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Year : 2019  |  Volume : 32  |  Issue : 2  |  Page : 544-548

Reliability of the adult appendicitis score in diagnosing acute appendicitis

Department of General Surgery, Faculty of Medicine, Menofia University, Menoufia, Egypt

Date of Submission07-Jan-2018
Date of Acceptance03-Mar-2018
Date of Web Publication25-Jun-2019

Correspondence Address:
Mohannad H Abuomar
Flat 21, Building 19, Group 18, Madinaty, Cairo
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mmj.mmj_914_17

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Appendicitis is a common cause of abdominal pain. Nevertheless, diagnosis of acute appendicitis is still a challenge, with the hazards of either negative appendectomy or complicated appendicitis. Using an optimum scoring system, such as adult appendicitis score (AAS), can increase the diagnostic accuracy eliminating the need for potentially harmful and costly imaging studies.
The aim was to test the reliability of AAS in diagnosis of acute appendicitis.
Settings and design
This was a prospective, noninterventional study in the emergency department of Menoufia University hospitals.
Patients and methods
Eligible patients who presented with right lower quadrant pain in the period from January 2016 to April 2017 were enrolled in the study. History taking, clinical examination, and laboratory testing (white cell count, neutrophil count, and C-reactive protein) were carried out to test the reliability of the AAS, and it was compared with the Alvarado score and appendicitis inflammatory response score. Sensitivity and specificity, as well as negative and positive predictive values were calculated for each score. Correlation analysis was conducted between each score results and final pathological results. Receiver operating characteristic curves were plotted to estimate the reliability.
AAS was the most specific one at score 16, with specificity 97.9% and positive and predictive value 97.4%, whereas the appendicitis inflammatory response score was the most sensitive at score 5, with sensitivity and negative predictive values of 100%. Using the receiver operating characteristic curves showed the AAS was the most reliable, with area under the curve of 0.936 (P = 0.00).
AAS is a reliable score to risk stratify patients with suspected acute appendicitis, guiding only intermediate-risk cases to further imaging. At score greater than or equal to 18, cases can be directed confidently to surgery without delay.

Keywords: abdominal pain, acute appendicitis, adult appendicitis score, appendicitis score

How to cite this article:
Elshakhs S, Abdelsamie M, Fareed A, Abuomar MH. Reliability of the adult appendicitis score in diagnosing acute appendicitis. Menoufia Med J 2019;32:544-8

How to cite this URL:
Elshakhs S, Abdelsamie M, Fareed A, Abuomar MH. Reliability of the adult appendicitis score in diagnosing acute appendicitis. Menoufia Med J [serial online] 2019 [cited 2020 May 25];32:544-8. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/544/260941

  Introduction Top

Appendicitis represents a common cause of abdominal pain, which is in turn a leading presenting symptom among care seekers in emergency departments[1], with a lifetime risk of 9% of the population[2]. It mostly occurs in adolescents and young adults, with slight sex-related incidence discrepancy, as men are more affected than women[3].

Considering the malpractice claims for practicing emergency physicians, missed appendicitis comes third after missed myocardial infarction and fractures[4], and this clearly reflects the dilemma in diagnosis of appendicitis, especially in women in childbearing period, old people, and those with atypical presentations[3].

On the one hand, the delay in diagnosis of appendicitis, by caused either observation in equivocal cases or time-consuming investigations in straightforward diagnoses, can lead to complications such as perforation with increased morbidity and mortality[5]. On the other hand, negative appendectomy rate is estimated to be approximately 15–30%, particularly in cases operated based on a clinical decision[6], and this is not costless and a safe procedure, but causes an early complication rate of 7–13%[7].

In modern practice, the imaging study of choice for suspected appendicitis in adults is computed tomography (CT)[8], which reduced negative appendectomy rates to less than 10%. Nevertheless, a single exposure to CT on the abdomen and pelvis has an additional cancer risk of 0.2% in a 30-year-old healthy person. Given this fact, making the imaging has an enduring cost[9].

With the aim to overcome these challenges, different scoring systems have been proposed. A common feature of these scores is to combine symptoms, signs, and laboratory results to classify the patients into categories[10].

Alvarado score and appendicitis inflammatory score (AIS) are commonly used ones. However, their reliability is still questionable. In 2014, Sammalkorpi et al.[11]published a newly constructed score, the adult appendicitis score (AAS), with promising results.

In this study, we aimed at comparing the reliability of the AAS versus the Alvarado and AIS. This should yield a well-structured clinical guidance in the emergency service, with subsequent better outcomes and less cost[11].

  Patients and Methods Top

Over 16 months from January 2016 to April 2017, eligible patients older than or equal to 16 years who presented to the emergency service of Menoufia University hospital with right lower quadrant (RLQ) pain were enrolled in the study. The research protocol was approved by the IRB of Menoufia Faculty of Medicine.

