Validation of Clinical Prediction Scores for Pediatric Appendicitis: Update with New Cutoff Values for the AIR Score

Gudjonsdottir et al validated four clinical prediction scores for appendicitis in children.[1] The Appendicitis Inflammatory Response (AIR) score and Pediatric Appendicitis Risk Calculator (pARC) had the best performance. A recent validation of the AIR score (AIR2) recommended an adjustment of the low-risk interval to 0 to 3 points compared with 0 to 4 in the design study.[2] This new interval does not change the final conclusion in the study by Gudjonsdottir et al but gives a different result ([Table 1]) worth a comment.

Table 1 Distribution of patients according to the risk level of respective score, with revised intervals for the AIR2 score

	PAS	AIR2	Alvarado	pARC	p-Value
Total cohort	318	318	318	200
No appendicitis	167	167	167	92
Appendicitis	151	151	151	108
Complicated appendicitis	67	67	67	44
Low risk	93 (29)	102 (32)	61 (19)	41 (21)	< 0.001
No appendicitis	86 (51)	91 (54)	56 (33.5)	38 (41)	< 0.001
Appendicitis	7 (5)	11 (7)	5 (3)	3 (3)	0.33
Complicated appendicitis	1 (1)	2 (3)	2 (3)	1 (2)	1
Intermediate risk		171 (53)	80 (25)	115 (57)	< 0.001
No appendicitis		73 (44)	61 (36.5)	53 (58)	< 0.001
Appendicitis		98 (65)	19 (13)	62 (57)	< 0.001
Complicated appendicitis		32 (48)	4 (6)	22 (50)	< 0.001
High risk	225 (71)	45 (14)	177 (56)	44 (22)	< 0.001
No appendicitis	81 (49)	3 (2)	50 (30)	1 (1)	< 0.001
Appendicitis	144 (95)	42 (28)	127 (84)	43 (40)	< 0.001
Complicated appendicitis	66 (99)	33 (49)	61 (91)	21 (48)	< 0.001

Abbreviations: AIR2, revised Appendicitis Inflammatory Response score; PAS, Pediatric Appendicitis Score; pARC, Pediatric Appendicitis Risk Calculator.

Note: Values presented as n (%). p-Values are according to exact test. Scoring intervals: PAS: low = 0–5 and high = 6–10; AIR2 score: low = 0–3 and high = 9–12; Alvarado score low = 0–4 and high = 7–10; pARC: low = 0–14% and high = 85–100%.

With the new risk interval the Pediatric Appendicitis Score (PAS) and AIR2 score assign about half of the no appendicitis patients to the low risk group (51 and 54%, respectively) which is significantly better than the Alvarado and pARC (33.5 and 41%, respectively). All scores have high sensitivity for advanced appendicitis at their low cutoff point (0.97–0.99). Expectant management with planned reexamination, can thus safely be considered for this group.

The revision has no impact for the high-risk group. The AIR2 score and pARC both assign a smaller proportion of patients to this risk group (14 and 22%, respectively) compared with PAS and Alvarado (71 and 56%, respectively) but with much better specificity (0.93 and 0.98 vs. 0.64 and 0.72, respectively). At such a high specificity a diagnostic laparoscopy should be considered before imaging, as a negative imaging study can probably not rule out appendicitis.[3] [4]

Publication History

Received: 23 August 2022

Accepted: 23 August 2022

Accepted Manuscript online:
29 August 2022

Article published online:
14 October 2022

• References

• 1 Gudjonsdottir J, Marklund E, Hagander L, Salö M. Clinical prediction scores for pediatric appendicitis. Eur J Pediatr Surg 2021; 31 (03) 252-260
• 2 Andersson M, Kolodziej B, Andersson RE. Validation of the Appendicitis Inflammatory Response (AIR) Score. World J Surg 2021; 45 (07) 2081-2091
• 3 Jennings R, Guo H, Goldin A, Wright DR. Cost-effectiveness of imaging protocols for suspected appendicitis. Pediatrics 2020; 145 (02) e20191352
• 4 van Randen A, Bipat S, Zwinderman AH, Ubbink DT, Stoker J, Boermeester MA. Acute appendicitis: meta-analysis of diagnostic performance of CT and graded compression US related to prevalence of disease. Radiology 2008; 249 (01) 97-106