Performance and diagnostic accuracy of scoring systems in patients with suspected adult appendicitis

doi:10.21203/rs.3.rs-2240287/v1

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Research Article

Performance and diagnostic accuracy of scoring systems in patients with suspected adult appendicitis

https://doi.org/10.21203/rs.3.rs-2240287/v1

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published 06 Jul, 2023

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Background

This study aims to determine the most accurate appendicitis scoring system and optimal cutoff points for each scoring system.

Methods

This single-centred prospective cohort study was conducted from January-to-June 2021, involving all patients admitted on suspicion of appendicitis. All patients were scored according to the Alvarado score, Appendicitis Inflammatory Response (AIR) score, Raja Isteri Pengiran Anak Saleha (RIPASA) score and Adult Appendicitis score (AAS). The final diagnosis for each patient was recorded. Sensitivity and specificity were calculated for each system. Receiver operating characteristic (ROC) curve was constructed for each scoring system and the area under the curve (AUC) was calculated. Optimal cutoff scores were calculated using Youden’s Index.

Results

A total of 245 patients were recruited with 198 (80.8%) patients underwent surgery. RIPASA score had the highest sensitivity (72.7%) and specificity (62.3%) at an optimal score of 8.5 with AUC 0.724, followed by the AAS (sensitivity 60.2%, specificity 75.4%, optimal score 14, AUC 0.719), AIR score (sensitivity 76.7%, specificity 52.2%, optimal score 5, AUC 0.688) and Alvarado score (sensitivity 69.9%, specificity 62.3%, optimal score 5, AUC 0.681). Multiple logistic regression revealed anorexia (p-value 0.018), right iliac fossa tenderness (p-value 0.005) and guarding (p-value 0.047) as significant clinical factors independently associated with appendicitis.

Conclusion

Appendicitis scoring systems have shown moderate sensitivity and specificity in our population. The RIPASA scoring system has shown to be the most sensitive, specific and easy-to-use scoring system in the Malaysian population whereas the AAS is most accurate in excluding low-risk patients.

Adult

Appendectomy

Appendicitis

ROC curve

Acute abdomen is among the most common presentations to the Emergency Department accounting for 7–10% of cases. Among these, 3–4% of the patients would later be diagnosed to have acute appendicitis (AA), which is the commonest surgical emergency [1, 2]. Appendectomies account for 2–4% of surgical procedures performed in the West [3, 4]. The incidence of appendicitis varies greatly between regions, showing a greater preponderance in Asian populations. In the United State of America, it is about 108 cases per 100,000 population, whereas in the United Kingdom, it is 63 per 100,000; and about 206 per 100,000 population in South Korea. A general male gender preponderance is seen, with an incidence rate 1.2 to 1.4 times greater than females. Conversely, the lifetime risk for AA is 8.9–13.3% in males and 8.7–13.4% in females; about 1.5 times greater in the Asian population [5–7]. The spectrum of disease can range from an inflamed appendix, phlegmonous appendicitis, perforated appendicitis and abscess formation. Roughly, 13% of patients presenting for appendicitis will be diagnosed to be perforated, of which the main contributing factor is delays in presentation and intervention [8]. Surgery on patients with perforated appendix forming phlegmon and pelvic abscesses is technically more challenging with a threefold odds of morbidity [9]. Even so, one in eight patients treated conservatively would later develop a recurrence of the disease. Therefore, an accurate and timely diagnosis of appendicitis is imperative [10].

