European Journal of Cardiovascular Medicine

Acute appendicitis is a common surgical condition and a frequently suspected differential diagnosis in patients presenting with acute abdominal pain. A systematic analysis from the Global Burden of Disease Study 2019, revealed that in India, at the national level, the age-standardized prevalence rate of appendicitis in 2019 varied from 5.5 cases per 100,000 population, which is 105.6% increase over the ASR rates of 1990. ^[1] The age-standardized incidence of appendicitis in 2019 varied from 149.4 cases per 100,000 population, which is 98.4% increase over the ASR rates of 1990. ^[1] The age-standardized Years lived with Disability (YLDs) due to appendicitis in 2019 varied from 1.7 per 100,000 population, which is 101.4% increase over the ASR rates of 1990. ^[1]

In 1880, Robert Lawson Tait performed the first appendectomy for appendicitis in England ^[2]. Now, more than 140 years later, this most common of all surgical diseases can still be a diagnostic problem. This is demonstrated by the high negative laparotomy rates documented in the literature. A study performed in 2005 in the Netherlands found that approximately 15% of the patients underwent a negative appendectomy, a number

similar to another large Swedish study ^[3]. The negative appendectomy rate was 13% in another large North American study ^[4]. The higher sensitivity of computed tomography (CT) seems to have had an even greater effect on the negative laparotomy rate, which has decreased even further to 5–10% ^{[5, 6]}. In many countries, most surgeons still consider acute appendicitis to be a clinical diagnosis and do not routinely perform imaging studies ^[7].

The management of patients with suspected appendicitis is a subjective synthesis of a large amount of complex information, which relies on the surgeon’s knowledge and previous experience with similar patients. A clinical scoring system can be used as a basis for a structured algorithm for the management of the patients, including selective use of diagnostic imaging depending on the probability of appendicitis. Scoring systems have been designed to aid in the clinical assessment of patients with acute appendicitis.

The Alvarado score is the most well-known and best performing in validation studies, but it has some drawbacks ^[8–10]. Its construction was based on a review of patients who had been operated with suspicion of appendicitis, whereas the score is supposed to be used on all patients with suspicion of appendicitis. Because of the difference in the spectrum of disease between these groups of patients, the scoring weights may be biased ^[13]. The variables were chosen without using an appropriate mathematical model to identify the variables with an independent diagnostic value and to determine their scoring weights. Finally, discriminating capacity was lost because of the dichotomization of the variables.

Appendicitis Inflammatory Response (AIR) score was designed to overcome these drawbacks ^[12]. AIR is a clinical scoring system based on prospectively collected data from patients admitted for suspected appendicitis using an appropriate mathematic model focused on detecting advanced appendicitis. It includes inflammatory markers which have been shown to have high discriminating power ^{[11, 14]}. Instead of dichotomous variables, the clinical variables are graded according to the severity of the symptoms and signs and the laboratory variables are divided into intervals. This score incorporated the C-reactive protein value in its design on a prospective cohort of patients with suspicion of acute appendicitis. Many studies show the importance of C-reactive protein in the assessment of patients with appendicitis ^[11].

Alvarado Score & AIR Score

AIM

The aim of this Study is to compare the Appendicitis Inflammatory Response Score (AIR) score to the traditional Alvarado score to determine which is more accurate in the diagnosis of acute appendicitis.

OBJECTIVE

The objective of the present study is to evaluate the Appendicitis Inflammatory Response score on a consecutive cohort of patients with suspicion of acute appendicitis and compare the AIR score’s performance to the Alvarado score.

Sample

The sample were 50 patients who got admitted and eventually operated upon, during the Study Period, from January 2023 to December 2023 with complaints of Abdominal Pain with provisional diagnosis of Acute Appendicitis, to the Department of Emergency Medicine of Kanyakumari Government Medical College, Nagercoil, Tamil Nadu, India.

Inclusion Criteria

• Patients who give Consent to be included in this study.

Patients with Complaints, History and Clinical Signs & Symptoms pointing towards a provisional diagnosis of Appendicitis

Exclusion Criteria

Patients with GCS less than 15.

