or perforated appendix) were observed in 17/82 (20.7%). Histopathology confirmed acute appendicitis in 69/82 (84.1%), while 13/82 (15.9%) specimens were reported as normal, corresponding to a negative appendectomy rate of 15.9% (Table 4). Table 4. Intraoperative findings and histopathology (N = 82) Finding n (%) Appendix position Retrocaecal 56 (68.3) Pelvic 18 (22.0) Preileal 3 (3.7) Postileal 1 (1.2) Subcaecal 4 (4.9) Gross appearance Inflamed 44 (53.7) Normal 21 (25.6) Gangrenous 10 (12.2) Perforated 5 (6.1) Abscess 2 (2.4) Histopathology Acute appendicitis 69 (84.1) Normal appendix 13 (15.9) 5) Diagnostic performance of RIPASA and Alvarado (reference: histopathology) At the chosen cut-offs, RIPASA demonstrated higher overall diagnostic performance than Alvarado. Using histopathology as the reference standard, RIPASA yielded TP=64, TN=11, FP=2, FN=5, corresponding to sensitivity 92.75%, specificity 84.62%, PPV 96.97%, NPV 68.75%, and accuracy 91.46%. In comparison, Alvarado produced TP=41, TN=10, FP=3, FN=28, with sensitivity 59.42%, specificity 76.92%, PPV 93.18%, NPV 26.32%, and accuracy 62.20% (Table 5). The comparative performance profile is illustrated in Figure 2. Table 5. Diagnostic performance of RIPASA and Alvarado scores (histopathology reference) Measure RIPASA (cutoff ≥7.5) Alvarado (cutoff ≥7) True Positive (TP) 64 41 False Positive (FP) 2 3 True Negative (TN) 11 10 False Negative (FN) 5 28 Sensitivity (%) 92.75 59.42 Specificity (%) 84.62 76.92 PPV (%) 96.97 93.18 NPV (%) 68.75 26.32 Accuracy (%) 91.46 62.20 6) Score behaviour by outcome strata (TP/FP/TN/FN) When scores were examined by outcome strata against histopathology, RIPASA showed clearer separation between true appendicitis and non-appendicitis groups than Alvarado (Table 6). Among histopathology-positive cases correctly classified by RIPASA (true positives), the mean RIPASA score was 10.52 ± 1.54 (n=64; range 8.0–14.5), compared with 6.82 ± 0.34 (n=11; range 6.0–7.0) among true negatives. False negatives had similarly low RIPASA scores (6.80 ± 0.45; n=5; range 6.0–7.0), consistent with missed cases clustering below the cutoff. False positives were uncommon (n=2) with a mean score of 7.14 ± 1.16, indicating limited misclassification close to the threshold. For Alvarado, true positives had a mean score of 8.41 ± 0.63 (n=41; range 7.0–10.0), while true negatives clustered lower (5.10 ± 0.74; n=10; range 4.0–6.0). Notably, false negatives formed a sizeable group (n=28) with a mean Alvarado score of 5.61 ± 0.57 (range 4.0–6.0), reflecting substantial downward shift below the cutoff and consistent with the lower sensitivity observed. False positives were few (n=3) and had a mean score of 8.00 ± 1.00, overlapping with the true-positive range, suggesting that when Alvarado misclassified histopathology-negative cases, it tended to do so at higher score values. Table 6. Mean RIPASA and Alvarado scores by diagnostic classification (reference: histopathology) Score / Stratum n Mean ± SD Range RIPASA (cutoff ≥7.5) True Positive (TP) 64 10.52 ± 1.54 8.0–14.5 False Positive (FP) 2 7.14 ± 1.16 6.3–8.0 True Negative (TN) 11 6.82 ± 0.34 6.0–7.0 False Negative (FN) 5 6.80 ± 0.45 6.0–7.0 Alvarado (cutoff ≥7) True Positive (TP) 41 8.41 ± 0.63 7.0–10.0 False Positive (FP) 3 8.00 ± 1.00 7.0–9.0 True Negative (TN) 10 5.10 ± 0.74 4.0–6.0 False Negative (FN) 28 5.61 ± 0.57 4.0–6.0

In this prospective cohort of 82 patients operated for suspected acute appendicitis, RIPASA (cut-off ≥7.5) outperformed Alvarado (cut-off ≥7) against histopathology, with higher sensitivity (92.75% vs 59.42%), higher NPV (68.75% vs 26.32%), and higher overall accuracy (91.46% vs 62.20%). This performance pattern aligns with Akbar et al. (2019), who reported that RIPASA generally achieves high diagnostic yield in routine surgical populations and tends to be more sensitive than traditional scores—typically in a clinically useful range (often high-80s to mid-90s sensitivity), which is consistent with our