AA is traditionally diagnosed clinically whereby clinical history, physical signs and simple blood investigations are weighed to decide on the approach to management. Classical clinical findings include a history of right lower quadrant pain, nausea, fever, tenderness and abdominal guarding over McBurney’s point. These findings may be obscure in patients with early appendicitis and may also be present in other pathology. Patients with perforated appendicitis will present with a more severe clinical condition which includes sepsis, peritonitis and even portal pylephlebitis [11]. Differential diagnoses range from a variety of gastrointestinal, urinary tract and gynaecological conditions. Radiological advancements have led to the wider usage of ultrasonography and computed tomography (CT) in aiding the diagnosis of this condition [12]. However, in peripheral centres which are not equipped with such facilities, clinical judgement determines the need for surgery, observation or further radiological investigations. Clinical judgement alone yields a negative appendectomy rate of up to 30%. On the other hand, patients with inconclusive findings are often admitted for observation, which inevitably consumes healthcare resources. With the addition of ultrasonography, the negative appendectomy rates fall to 8% and are further reduced to 4.5% if computed tomography is used [13]. Liberal use of radio imaging, particularly CT scans, increases the detection and unnecessary surgical intervention for mild appendicitis which commonly resolves spontaneously [14].

A variety of clinical scoring systems have been introduced to aid in the diagnosis of AA, of which the most well-known is the Alvarado score. It has been shown to have lower sensitivity (36–68%) and specificity (64–82%) among Asian populations [15–17]. More recent scoring systems have also been designed such as the Appendicitis Inflammatory Response (AIR) score, the Adult Appendicitis score (AAS) and the Raja Isteri Pengiran Anak Saleha (RIPASA) score. These systems were developed using advanced statistics and mathematical models, providing more accurate weightage for each criterion assessed [18–21]. The RIPASA score was derived and validated with an Asian population in Brunei much mirroring that of the local Malaysian population. It has been shown to outperform the AIR score which was derived from a European population in Sweden. This is based on the evidence that the Alvarado score demonstrated a lower sensitivity and specificity when applied to Middle Eastern, Asian and Oriental populations [22, 23]. The AAS is the latest scoring system, developed in Helsinki, Finland in 2014 and validated in 2017 [20, 21]. Despite a wealth of evidence demonstrating the superiority of the AIR score, RIPASA score and AAS to the Alvarado score, there is a paucity of evidence directly comparing the RIPASA score and AAS [24]. The aim of this study was to assess and compare the sensitivity and specificity of various appendicitis scoring systems namely the Alvarado Scoring system, the AIR score, the RIPASA and the AAS as well as to define the optimal cut-off scores for predicting appendicitis and to assess additional clinical predictors for appendicitis.

This is a single-centre prospective cohort study conducted in Hospital Queen Elizabeth, Kota Kinabalu, Sabah. It is a tertiary-level centre servicing referrals from the Western and Northern coasts of Sabah. Data collection was conducted over 6 months, from January 2021 to June 2021. This study was approved by the Universiti Kebangsaan Malaysia ethical committee (UKM.FPR.SPI 800-2/28) and Malaysia Research Ethics Committee (NMRR-19-3689-51733 (IIR)).

All patients admitted for acute abdominal pain with suspicion of appendicitis during the study period were recruited. Inclusion criteria include age 16 years old and above, able to provide informed consent (patients 18 years and older); or minors under 18 years old who are able to provide assent with a legal guardian to provide informed consent. Patients excluded include pregnant patients, patients undergoing elective appendectomy, patients undergoing surgery for other indications and appendectomy as a side procedure, history of urolithiasis, history of appendectomy (stump appendicitis); and patients with a history of appendix phlegmon treated conservatively. Participants were assessed using the Alvarado score, AIR score, RIPASA score and Adult Appendicitis Score during admission. Those who underwent surgery had their operative findings recorded and the results of histology specimens traced. Histopathology is the gold standard for this group of patients. If appendectomy is not performed and an alternative diagnosis is made intraoperatively, the operative finding is taken as the gold standard. For non-operated patients, ultrasonography or computed tomography findings indicating appendicitis were accepted as the final diagnosis. For non-operated patients without radio imaging or inconclusive radio imaging studies, a follow-up of case files in 3 months is performed. Those who did not develop appendicitis within the period are considered negative for appendicitis [23].