Emergency physicians calculated the AAS, the AIS [appendicitis inflammatory response (AIR)], and the Alvarado score during the initial examination at the Emergency Department. The collected data included clinical signs (tenderness in RLQ, guarding in RLQ, and body temperature) and symptoms (pain in RLQ, migration of pain, vomiting, and anorexia), together with laboratory test results [C-reactive protein (CRP), total leukocyte count, and proportion of neutrophils], as well as time elapsed between the onset of symptoms to presentation. No scoring systems guided the surgeon's decision to operate.

All surgically removed appendices were sent for histopathological examination, along with a detailed report. Labeling a case as 'positive appendicitis' was confirmed when pathological examination showed transmural infiltration with neutrophils in the appendix.

For each candidate in the study, the Alvarado and AIR scores were calculated and compared with AAS utilizing the pathologically based final diagnosis. Scoring less than or equal to 11 in AAS was classified as low risk, 12–15 as intermediate risk, and greater than or equal to 16 as high risk.

For each score, sensitivity and specificity, as well as positive and negative predictive values (PPV and NPV) were determined. Correlation analysis was conducted using receiver operating characteristic (ROC) analysis with determination of the area under the ROC curve for each score.

  Results Top

The study included 100 patients, with 50 males and 50 females, who presented with RLQ pain to the emergency service of Menoufia University Hospital over 16 months from January 2016 to April 2017. Their mean age was 32.1 ± 16.5 years. Baseline characteristics of the enrolled patients are illustrated in [Table 1].
Table 1: Patients' characteristics

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The clinical diagnosis established by physicians was correlated to the pathological findings. Of 100 patients, 68 patients were true positive (as confirmed with pathology), whereas 32 patients were true negative. In contrast, five were false positive and four were false negative. Among the true-positive cases, one case was owing to parasitic infestation.

Concerning the AAS; we assessed this score based on the following [Table 2]: at score 11, the sensitivity of the AAS was 94.1%, the specificity was 84.4%, the PPV was 92.8%, and the NPV was 87.1%. At score 16, the sensitivity of the AAS was 54.4%, the specificity was 97.9%, the PPV was 97.4%, and the NPV was 50%. At score 18, the sensitivity of the AAS was 29.4%, the specificity was 100%, the PPV was 100%, and the NPV was 40%. Area under the curve (AUC) was 0.936 (P = 0.00; [Table 3] and [Figure 1]).
Table 2: Adult appendicitis score at cut-off points 11, 16, and 18

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Table 3: Alvarado score at cut-off points: 5 and 7

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Figure 1: Receiver operating characteristic curve of adult appendicitis score. ROC curve, receiver operating characteristic curve.

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Concerning the Alvarado score, we assessed this score at different cut-off points. At score 5, the sensitivity of the Alvarado score was 97.1%, the specificity was 56.3%, the PPV was 82.5%, and the NPV was 90%. At score 7, the sensitivity of the Alvarado score was 50%, the specificity was 87.5%, the PPV was 89.5%, and the NPV was 45.2%. AUC was 0.845 (P = 0.00; [Table 4]).
Table 4: Appendicitis inflammatory score at points 5 and 8

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Concerning AIR score, we assessed this score based on the following: at score 5, the sensitivity of the AIR score was 100%, the specificity was 46.9%, the PPV was 80%, and the NPV was 100%. At score 8, the sensitivity of the AIR score was 70.6%, the specificity was 93.8%, the PPV was 96%, and the NPV was 60%. AUC was 0.926 (P = 0.00; [Table 5]).
Table 5: Adult appendicitis score

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  Discussion Top

Appendicitis represents a common cause of abdominal pain which in turn is a leading presenting symptom among care seekers in emergency departments[9]. Different scores have been proposed and investigated to avoid missing cases and accurately establish a diagnosis[12]. Of these scores, the most commonly used are the Alvarado score, the AIR score, and the recently constructed AAS.

Overall, labeling a patient with RLQ pain as having acute appendicitis, even if utilizing the conservative approach with antibiotics, must be supported by a solid diagnosis as recommended by Styrud et al.[13] who recommended the use of CT and/or ultrasound in the context of elevated CRP, and this goes in line with the American College of Emergency Physicians level B recommendation in patients with suspected acute appendicitis to use clinical findings to risk stratify patients and guide decisions about further testing and management[1].

Alvarado score was constructed by a retrospective study of 305 hospitalized patients with abdominal pain suggestive of acute appendicitis, relying upon localized tenderness in the RLQ, leukocytosis, migration of pain, shift to the left, temperature elevation, nausea vomiting, anorexia-acetone, and direct rebound pain[14].

The AIR score was described by Andersson and Andersson[15] prospectively based on 545 patients admitted for suspected appendicitis at four hospitals. The score entails eight variables with independent diagnostic value (RLQ pain, rebound tenderness, muscular defense, white blood cells count, proportion neutrophils, CRP, body temperature, and vomiting)[16].

The AAS was constructed by Sammalkorpi et al.[11] through a prospective study that enrolled 829 adults presenting with clinical suspicion of appendicitis, including 392 (47%) patients with appendicitis. The collected data included clinical findings and symptoms together with laboratory tests (white cell count, neutrophil count, and CRP), and the timing of the onset of symptoms[11].