• Patients with other surgical causes of abdominal pain (Cholecystitis, Renal Calculi, etc.)
• comorbid to Appendicitis (as evaluated by CT imaging).
• Patients with medical causes of abdominal pain (CLD, MRD, etc.) comorbid to Appendicitis.

Methodology

After documenting detailed history, the patients were clinically examined and evaluated using specified investigations, including plain Computed Tomography (CT), Blood Investigations, Body Temperature, etc. The patients were initially examined by the Resident Surgeons and then by Consultant Surgeons of the Department of General Surgery of Kanyakumari Government Medical College Hospital. Data were collected prospectively on a proforma, completed by the surgical resident who assessed the patient in the Emergency Department. The various parameters in both Alvarado Score and Appendicitis Inflammatory Response Score were documented, and both the Scores were calculated for each patient. Decisions regarding radiological investigations or surgery were at the discretion of the consultant surgeon in charge of the care of the patient. All excised appendices were examined by microscopy. The criterion for appendicitis was histopathologic evidence of transmural inflammation of the appendix specimen. Appendicitis was pathologically diagnosed when infiltration of the muscularis propria by neutrophil granulocytes was seen. ^[15]

Statistical Analysis

Statistical analysis was performed with IBM SPSS statistical software. A p-value of 0.05 was considered statistically significant. One-way ANOVA was used to test if there was statistical significance in the CT findings & each of the Appendicitis Scores and also in the Appendicular Pathology & each of the Appendicitis Scores. The diagnostic performances were assessed on calculated values for sensitivity, and specificity. The area under the Receiver Operating Characteristic (ROC) curves was used to examine the performance characteristics of the two scoring systems. It is generated by plotting Sensitivity on Y axis versus Specificity on X axis at different cut off values. The area under the ROC curve denotes the diagnostic performance of the test, and also a comparison of performance between two tests.

Table 1 Appendicitis Inflammatory Response (AIR) Score

Table 2 Alvarado Score

Table 3 Computed Tomography Impression & AIR Score

ANOVA results gave a F-statistic value = 14.57716, with P-value = 0.00001.

Table 4 Computed Tomography Impression & Alvarado Score

ANOVA results gave a F-statistic value = 13.52988, with P-value = 0.00002.

Table 5 Histo-Pathological Examination & AIR Score

ANOVA results gave a F-statistic value = 15.50014, with P-value = 0.00001.

Table 6 Histo-Pathological Examination & Alvarado Score

ANOVA results gave a F-statistic value = 14.18454, with P-value = 0.00002.

Receiver Operating Characteristic (ROC) curve for AIR Score with Empiric ROC Area = 0.976 and Sensitivity = 97.8% & Specificity = 80%.

Receiver Operating Characteristic (ROC) curve for Alvarado Score with Empiric ROC Area = 0.898 and Sensitivity = 95.6% & Specificity = 60%.

The Computed Tomography (CT) results for every case were categorised into, three categories, viz., ‘Not Appendicitis’, ‘Indefinite’, & ‘Appendicitis’. The Mean AIR Score in each category was calculated. For AIR Score, the ANOVA results gave a F-statistic value = 14.57716, with P-value = 0.00001. Similarly, Mean Alvarado Scores for the same CT results, were calculated. For Alvarado Score, the ANOVA results gave a F-statistic value = 13.52988, with P-value = 0.00002. The ANOVA results are in favour of AIR Score when compared to Alvarado Scores. CT findings correlate more closely with the AIR Scores when compared to the Alvarado Scores, with the P-value of AIR Score (0.00002) being more significant.

The Histo-pathological Examination Results for every case were categorised into, three categories, viz., ‘Not Appendicitis’, ‘Inconclusive’, & ‘Appendicitis’. The Mean AIR Score in each category was calculated. For AIR Score, the ANOVA results gave a F-statistic value = 15.50014, with P-value = 0.00001. Similarly, Mean Alvarado Scores for the same CT results, were calculated. For Alvarado Score, the ANOVA results gave a F-statistic value = 14.18454, with P-value = 0.00002. Here again, the ANOVA results are in favour of AIR Score when compared to Alvarado Scores. HPE findings correlate more closely with the AIR Scores when compared to the Alvarado Scores, with the P-value of AIR Score (0.00002) being more significant.