This study aims to assess and compare the accuracy of scoring systems in diagnosing acute appendicitis. This is to be measured through sensitivity and specificity analysis as well as generating Receiver Operator Characteristic (ROC) curves to compare the Area Under Curve (AUC) of each scoring system. The assessment result of each scoring system will be compared against the “gold standard” in this case, histopathological assessment. By making reference to Bujang et al, with the prevalence of appendicitis estimated to be 20% in Asian populations, a minimum sample size of 245 subjects including 49 subjects having appendicitis was recruited to achieve a minimum power of 80% (actual power 81%) for detecting a change in the percentage value of sensitivity of a screening test from 0.50 to 0.70, based on a target significance level of 0.05 (actual p = 0.044) [25]. The minimum sample size required was calculated using PASS 11 software (PASS 11, NCSS, LLC, Kaysville, Utah, USA). The collected data were entered and analysed using IBM SPSS v26.0. Scores from each scoring system were calculated and tabulated according to the recommended thresholds for each system. The sensitivity, specificity and predictive values of each scoring system were then calculated. The ROC curves were constructed to compare the AUC for each scoring system. Optimal cutoff scores producing the largest area under the curve were calculated using Youden’s Index with MedCalc version 20.0 (MedCalc Software Ltd).

A total of 245 participants were recruited for the study, their demographic and clinical data are presented in Table 1. The participants are ages ranging from 16 to 74 years old with a mean of 32.5 years ± 13.3 years. Our patients present with an average duration of symptoms of 68 hours (2.8 days). 200 (81.6% of the participants had some form of premorbid illness including hypertension (5.3%), diabetes mellitus (2.9%) and bronchial asthma (2%). 90.6% of patients did not have any previous abdominal surgery. Of the 108 females recruited in the study, 21 (19.4%) were menstruating.

