Often the Ped EM Morsels discuss diagnoses that emphasize astute clinical skills and vigilance while minimizing the importance of laboratory testing. Appendicitis is a great example of this!

Many of you already know my disdain for the ubiquitous WBC count (otherwise known as the “Last Bastion of the Intellectually Destitute” – Amal Mattu) and are also aware of the many Myths that are associated with Appendicitis. This month’s Annals of Emergency Medicine (2014, Oct; 64(4)) addresses another often encountered issue with Appendicitis: the Clinical Decision Rules.

Clinical Decision Rules

The practice of medicine is becoming more complicated everyday.

Ideally, we would like to ensure that all patients get superior care regardless of where they receive their care.

Clinical Decision Rules are aimed at helping providers deliver consistent and high quality care.

Clinical Decision Rules integrate various features (history, exam, simple labs, etc) in an effort to predict the likelihood of a specific disease/condition .

. Useful Clinical Decision Rules would stratify patients into Low, Moderate, and High Risk Groups. Low Risk – Condition ruled-out. No testing. Moderate Risk – “Test Threshold” – Requires further testing. High Risk – “Treatment Threshold” – Condition ruled-in. No Testing… just treat!



Appendicitis and Clinical Decision Rules

There are two widely used Clinical Decision Rules for Appendicitis. Alvarado Score Pediatric Appendicitis Score

The Alvarado Score has been found to have better test characteristics than the Pediatric Appendicitis Score (although they vary only slightly).

The Alvarado Score is a 10-point Score: 1 point for – Migration of Pain Anorexia Nausea or vomiting Rebound Pain Elevated Temperature (greater than or equal to 99.2 F) Left Shift (greater than or equal to 75% PMNs) 2 points for – Right Lower Quadrant Tenderness Leukocytosis (greater than or equal to 10,000/microL).



The Pediatric Appendicitis Score gives only 1 point for leukocytosis and gives no points for rebound pain while adding 2 points for RLQ pain with coughing, jumping, percussion.

Unfortunately, often theses clinical findings are not reliably reproduced (we all know if the ask a patient a question 3 times you’ll get at least 2 different replies – “Did you vomit?” “No.” “Did you vomit?” “No.” “Did you vomit?” “Oh, you mean throw up? Yes I did.”).

Pretest Probability Matters

The Ebell and Shinholser paper nicely demonstrates the fact that the performance of the Clinical Decision Rule for appendicitis is dependent upon the pretest probability . At a pretest probability of 33%, even an Alvarado Score of 9 or 10 does not cross the Treatment Threshold . At a pretest probability of 66%, even an Alvarado Score of <4 does not define a useful Low Risk group .

. What determines the clinician’s Pretest Probability?? While clinical experience and illness scripts certainly play a role in the estimation of the Pretest Probability,… I would also suggest that the Clinical Variables scored in the Clinical Decision score play a significant role in the determination of a Pretest Probability . So if a patient has migratory pain, nausea/vomiting, fevers, RLQ tenderness and rebound, both the Pretest Probability and the Alvarado Score will be high . Experienced clinicians will often perform as well as Clinical Decision Rules .

Stratification is not precise. Determining a Pretest Probability is dependent upon many variables. Deciphering it all into a nice number like “33%” or “50%” or “66%” is difficult. Often we default to a general gestalt. This underscores that fact that our job is as much art as it is science .



Moral of the Morsel

The diagnosis of appendicitis is a difficult one.

The WBC count still is the Last Bastion of the Intellectually Destitute!

Clinical Decision Rules can help when incorporated into a Clinical Pathway that help to standardize care across a regional population.

Nothing is better than your clinical experience and acumen.

References