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Appendicitis Inflammatory Response (AIR) Score

Calculators  Gastrointestinal
The Appendicitis Inflammatory Response Score (AIR) calculator is a tool that helps diagnose appendicitis based on clinical and laboratory findings in pediatric or adult patients with suspected appendicitis.
No 0
Yes 1
Right inferior fossa pain
No 0
Yes 1
Rebound tenderness
None 0
Light 1
Medium 2
Strong 3
Temperature ≥101.3ºF (38.5ºC)
No 0
Yes 1
Polymorphonuclear Leukocytes Number
<70% 0
70-84% 1
≥85% 2
White Blood Cell Count, *10⁹/L
<10 0
10.0-14.9 1
≥15 2
C-reactive Protein Level
<10 0
10-49 1
≥50 2


Measured Factor
Risk or likelihood of having appendicitis.
Measured Factor Disease
  • AIR scores ≥ 9 indicates a high risk for appendicitis, thus requiring surgica intervention.
Measured Factor Detail
The Appendicitis Inflammatory Response (AIR) score is a stratification system that helps healthcare providers determine a patient's likelihood of appendicitis after presenting with suspected symptoms. This score takes into consideration 7 items; presence of vomiting, right inferior fossa pain, rebound tenderness, temperature ≥ 101.3ºF, polymorphonuclear leukocytosis, white blood cell (WBC) count, and the level of C-reactive protein present. Items are given a score of 0, 1, 2 or 3 and the addition of these scores determines the patient's risk. Patients with scores between 0 and 4 are deemed low risk and only require outpatient follow up, patients with scores between 5 and 8 have intermediate risk and should be under observation with serial re-exams, diagnostic laparoscopy or imaging. Lastly, patients with scores between 9 and 12 have a high risk and require surgical exploration.
Body System
Measured Factor Low Impact
  • AIR score ≤ 4 indicates low risk of appendicitis.
Measured Factor High Impact
  • AIR scores ≥ 9 indicates a high risk for appendicitis.

Result Interpretation

Ranges Ranges
  • Critical High: Score ≥ 9
  • Normal: Scores 0
  • Normal Adult Male: Score 0
  • Normal Adult Female: Score 0
  • Normal Pediatric: Score 0
  • Normal Geriatric Male: Score 0
  • Normal Geriatric Female: Score 0
Result High Conditions
  • Appendicitis