Table 1

The demographic and clinical data of acute appendicitis
Factors	Appendicitis		p-values
Factors	Yes (N = 176)	No (N = 69)	p-values
Demography
Age	32.59 (13.53)	32.48 (13.07)	0.930^d
Gender
Male	107 (78.1%)	30 (21.9%)	0.014^a
Female	69 (63.9%)	39 (36.1%)	0.014^a
Ethnicity
Malay	11 (84.6%)	2 (15.4%)	0.815^b
Chinese	10 (71.0%)	4 (28.6%)
Bumiputera	147 (83.5%)	60 (29.0%)
Indian	0 (0.0%)	0 (0.0%)
Others	8 (72.7%)	3 (27.3%)
Nationality
Malaysian	167 (71.7%)	66 (28.3%)	1.000^b
Non-Malaysian	9 (75.0%)	3 (25.0%)	1.000^b
Symptoms
Duration of symptoms	62.58 (52.46)	82.41 (89.55)	0.559^d
Right iliac fossa pain
Yes	169 (72.5%)	64 (27.5%)	0.327^b
No	7 (58.3%)	5 (41.7%)	0.327^b
Migration of pain
Yes	107 (75.4%)	35 (24.6%)	0.151^a
No	69 (67.0%)	34 (33.0%)	0.151^a
Vomiting
Yes	86 (76.8%)	26 (23.2%)	0.114^a
No	90 (67.7%)	43 (32.3%)	0.114^a
Nausea
Yes	100 (76.9%)	30 (23.1%)	0.060^a
No	76 (66.1%)	39 (33.9%)	0.060^a
Diarrhoea
Yes	57 (76.0%)	18 (24.0%)	0.336^a
No	119 (70.0%)	51 (30.0%)	0.336^a
Dysuria
Yes	17 (81.0%)	4 (19.0%)	0.331^a
No	159 (71.0%)	65 (29.0%)	0.331^a
Anorexia
Yes	121 (79.6%)	31 (20.4%)	0.001^a
No	55 (59.1%)	38 (40.9%)	0.001^a
Past medical history
Comorbidities
Type II Diabetes Mellitus	4 (57.1%)	3 (42.9%)	0.734^b
Hypertension	7 (70.0%)	3 (30.0%)
Ischemic Heart Disease	1 (100.0%)	0 (0.0%)
Others	164 (72.2%)	63 (27.8%)
Numbers of previous abdominal surgeries	0.10 (0.40)	0.16 (0.41)	0.090^d
Factors	Appendicitis		p-value
	Yes (N = 176)	No (N = 69)
Gynaecology history
Menstruating
Yes	14 (66.7%)	7 (33.3%)	0.755^a
No	58 (63.0%)	34 (37.0%)	0.755^a
Dysmenorrhoea
Yes	11 (52.4%)	10 (47.6%)	0.231^a
No	61 (66.3%)	31 (33.7%)	0.231^a
Menstrual cycle
Regular	49 (61.3%)	31 (38.8%)	0.648^a
Irregular	14 (66.7%)	7 (33.3%)	0.648^a
Sexually active
Yes	107 (72.3%)	41 (27.7%)	0.843^a
No	69 (71.1%)	28 (28.9%)	0.843^a
Multiple sexual partners
Yes	4 (100.0%)	171 (71.5%)	0.579^b
No	0 (0.0%)	68 (28.5%)	0.579^b
Vaginal/penile discharge
Yes	4 (50.0%)	4 (50.0%)	0.226^b
No	172 (72.6%)	65 (27.4%)	0.226^b
Physical examination
Right iliac fossa tenderness
Yes	169 (76.8%)	51 (23.2%)	0.000^a
No	7 (28.0%)	18 (72.0%)	0.000^a
Rebound tenderness
None	60 (60.6%)	39 (39.4%)	0.001^b
Light	10 (66.7%)	5 (33.3%)
Moderate	54 (75.0%)	18 (25.0%)
Strong	7 (11.9%)	52 (88.1%)
Guarding
None	78 (59.5%)	53 (40.5%)	0.000^a
Mild	37 (82.2%)	8 (17.8%)
Moderate to severe	61 (88.4%)	8 (11.6%)
Rovsing sign
Yes	36 (87.8%)	5 (12.2%)	0.013^a
No	140 (68.6%)	64 (31.4%)	0.013^a
Temperature	37.00 (0.60)	36.83 (0.42)	0.023^d
Laboratory investigation
Leukocyte count (x 10⁹/L)	16.22 (5.65)	15.10 (6.89)	0.189^c
Leukocyte shift to the left (Neutrophil > 75%)
Yes	123 (76.4%)	38 (23.6%)	0.028^a
No	53 (63.1%)	31 (36.9%)	0.028^a
Factors	Appendicitis		p-value
	Positive (N = 176)	Negative (N = 69)
Polymorphonuclear neutrophils (%)	79.13 (10.93)	73.05 (14.85)	0.003^d
C-reactive proteins (mg/L)	106.53 (100.28)	104.50 (106.80)	0.818^d
URINE FEME
Positive	92 (71.9%)	36 (28.1%)	0.989^a
Negative	84 (71.8%)	33 (28.2%)	0.989^a
^aChi Square ^bFisher Exact ^cIndependent T Test ^dMann Whitney
Continuous variables are presented as Mean (SD)