Comparison of ROC Curves of AIR & Alvarado Scores

The comparison of ROC Curves of AIR & Alvarado Scores show that ROC Curve for AIR Score show an Empiric ROC Area = 0.976, with AIR Score having Sensitivity = 97.8% and Specificity = 80%. ROC Curve for Alvarado Score show an Empiric ROC Area = 0.898, with the Alvarado Score have Sensitivity = 95.6% Specificity = 60%. Receiver Operating Characteristic (ROC) Curves indicate a higher Empiric ROC Area in AIR Score when compared to Alvarado Score, with the Sensitivity & Specificity for AIR Score being greater than Alvarado Score. It is to be noted that for the purpose of generating the ROC Curve, all cases with HPE results of ‘Inconclusive’, was designated, ‘Not Appendicitis’, as HPE results were considered to be the confirmatory diagnosis of Appendicitis. In a study by Castro et al. in 2012, the AIR score recorded a higher sensitivity than the Alvarado score with (93%) and (90%) respectively. In a study done by Patil S et al. in 2017, the AIR score recorded a higher specificity than the Alvarado score with (63.6%) and (54.5%) respectively.

The study results show that both the AIR and Alvarado scores are fairly accurate in assessing the risk of Appendicitis, as the results indicate only marginal but significant differences between the scoring systems, viz., AIR Score & Alvarado Score. When comparing the two scoring systems, the AIR Score performs better than Alvarado Score, in accurately predicting Appendicitis. When the scoring is done and supplemented together with plain Computed Tomography (CT) imaging, it gives an even better accuracy.

The management of patients with suspected acute appendicitis is still challenging, and the optimal management strategy is still unknown, even after the introduction of non-invasive radiological investigations, like Computed Tomography (CT). Many aspects of acute appendicitis have changed in the last 20 years with the advent of minimal access surgery as a diagnostic and a therapeutic procedure as well as increasing use of CT in achieving a pre-operative diagnosis ^[16]. CT has a sensitivity rate of over 95 % and its use has helped reduce negative appendectomy rates ^[17-18]. But, a slide towards routine use of CT for patients with suspected appendicitis is not only unnecessary but also potentially harmful.

This study externally validates that the AIR score has a high discriminating power and outperforms the Alvarado score. This score could aid in selecting patients who require timely surgery or those who require further evaluation. A high specificity, greater than that of the Alvarado score, make it well placed to be used as a decision support tool in identifying patients at high probability of appendicitis that should proceed to surgery. Importantly, the score could safely avoid hospitalization and unneeded investigations in patients in whom the diagnosis is unlikely. In conclusion, the AIR score is a reliable assessment tool that is accurate in assessing the risk of appendicitis.

A randomised control trial should be considered to study the AIR score as grounds for selective use of CT in those deemed with probability for appendicitis. A multi-centre trial with a larger sample size and with randomization & blinding will augment the validity of the study.

Ethical Approval

Ethical Approval Ref. No. S-023/IEC/2022 dated 05-AUG-2022 was obtained from the Institutional Ethical Committee, of the Kanyakumari Government Medical College, Nagercoil, Kanyakumari District, Tamil Nadu, India.

Conflicts of Interest

The authors have no conflicts of interest to declare.

Financial Assistance

The authors declare that no funding was received for this study.