Study Validation 1
Retrospective study assesing the validity of the appendicitis inflammatory response (AIR) score and comparing it to the Alvarado score, a more well known stratification system for the confirmation of appendicitis. Study consisted of patients who presented to the emergency department between 2006 and 2009 with symptoms of appendicitis. All the variables necessary for calculation of both scores were collected and included variables like nausea, vomiting, anorexia, migration of pain to the right lower quadrant, rebound tenderness, muscular defence, body temperature, high white blood cell (WBC) count, proportion of polymorphonuclear leukocytosis and levels of C-reactive protein. Statistical analysis was performed and a p value < 0.05 was considered significant. Pearson's chi-square test was used and the area under the receiver operating characteristi (ROC) curves was used to examine the performance of both scoring systems. The study included a total of 941 patients; the ROC was 0.96 for the AIR score and 0.82 for the Alvarado score (p < 0.05). Investigators concluded that the AIR score for patients with acute appendicitis had a high discriminating power and was better than the Alvarado score.
References: 2
Study Validation 2
Retrospective study evaluating the appendicitis inflammatory response (AIR) score, Alvarado score and the Pediatrics appendicitis  (PAS) score in children suspected of acute appendicitis. Because of the diagnostic difficulty various scoring systems have been developed; the Alvarado score has been validated for use in patients of all ages, while PAS is only intended for children and adolescents. The more recently developed AIR score was constructed for adults and its use has been validated in the prediction of acute appendicitis. All of these scores take into account similar factors, but the AIR score differs in its use of the C-reactive protein (CRP). All patients included in the study were children younger than 18 years of age that presented to the emergency rooms with suspected acute appendicitis between 2006 and 2014. All values necessary for calculating the 3 scores was obtained and their diagnostic performance was evaluated using the area under the receiver-operating curve (AUROC) and calculating their diagnostic performance at different points. The cutoffs were as followed; for the AIR score there was a low (0-4), intermediate (5-8) and high (9-12), for the Alvarado score it was low (0-4), intermediate (5-6), likely (7-8) and highly likely (9-10), the PAS score was simply divided into low (≤5) and high (≥6). The study included a total of 747 children, of which 269 were diagnosed with acute appendicitis. The AUROC for the AIR score was 0.9, for the Alvarado score it was 0.87 and for the PAS it was 0.82 (p<0.05). The specificity of the AIR score at predicting appendicitis was better than the other scores. Overall, the AIR demonstrated higher discriminating power than the Alvarado and PAS scores in predicting acute appendicitis in children.
References: 3
Study Validation 3
Randomized clinical trial analyzing the impact of implementing a risk stratification algorithm based on the Appendicitis Inflammatory Response (AIR) score compared to traditional imaging for diagnosis of appendicitis. Patients age 5 years or older were included in the study if they presented to an emergency room with suspected acute appendicitis between 2009 and 2012. The AIR score-based algorithm was implemented during the intervention period and patients with intermediate risk were randomized to undergo either routine or selective imaging. A total of 2639 patients were in the intervention period and 1068 were intermediate-risk and this randomized for different imaging. In patients with low risk, the AIR score based algorithm resulted in less imaging (19.2% vs. 34.5%, p < 0.001), fewer admissions (29.5% vs. 42.8%, p<0.001), fewer negative explorations (1.6% vs. 3.2%, p = 0·030), and fewer operations for non-perforated appendicitis (6.8% versus 9.7%, p = 0·034). Patients who were intermediate risk and randomized to different imaging showed no difference in outcomes, they had the same proportion of negative appendicectomies, admissions, perforations and length of hospital stay. However, these intermediate-risk patients with routine imaging were more likely to be treated for appendicitis (53.4% vs. 46.3%, p = 0·020). Overall, the AIR score was shown to safely reduce the use of diagnostic imaging and hospital admissions.
References: 4
Study Additional 1
Retrospective study evaluating the appendicitis inflammatory response (AIR) score and comparing its performance to the Alvarado score and with the clinical impressions of a senior surgeon in prediciting risk of appendicitis. The Alvarado score and the AIR score utilize the same principles for assigning patients to low, medium or high probability of acute appendicitis, however the AIR score takes into consideration the level of C-reactive protein present (CRP). In addition to the scores, a senior resident or consultant surgeon was asked to categorize each patient into a low, medium or high risk probability group for acute appendicitis. For analysis, all predictions were correlated with the final diagnosis of appendicitis. Results showed that 67 patients out of 182 had a final diagnosis of appendicitis (37%) with all three methods stratifying similar proportions of patients to low probability groups (p=0.2333). The AIR score showed higher specificity (97%) compared to the Alvarado score.  The AIR score assigned a smaller proportion of patients to the high probability zone than the Alvarado score (14% vs. 45 %) but it did so with a substantially higher specificity (97 %) and positive predictive value (88 %) than the Alvarado score (76% vs. 65 %, respectively). Overall, the AIR score was shown to be accurate at excluding appendicitis in patients with low risk and even more accurate at predicting appendicitis in those deemed high risk when compared to the Alvarado score.
References: 5
Study Additional 2
Retrospective study evaluating the utility of the Appendicitis Inflammatory Response (AIR) score as a tool for diagnosing and predicting the severity of acute appendicitis. The score contributes to diagnosis by associating applicable clinical criteria and two laboratory tests. Patients with all available data to calculate AIR scores were included in the study and descriptive statistics was used, incuding absolute simple frequencies, percentage and descriptive measures (mean, medium, standard variation, etc.). Statistical significance was set at p<0.05. The AIR score criteria was on average 7.7 and all patients were placed in subgroups as mild (65.3%) and high (34.7%) probability for acute appendicitis. Results also showed that patients with scores for high probability also had statistically significant chance of showing more developed stages of acute appendicitis. C-reactive protein and percentage of leukocytes segmented blood count showed a direct relationship with acute appendicitis. Overall, the results indicated that laboratory data taken into account in the AIR score were important factors for diagnosis and disease stratification.
References: 6
Study Additional 3
Prospective observational study assesing the benefits of the Appendicitis Inflammatory Response (AIR) score in guiding clinical decision-making. The study took place over a 50 week period, during which all patients admitted with suspected appendicitis had AIR scores calculated. Confirmation of diagnosis was performed by histological examination and patients were stratified as having appendicitis or not. Descriptive statistics was used to compare results and utility of the AIR score. A total of 464 patients were included in the study of whom 210 had non-appendicitis pain and were correctly placed into the low risk category by the AIR score. AIR scores of 5 or more (intermediate or high risk classification) showed high sensitivity for all severities of appendicitis (90%). AIR scores of 9 or more (classified as high risk) had even greater specificity (97%) for appendicitis. Results demonstrated that risk stratification using the AIR score could guide decision making in order to reduce unnecessary admissions and optimize treatment.
References: 7


Manne Anderson, MD, is a vascular surgeon at Linköping University in Linköping, Sweden. Research interests include gangrenous appendicitis and acute appendicitis diagnostic tools
Roland E. Anderson, MD, PhD, is a colorectal surgeon at County Hospital Ryhov in Jönköping, Sweden. He is also a professor in the department of clinical and experimental medicine and the division of surgery, orthopedics and oncology at the Linköping University in Linköping, Sweden. Research interests are primarily focused on appendicitis and the colon


  1. Andersson M, Andersson RE. 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.
  2. de Castro SM, Ünlü C, Steller EP, van Wagensveld BA, Vrouenraets BC. Evaluation of the appendicitis inflammatory response score for patients with acute appendicitis. World J Surg. 2012 Jul;36(7):1540-5.
  3. Macco S, Vrouenraets BC, de Castro SM. Evaluation of scoring systems in predicting acute appendicitis in children. Surgery. 2016 Dec;160(6):1599-1604.
  4. Andersson M, Kolodziej B, Andersson RE; STRAPPSCORE Study Group. Randomized clinical trial of Appendicitis Inflammatory Response score-based management of patients with suspected appendicitis. Br J Surg. 2017 Oct;104(11):1451-1461.
  5. Kollár D, McCartan DP, Bourke M, Cross KS, Dowdall J. Predicting acute appendicitis? A comparison of the Alvarado score, the Appendicitis Inflammatory Response Score and clinical assessment. World J Surg. 2015 Jan;39(1):104-9.
  6. Von-Mühlen B, Franzon O, Beduschi MG, Kruel N, Lupselo D. AIR score assessment for acute appendicitis. Arq Bras Cir Dig. 2015 Jul-Sep;28(3):171-3.
  7. Scott AJ, Mason SE, Arunakirinathan M, Reissis Y, Kinross JM, Smith JJ. Risk stratification by the Appendicitis Inflammatory Response score to guide decision-making in patients with suspected appendicitis. Br J Surg. 2015 Apr;102(5):563-72.

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