Laboratory investigations were re-categorized with distinct cutoff values according to respective scoring systems. For an overview, the mean leukocyte count was 15.9 x109/L (SD ± 6.0, range 4.6–44.6 x109/L). 186 participants (75.9%) had leukocytosis (WBC ≥ 11 x109/L). The mean percentage of polymorphonuclear neutrophils was 77.41% (SD ± 12.4, range 26.00–97.2). Mean C-reactive peptide (< 24Hr) was 67.5mg/L (SD ± 87.5, range 0.2-393.9) whereas mean C-reactive peptide (≥ 24Hr) was 118.2mg/L (SD ± 103.3, range 0.2-380.2). When assessed using the RIPASA criterion, 117 (47.8%) samples for urinalysis were free of leukocytes, erythrocytes and nitrite. A total of 94 (38.4%) patients were diagnosed with acute appendicitis while 78 (31.8%) had perforated appendicitis. Another 4 (1.6%) were diagnosed with appendicular abscesses. The incidence of appendicitis was highest in patients within the second to 4th decades of life. Of the 245 patients recruited, 198 (80.8%) received surgery. Histologically, 168 (68.6%) cases were confirmed as appendicitis, whereas the rate of negative appendectomy was 15.2% of those who underwent surgery. Of the 47 patients who did not undergo any surgery, 9 (19.1%) had an ultrasound done and 13 (27.7%) had a CT scan. A total of 25 (53.2%) patients were discharged with a resolution of symptoms without any radiological investigation. There was no recurrence of symptoms among study subjects after discharge within a follow-up period of 3 months.

Sensitivity and specificity analyses were calculated and displayed in Table 2. Original cutoff values of Alvarado, AIR and AAS yielded high specificity but poor sensitivity. The optimal cutoff scores for all systems were lower in this group of participants as calculated with Youden’s Index except for RIPASA which showed a higher optimal score of 8.5. Overall, the scoring systems display moderate sensitivity and specificity at the optimal cutoff point. ROC data are presented in Table 3 and Fig. 1. The RIPASA was shown to be superior in terms of AUC followed by the AAS, AIR and Alvarado scores respectively. However, there was no score shown to be statistically superior to another in sensitivity and specificity, as well as the area under the curve.

Table 2

The analyses of Alvarado, AIR, RIPASA scores and AAS
Scoring System	Sensitivity (95% CI)
Alvarado (1)	97.7 (94.3–99.4)	8.7 (3.3–18.0)	21.1	93.9	6.1
Alvarado (5)^a	69.9 (62.5–76.6)	62.3 (49.8–73.7)	31.7	89.2	10.8
Alvarado (7)^b	25.0 (18.8–32.1)	92.8 (83.9–97.6)	46.3	83.2	16.8
AIR (2)	94.8 (90.5–97.6)	20.3 (11.6–31.7)	22.9	94.1	5.9
AIR (5)^a	76.7 (69.8–82.7)	52.2 (39.8–64.4)	28.6	90.0	10.0
AIR (9)^b	19.3 (13.8–25.9)	92.8 (83.9–97.6)	40.0	82.1	17.9
RIPASA (5.5)	97.2 (93.5–99.1)	13.0 (6.1–23.3)	21.8	94.8	5.2
RIPASA (7.0)	89.2 (83.7–93.4)	37.7 (26.3–50.2)	26.4	93.3	6.7
RIPASA (7.5)^b	84.1 (77.8–89.2)	47.8 (35.6–60.2)	28.7	92.3	7.7
RIPASA (8.5)^a	72.7 (65.5–79.2)	62.3 (49.8–73.7)	32.5	90.1	9.9
AAS (5)	99.4 (96.9–100.0)	10.1 (4.2–19.8)	21.7	98.6	1.4
AAS (8)	92.6 (87.7–96.0)	24.6 (15.1–36.5)	23.5	93.0	7.0
AAS (14)^a	60.2 (52.6–67.5)	75.4 (63.5–84.9)	37.9	88.3	11.7
AAS (16)^b	39.2 (31.9–46.8)	89.9 (80.2–95.8)	49.1	85.5	14.5
^a Optimal cutoff as calculated with Youden’s Index
^b Original cutoff score


Scoring System	AUC	95% CI
Alvarado	0.681	0.619 to 0.739
AIR	0.688	0.626 to 0.745
RIPASA	0.724	0.664 to 0.779
AAS	0.719	0.658 to 0.774

Table 3: The statistical analysis of variables

Simple Logistic Regression

SLR was used to select the best variables to predict the outcomes.