In the current study, we aim at comparing the predictive values and the accuracy of these scores. A total of 100 patients with RLQ pain enrolled after assessment for symptoms, signs, and laboratory tests. Operated patients had the diagnosis made by histopathological examination, whereas nonoperated ones were followed up for 2 weeks for attendance with acute appendicitis/complication.

In the present study, the sensitivity, the specificity, the PPV, and the NPV for the AAS were 94.1, 84.4, 92.8, and 87.1%, respectively; 54.4, 97.9, 97.4, and 50%, respectively; and 29.4, 100, 100, and 40%, respectively, at cut-off points 11, 16, and 18, respectively. This is in agreement with Sammalkorpi et al.[11] who reported sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 95.9, 54.2, 2.1, and 0.076%, respectively; 58.0, 92.7, 7.9, and 0.45%, respectively; and 27.7, 97.6, 11.5, and 0.74%, respectively, at scores 11, 16, and 18, respectively. In terms of specificity 97.9 & 100% and PPV 97.4 & 100% at cut-off points 16 and 18, respectively, of the studied AAS, it is worth noting that it outperformed the combined use of Alvarado score and diagnostic laparoscopy in comparison to the results of Lamparelli et al.[17], where specificity and PPV were 95 and 90%, respectively. Moreover, the AAS score had better sensitivity and specificity than ultrasonography, which was in line with Ozkan et al.[18] who reported that sensitivity was 71.2, specificity was 46.7%, the PPV was 82.2%, the NPV was 31.8%, and the accuracy rate was determined as 65.7%. The sensitivity of tomography was determined as 97.2%, the specificity as 62.5%, PPV as 92.1%, and NPV as 83.3%, and the accuracy rate was determined as 90% which outperformed the AAS score in the same study as previously mentioned[18].

In the present study, for the Alvarado score, the sensitivity was 97.1 and 50%, the specificity was 56.3 and 87.5%, PPV was 82.5 and 89.5%, and NPV was 90 and 45.2% at scores 5 and 7, respectively. This is in agreement with Ohle et al.[19], who reported the cut-off point of 5 was good at 'ruling out' admission for appendicitis (sensitivity of 99% overall, 96% for men, 99% for woman, and 99% for children). At the cut-off point of 7, which is recommended for 'ruling in' appendicitis and progression to surgery, the score performed poorly in each subgroup (specificity: overall 81%, men 57%, woman 73%, and children 76%)[19]. This is also in agreement with Kollár et al.[20] who reported sensitivity values of 79 and 93% and specificity of 76 and 55%, PPV of 65 and 54%, and NPV of 86 and 93% for high and low probability appendicitis classified by the Alvarado score and Ozkan et al.[18] who reported the sensitivity of the Alvarado score as 54%, the specificity as 73.3%, the PPV as 88.2%, and the NPV as 29.7%, and the accuracy rate was determined as 57.7%. In contrast, McKay and Shepherd[21] reported lower values (the sensitivity of equivocal Alvarado scores, defined as scores of 4 to 6, for acute appendicitis was 35.6% and the specificity 94%). Moreover, Mán et al.[2] in 2014 reported lower values of sensitivity (69%) and specificity (87.8%). McKay and Shepherd[21] reviewed 150 medical records to develop guidelines for CT scanning based on Alvarado scoring. Overall, 5% of patients with scores of 3 or less had appendicitis, 36% of patients with scores between 4 and 6 had appendicitis, and 78% of patients with scores of 7 or higher had appendicitis. The authors concluded that patients with scores of 3 or less should not have CT[21]. In a class III study, Gwynn[22] found that 12 (8.4%) of 143 participants with appendicitis had Alvarado scores less than 5. Patients in extremes of age (60–80 and 0–10 years of age) were misdiagnosed more frequently[22]. In a small class III study, Yildirim et al.[23] found that 72% of patients with Alvarado scores between 1 and 4 ultimately had appendicitis, according to CT results and subsequent surgery.

In the present study, the sensitivity of the AIR score was 100 and 70.6% and the specificity was 46.9 and 93.8%, the PPV was 80 and 96%, and the NPV 100 and 60% at scores 5 and 8, respectively. This is in agreement with Kollár et al.[20] who reported sensitivity, specificity, PPV, and NPV: 94 & 33%; 62 & 97%; 59 & 88%; and 95 & 71%. On the contrary, Patil et al.[24] reported a lower sensitivity and a higher specificity (89.9 and 63.6, respectively) at score 5.

  Conclusion Top

We concluded that the scores differ in their accuracy and reliability. In our study, AIS score was the most sensitive one, where AAS was the most reliable, as ROC shows. Moreover, AAS was the most specific and thus the most useful to rule out a diagnosis. That is why different scores should be applied in the emergency room (ER), so as not to rely on one score. Further work is required to establish a well-agreed clinical guidance for appendicitis management.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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