Appendicitis Inflammatory Response (AIR) Score

Manne Andersson, MD, is a vascular surgeon in the department of clinical and experimental medicine and the division of surgery, orthopedic and oncology at Linköping University in Linköping, Sweden. Dr. Andersson’s research interests include gangrenous appendicitis and acute appendicitis diagnostic tools.

Why did you develop the AIR Score? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?

In my PhD thesis, I had analyzed the diagnostic properties of clinical variables including laboratory values. I found that the diagnostic importance of clinical variables had been underestimated. In the everyday situation, it is difficult to evaluate the importance and weight of all clinical variables. The score is therefore a way of facilitating and make the clinical diagnosis more objective. It works as a decision support instrument.

What pearls, pitfalls and/or tips do you have for users of the AIR Score? Do you know of cases when it has been applied, interpreted, or used inappropriately?

In diagnosing appendicitis it is most important to identify patients with advanced appendicitis whereas mild appendicitis may resolve spontaneously. The AIR Score is therefore constructed to have high sensitivity for advanced appendicitis. However, patients with short duration of symptoms may have a low score as their immune system has not yet reacted. I therefore recommend rescoring after a few hours in such patients.

What recommendations do you have for doctors once they have applied the AIR Score? Are there any adjustments or updates you would make to the score based on new data or practice changes?

External validation show that the AIR Score works especially well in children and in women, but may be less specific in the elderly. In the elderly, I therefore have a lower threshold for CT scans as there are also more differential diagnoses.

I will underline the importance of the proportion of neutrophils. Advanced appendicitis often has lymphopenia. That is why you can have normal or even low WBC count but then you will always have a high proportion of neutrophils.

I also underline the importance of indirect and rebound (percussion) tenderness which reflects the peritoneal irritation.

How do you use the AIR Score in your own clinical practice? Can you give an example of a scenario in which you use it?

We use the AIR Score as a screening instrument and decision support. A patient with a low score and unaltered general condition can be discharged with a planned reexamination next day.

For an indeterminate score, we admit the patient and do a rescoring after 4-8 hours. Often the diagnosis is more evident then. Sometimes we can do a second rescoring after prolonged observation.

How do you think this score compares with older scores like the Alvarado Score?

The AIR Score is mainly based on objective inflammatory variables and only two subjective variables reflecting peritoneal irritation. The grading of the latter increases the reliability compared with a dichotomous answer (Yes/No). We also used a large set of patients with suspected appendicitis for the design and used a multivariable model with weights aiming at the detection of advanced appendicitis. Other scores are based on more selected patients, have more subjective variables and the weights are based on simpler models.

Any other research in the pipeline that you’re particularly excited about?

By tradition, we think appendicitis needs surgical treatment, but have forgotten that many instances of appendicitis heal spontaneously. With modern diagnostic techniques, we detect more and more of these mild appendicitis. This may explain the current large interest in non-operative treatment with antibiotics. I think this is a mistake. We should not use antibiotics to treat conditions that resolve with no treatment. We need to find ways of defining the prognosis in these cases, and operate those who need treatment and leave the others to resolve. That is my main goal in my current research.

Roland E. Andersson, MD, PhD, is a colorectal surgeon at County Hospital Ryhov in Jönköping, Sweden. He is also a guest professor in the department of clinical and experimental medicine (IKE) at Linköping University in Linköping, Sweden. Dr. Andersson's research interests are primarily related to epidemiology, immunology, and diagnosis of appendicitis, genes associated with colorectal cancer, necrotizing enterocolitis, and risk of cancer and fertility problems associated with chronic inflammatory bowel diseases.