Factors	Crude OR
	p-value (Wald Test)	p-value (LR test)
*Symptoms*
Duration of symptoms	0.038	0.039
Right Iliac Fossa Pain	0.293	0.304
Migration of pain	0.152	0.152
Vomiting	0.115	0.112
Nausea	0.061	0.060
Diarrhoea	0.337	0.331
Dysuria	0.337	0.314
Anorexia	0.001	0.001

*Physical examination*
RIF tenderness	0.000	0.000
Rebound tenderness	0.001	0.001
Guarding
Mild	0.008	0.000
Moderate to severe	0.000	0.000
Rovsing sign	0.017	0.008
Temperature	0.043	0.029

*Lab investigation*
Leukocyte count	0.189	0.183
Leukocyte shift to the left	0.029	0.030
PMF neutrophils	0.001	0.001
CRP	0.913	0.913
UFEME	0.989	0.989

Multiple Logistic Regression

Factors	B	Adjusted OR (95% CI)	p - value
Anorexia	1.021	2.776 (1.191, 6.471)	0.018
RIF tenderness	1.581	4.860 (1.627, 14.518)	0.005
Guarding
Mild	0.950	2.585 (1.015, 6.588)	0.047
Moderate to severe	0.994	2.701 (1.052, 6.936)	0.039

Logistic regression analysis was performed to assess the association of various variables with appendicitis. From the simple logistic regression, variables with a p-value < 0.25 were analyzed in the multiple logistic regression model. Variables discarded included right iliac fossa pain, diarrhoea, dysuria, CRP and UFEME. Having anorexia increases the odds of appendicitis by 2.8 times while controlling other covariates. The patient that manifested tenderness of the right iliac fossa, increases the odds of appendicitis by 4.9 times. If a patient appears to have mild guarding, it increases the chances of appendicitis by 2.6 times and if it appears moderate to severe, the odds are 2.7 times compared to none, by controlling other covariates.

The optimal approach to patients with suspected appendicitis remains debatable. Improvements in access to radioimaging have changed the way this problem is addressed but in many parts of the developing world, the clinical assessment remains the main tool in managing these patients. According to the World Society of Emergency Surgery 2020 Guidelines, appendicitis scoring systems are sufficiently sensitive to exclude appendicitis in low-risk patients and to identify intermediate-risk patients for further investigation which it can reduce the unnecessary usage of imaging and negative appendectomy rates [26]. Therefore, there is a need for a safe and reliable tool in distinguishing patients who fall into the low-risk category, who can be discharged or safely managed in the outpatient setting; from those who will need admission or radioimaging. The rate of false positive and false negative rates of CT scans is 8% and 4% respectively according to a Cochrane study [27]. Studies have shown the use of CT scan in patients with suspected appendicitis to be cost-effective, with or without an ultrasound-first approach. There is however insufficient evidence to distinguish mild appendicitis which can be solely treated with antibiotics while minimizing the risk of recurrence [28]. A routine practice of CT imaging may lead to early diagnosis of low-grade appendicitis and unnecessary appendicectomies, which would otherwise be resolved spontaneously by antibiotic therapy [29].

Our study showed a moderate performance of appendix scoring systems with none significantly with the AAS and RIPASA superior to the Alvarado score. The AUC of RIPASA score was higher than AAS but not statistically significant. The RIPASA score was designed in 2008 using data from patient characteristics in Raja Isteri Pengiran Anak Saleha Hospital. This centre is located in the neighbouring state of Brunei which has a population identical to the current study. This system utilizes 15 simple demographic and clinical parameters to improve the predictive accuracy of appendicitis [18]. The AAS on the other hand is a more recent system created in 2014 and validated in 2017 [20, 21]. It employs the additional use of C-Reactive Peptide as well as advanced statistical analysis to stratify existing parameters according to the risk accorded in order to improve predictive accuracy. Some studies have shown very high sensitivity and specificity of scoring systems whereas others have moderate performance. At the original cut-off limit, all scores except the RIPASA score suffer from poor sensitivity as many appendicitis patients do not achieve the required scores to be classified as high risk using clinical and laboratory criteria. This could lead to false negatives should widespread adoption of the scoring systems be used without strong indigenous data. At higher sensitivity of > 70% (lower cutoff scores), the RIPASA score shows superior (AUC) than the AAS but at higher specificity thresholds (higher cutoff scores) the AAS is superior.

