Uniformed Services University of the Health Sciences, San Antonio, TX (Drs. Stull and Hale); Uniformed Services University of the Health Sciences, Bethesda, MD (Dr. Servey) jessica.servey@usuhs.edu
The authors reported no potential conflict of interest relevant to this article.
The views expressed here are those of the authors and do not reflect the official views or policy of the Department of Defense or the US government.
The Alvarado score is the oldest scoring rule, developed in 1986; it entails 8 clinical and laboratory variables.6 Ebell et al altered the proposed cutoff values of the Alvarado score to be low risk (< 4), intermediate risk (4-8), and high risk (≥ 9), effectively improving the sensitivity and specificity rates.7
Screening tools cannot confirm appendicitis. Their usefulness is in helping to rule out appendicitis and in deciding for or against imaging.
In a meta-analysis of the Alvarado score that included 42 studies of men, women, and children, the sensitivity for “ruling out” appendicitis with a cutoff of 5 points was 96% for men, 99% for women, and 99% for children.8 The accuracy of a high-risk score (> 7) for “ruling in” appendicitis was less with an overall specificity of 82%.8 The Alvarado score did seem to overestimate appendicitis in women in all score categories.8
The Pediatric Appendicitis Score (PAS) is similar to Alvarado and was prospectively validated in 1170 children in 2002 for more specific guidance in this age group.9 The PAS had excellent specificity in the study; those with a score of ≥ 6 had a high probability of appendicitis. In a study comparing Alvarado with PAS in 311 patients, insignificant differences were noted at a score of ≥ 7 for both tests (sensitivity 86% vs 89%, and specificity 59% vs 50%, respectively).11No scoring system has been found to be sufficiently accurate for use in children 4 years of age and younger.12
The Appendicitis Inflammatory Response (AIR) Score was prospectively validated in 545 patients representing all age groups.10 Subsequently, in a larger prospective multicenter study of 3878 patients older than 5 years, the original cut points were altered, thereby improving test sensitivity and negative predictive value to 99% for those with low probability (0 to 3), and test specificity to 98% for those with high-probability (9 to 12).13 Compared with the Alvarado Score, the AIR Score has higher specificity for those in the high-probability range, and similar exclusion rates in the low-probability range.14
Caveats with clinical decision scores.These tools are accepted and often used. However, challenges that affect generalizability of study data include differences in patient selection for each study (undifferentiated abdominal pain vs appendicitis), prospective vs retrospective designs, and age and gender variations in the patient populations. Despite the numerous scoring systems developed, none can accurately be used to rule in appendicitis. They are best used to assist in ruling out appendicitis and to aid in deciding for or against imaging.