observed >90% sensitivity while maintaining acceptable specificity (84.62%) [7]. Chong et al. (2011) directly compared RIPASA and Alvarado and concluded that RIPASA is often better calibrated for Asian/South-Asian case-mix, with improved sensitivity at commonly used thresholds compared with Alvarado [8]. Our data echo that direction: despite similar PPV (RIPASA 96.97%, Alvarado 93.18%), RIPASA’s markedly higher sensitivity translated into far fewer false negatives (5 vs 28), which is exactly the practical advantage noted in comparative studies—reducing the chance of missing appendicitis in borderline presentations [8]. From the Alvarado perspective, Gupta et al. (2023) synthesised validation evidence and highlighted that Alvarado’s performance varies substantially across regions and study designs, with sensitivity frequently dropping when applied outside the populations where it was originally popularised, while specificity may remain moderate [9]. That “variable sensitivity” narrative fits our results: Alvarado specificity was acceptable (76.92%), but sensitivity was comparatively low (59.42%), producing a large false-negative stratum (n=28) clustered below the cut-off (mean score 5.61), suggesting under-triage in our setting if Alvarado ≥7 alone were used to rule in surgery [9]. Butt et al. (2014) described RIPASA as a newer score intended to reduce negative appendectomy and improve diagnostic confidence, particularly in settings where imaging may be selective rather than universal [10]. In our cohort, histopathology was normal in 15.9% (13/82), which is within the commonly reported “real-world” negative appendectomy band (often ~10–25% depending on imaging access and thresholds). With RIPASA’s high PPV (96.97%) and low FP count (2), our findings are consistent with the idea that RIPASA can support more targeted operative decision-making without inflating unnecessary appendectomies [10]. Frountzas et al. (2018), in a meta-analytic comparison, generally found RIPASA to be more sensitive than Alvarado, while specificity differences are often smaller and context-dependent [11]. Our results mirror that meta-analytic shape: the main separation is sensitivity (~93% vs ~59%) and downstream NPV/accuracy, whereas specificity remained in a broadly comparable range (RIPASA 84.62%, Alvarado 76.92%)—suggesting RIPASA’s “gain” in our setting comes primarily from capturing more true appendicitis cases rather than by dramatically reducing false positives [11]. This is also coherent with the design logic of RIPASA. In the original development paper, Chong et al. (2010) constructed RIPASA by incorporating additional demographic and symptom variables to better match Asian clinical presentations and to improve discrimination at the bedside [12]. In our cohort, RIPASA classified a larger proportion of patients as high probability (80.5% ≥7.5) compared with Alvarado (53.7% ≥7), yet it still maintained specificity >80%. That combination suggests the threshold used here achieved a clinically useful balance—broad capture of true disease (histopathology positive 84.1%) without a large surge in false positives [12]. Beyond “diagnosis yes/no,” severity is also clinically relevant. Karapolat (2019) evaluated whether RIPASA relates to pathological staging and suggested that higher scores may correlate with more advanced inflammation [13]. Our operative spectrum showed 20.7% complicated appearances (gangrenous/perforated/abscess), and RIPASA true positives had a relatively high mean score (10.52 ± 1.54). While we did not formally model stage prediction, the clustering of higher RIPASA values among histopathology-confirmed appendicitis is directionally compatible with literature suggesting that higher scores tend to accompany more convincing/advanced disease phenotypes [13]. Favara et al. (2022) further summarised comparative evidence and reinforced that RIPASA often performs well in non-Western cohorts, but also emphasised heterogeneity by threshold choice, operator