The RIFT Study Group proposed a standard for appendicitis risk prediction models emphasizing high specificity whilst maintaining a Failure Rate (FR) or False Omission Rate of less than 5%. FR is defined as the percentage of patients classified as a low risk who have appendicitis. It is calculated by the formula (False negative/Tested negative); or (100-Negative Predictive Value).(30) Based on our study data, only the AAS was able to demonstrate an FR below 5% (Score 5, FR 1.4%, Specificity 10.1%). However, if an FR of 7% was permitted, the RIPASA score had the highest specificity (Score 7, FR 6.7, Specificity 37.7) followed by AAS (Score 8, FR 7%, Specificity 24.6) and AIR (Score 2, FR 5.9%, Specificity 20.2). The Alvarado score was the least suitable to identify low-risk patients (Score 1, FR 6.1%, Specificity 8.7). This coincides with the findings of the RIFT study group which identified the AAS as the most specific system in ruling out appendicitis.

At present, there is insufficient evidence to support outpatient management of appendicitis with oral antibiotics. From the recent Appendix Accuta (APPAC II) trial, the oral antibiotic regime has failed to show non-inferiority to an IV-plus-oral regime in terms of treatment success rate and 1-year appendectomy rate. Moreover, based on the treatment protocol, the administration of IV antibiotics is required for at least 48 hours. Therefore, only patients with a low risk of appendicitis should be deemed suitable for outpatient management. Without the use of computed tomography, appendicitis risk predictor models could be an option in the developing world [31].

The limitation of this study is that about 10% of patients did not receive any surgery or radiological investigation and were discharged due to the resolution of pain. However, over a 90-day period, there were no patients presenting with recurrent symptoms or requiring surgery. A similar protocol was used by Andersson et al. in the construction of the AIR score [23]. The recurrence rate of patients conservatively treated for appendicitis is around 20% in literature and up to 30% for patients with the presence of appendicolith [32, 33]. Moreover, the selective approach in the usage of imaging modalities did not affect the rate of negative appendectomy in the study. This is pertinent, particularly in the developing world where the benefit of a CT scan is offset by waiting time, which augments the specificity of clinical judgement.

In conclusion, all appendicitis scoring systems demonstrated moderate sensitivity and specificity in risk-stratifying patients with suspected appendicitis. The RIPASA score is more accurate in predicting the presence of appendicitis whereas the AAS was more accurate in risk stratifying patients with low risk of the condition. Optimal population-based cutoff values are crucial for the local adoption of appendicitis scoring systems.

Acknowledgement This study received undivided support from the Department of Surgery, Universiti Kebangsaan Malaysia Medical Centre and Department of Surgery, Queen Elizabeth Hospital, as well as other supporting units which were directly or indirectly involved in this study.

Funding This study received the Universiti Kebangsaan Malaysia Medical Centre Fundamental Research Fund with a code of FF-2020-072.

Conflict of Interest Statement None

Author Contributions Statement D.E.Y.G. wrote the main manuscript text. N.R.K.N.M. and J.A.C. provided the literature review and supervised the research. F.H. involved in final review and manuscript editing. All authors reviewed and agreed with the final manuscript.

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No competing interests reported.

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published 06 Jul, 2023

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Performance and diagnostic accuracy of scoring systems in patients with suspected adult appendicitis

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