1. Guan, L, et al.The global, regional, and national burden of appendicitis in 204 countries and territories, 1990–2019: a systematic analysis from the Global Burden of Disease Study 2019. BMC Gastroenterol 23, 44 (2023). https://doi.org/10.1186/s12876-023-02678-7.
2. Seal A. Appendicitis: a historical review. Can J Surg. 1981 Jul;24(4):427-33. PMID: 7023636.
3. Andersson RE, Hugander A, Thulin AJ. Diagnostic accuracy and perforation rate in appendicitis: association with age and sex of the patient and with appendicectomy rate. Eur J Surg. 1992 Jan;158(1):37-41. PMID: 1348639.
4. Hale DA, Molloy M, Pearl RH, Schutt DC, Jaques DP. Appendectomy: a contemporary appraisal. Ann Surg. 1997 Mar;225(3):252-61. doi: 10.1097/00000658-199703000-00003. PMID: 9060580
5. SCOAP Collaborative; Cuschieri J et al, Negative appendectomy and imaging accuracy in the Washington State Surgical Care and Outcomes Assessment Program. Ann Surg. 2008 Oct;248(4):557-63. doi: 10.1097/SLA.0b013e318187aeca. PMID: 18936568.
6. Wagner PL et al. Defining the current negative appendectomy rate: for whom is preoperative computed tomography making an impact? Surgery. 2008 Aug;144(2):276-82. doi: 10.1016/j.surg.2008.03.040. PMID: 18656636.
7. Poortman P, Oostvogel HJ, de Lange-de Klerk ES, Cuesta MA, Hamming JF. The use of imaging in the case of suspected acute appendicitis: opinion of Dutch surgeons. Ned Tijdschr Geneeskd. 2009;153:B376. Dutch. PMID: 19785840.

8. Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986 May;15(5):557-64. doi: 10.1016/s0196-0644(86)80993-3. PMID: 3963537.
9. Owen TD, Williams H, Stiff G, Jenkinson LR, Rees BI. Evaluation of the Alvarado score in acute appendicitis. J R Soc Med. 1992 Feb;85(2):87-8. doi: 10.1177/014107689208500211. PMID: 1489366
10. Douglas CD, et al. Randomised controlled trial of ultrasonography in diagnosis of acute appendicitis, incorporating the Alvarado score. BMJ. 2000 Oct 14;321(7266):919-22. doi: 10.1136/bmj.321.7266.919. PMID: 11030676
11. Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Br J Surg. 2004 Jan;91(1):28-37. doi: 10.1002/bjs.4464. PMID: 14716790.
12. Andersson M, Andersson RE (2008) The appendicitis inflammatory response score: a tool for the diagnosis of acute appendicitis that outperforms the Alvarado score. World J Surg. 2008 Aug;32(8):1843-9. doi: 10.1007/s00268-008-9649-y. PMID: 18553045.
13. Ransohoff DF, Feinstein AR. Problems of spectrum and bias in evaluating the efficacy of diagnostic tests. N Engl J Med. 1978 Oct 26;299(17):926-30. doi: 10.1056/NEJM197810262991705. PMID: 692598.
14. Andersson RE, et al. Diagnostic value of disease history, clinical presentation, and inflammatory parameters of appendicitis. World J Surg. 1999 Feb;23(2):133-40. doi: 10.1007/pl00013174. PMID: 9880421.
15. Marudanayagam R, Williams GT, Rees BI. Review of the pathological results of 2660 appendicectomy specimens. J Gastroenterol. 2006 Aug;41(8):745-9. doi: 10.1007/s00535-006-1855-5. PMID: 16988762.
16. Sporn E, et al. Laparoscopic appendectomy--is it worth the cost? Trend analysis in the US from 2000 to 2005. J Am Coll Surg. 2009 Feb;208(2):179-85.e2. doi: 10.1016/j.jamcollsurg.2008.10.026. PMID: 19228528.
17. Anderson BA, Salem L, Flum DR. A systematic review of whether oral contrast is necessary for the computed tomography diagnosis of appendicitis in adults. Am J Surg. 2005 Sep;190(3):474-8. doi: 10.1016/j.amjsurg.2005.03.037. PMID: 16105539.
18. Krajewski S, Brown J, Phang PT, Raval M, Brown CJ. Impact of computed tomography of the abdomen on clinical outcomes in patients with acute right lower quadrant pain: a meta-analysis. Can J Surg. 2011 Feb;54(1):43-53. doi: 10.1503/cjs.023509. PMID: 21251432