assessment, and verification methods [14]. That caveat matters here: our gold standard was histopathology in an operated cohort, which typically inflates PPV (as seen in both scores: >93%) while making NPV more sensitive to how many “low-score” patients still proceeded to surgery. In this context, RIPASA’s higher NPV (68.75%) compared with Alvarado (26.32%) is particularly meaningful, because it indicates that a low RIPASA score was more consistent with normal histology than a low Alvarado score in our surgical population [14]. Sex and demographic weighting can also influence score transportability. Capoglu et al. (2022) discussed that models incorporating gender (or those applied in sex-imbalanced cohorts) can shift predictive behaviour, especially where differential diagnoses mimic appendicitis (e.g., gynaecologic causes in females) [15]. Our cohort had a slight female predominance (52.4%), and the negative appendectomy rate (15.9%) is plausibly influenced by this diagnostic complexity. In such settings, a scoring system with broader variable capture (as RIPASA intends) may retain sensitivity without excessively penalising specificity, though the optimal threshold may still require local calibration depending on referral pathways and differential diagnosis prevalence [15]. Methodologically, our results also reflect threshold effects and “borderline-zone” behaviour. Farooq et al. (2020) compared ultrasound with Alvarado using histopathology as gold standard and highlighted that combining clinical scores with imaging can meaningfully shift false-negative and false-positive rates—often improving rule-out safety when ultrasound is available and high quality [16]. In our data, the main weakness of Alvarado was false negatives (28), implying that an “Alvarado-low” group could still harbour appendicitis; a pragmatic pathway in similar settings is to escalate low/intermediate scores to imaging or observation rather than discharge, especially when clinical suspicion persists [16]. Finally, placing our findings into a broader diagnostic strategy, ultrasound remains a common adjunct where CT access, cost, or radiation concerns limit routine cross-sectional imaging. Farooq et al. (2020) and similar ultrasound-versus-score comparisons generally suggest that ultrasound can enhance specificity and reduce negative appendectomies when positive, but its sensitivity can be operator-dependent and variable; therefore, a high-sensitivity clinical score can still be valuable as the initial triage step [17]. In practical terms, our observed RIPASA sensitivity (92.75%) with acceptable specificity (84.62%) supports RIPASA as a strong front-line tool in this regional surgical setting, while acknowledging that integrating imaging (particularly for low-score but clinically concerning cases) could further reduce missed appendicitis and help drive the negative appendectomy rate below the ~15–20% band seen here, depending on local resources and operator expertise [17]. Limitations This was a single-centre study with a modest sample size (N=82) and inclusion of only operated patients, which may introduce selection/verification bias and inflate PPV. Imaging findings were not uniformly incorporated, and the fixed cut-offs (RIPASA ≥7.5; Alvarado ≥7) may not represent the optimal thresholds for all populations, limiting generalisability.

In this study of 82 patients operated for suspected acute appendicitis, RIPASA (cut-off ≥7.5) demonstrated superior diagnostic performance compared with Alvarado (cut-off ≥7) using histopathology as the reference standard, with higher sensitivity (92.75% vs 59.42%), NPV (68.75% vs 26.32%), and overall accuracy (91.46% vs 62.20%). RIPASA, therefore, appears more reliable for identifying patients with acute appendicitis in our setting and may help support earlier decision-making and potentially reduce missed cases when used alongside clinical judgment and appropriate imaging.

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