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AIR Score

Appendicitis Inflammatory Response Score — Swedish Validation 2008

A 12-point evidence-based scoring system incorporating CRP and refined rebound tenderness grading. Outperforms the Alvarado score in prospective Swedish and international validation studies.

General Surgery Acute Abdomen Appendicitis
AIR Score Calculator
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AIR Score (out of 12)
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Score Interpretation

ScoreRiskRecommended Action
0–4 Low (NPV ~97%) Discharge with advice; no imaging needed
5–8 Intermediate CT scan or active observation; surgical review
9–12 High (PPV ~93%) Proceed to surgery or diagnostic laparoscopy

Clinical Application

  • AIR Score was derived and validated in Sweden (2008) across multiple emergency surgical units
  • Key advantage: inclusion of CRP (superior to WBC alone) and graded rebound tenderness
  • Low score (0–4): negative predictive value ~97% — safe for discharge
  • Intermediate (5–8): CT abdomen/pelvis is the preferred next step; allows detection of perforated appendicitis
  • High score (9–12): positive predictive value ~93% — proceed directly to theatre or diagnostic laparoscopy
  • Superior to Alvarado in female patients and in cases where CRP is elevated without significant leukocytosis
  • Combine with clinical gestalt; a rising CRP over 6–12 hours further increases suspicion in intermediate-risk patients

Formula

Total = Vomiting (0/1) + RIF pain (0/1) + Rebound tenderness (0–3) + Temp ≥38.5°C (0/1) + PMNs (0–2) + WBC (0–2) + CRP (0–2)

Range: 0–12

References

  1. Scott AJ, et al. Prospective validation of the Appendicitis Inflammatory Response score. Br J Surg. 2015.
  2. de Castro SMM, et al. Appendicitis Inflammatory Response (AIR) score. World J Surg. 2012.
  3. 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;32(8):1843–1849.

Related Calculators

Alvarado Score RIPASA Score BISAP Score