MODIFIED ALVARADO SCORE IN CHILDREN WITH DIAGNOSIS OF APPENDICITIS

ABSTRACT Background: Appendicitis is one of the most common abdominal emergency. Some predictive scoring systems are recommended to decrease the rate of negative appendectomy. Aim: To evaluate sensitivity, specificity, positive predictive value, and negative predictive value of modified Alvarado score in children who underwent appendectomy. Methods: Four hundred children with initial diagnosis of appendicitis were randomly selected from patients who underwent appendectomy. Modified Alvarado score was used for evaluation of the appendicitis, that was confirmed using histology. Results: Of modified Alvarado score components, anorexia; nausea and vomiting and rebound tenderness were significantly more common in children with positive appendectomy in contrast to patients with negative appendectomy. Sensitivity, specificity, positive predictive value, and negative predictive value for modified Alvarado score were: 91.3%; 38.4%; 87.7%; and 51.2% respectively. Conclusion: Alvarado score has high sensitivity but low specificity for diagnosis of acute appendicitis in children.


INTRODUCTION
A ppendicitis is one of the important surgical emergency among children. Both pediatrician and surgeons should be aware the possibility of appendicitis in children with appendicitis. Despite its high incidence, diagnosis is difficult due to non specific symptoms and atypical presentations 3 .
Variety of different approaches are recommended to decrease negative appendectomies such as predictive scoring system 2 , computer aided diagnosis, inflammatory marker 10 , ultrasonography 8 , and computed tomography.
Alvarado described a clinical scoring system on the basis of eight predictive clinical factors to improve the accuracy of physicians' clinical assessments in diagnosing acute appendicitis. This scoring system produces a maximum total score of 10 points and includes clinical symptoms (nausea and anorexia), signs( fever, shifting pain, right lower quadrant pain, and rebound tenderness) and laboratory findings( leukocytosis and neutrophilia). Right lower quadrant pain and leukocytosis contribute 2 points while the rest contributes 1 point 2 . Kalan et al. omitted shift to left parameter because is not routinely available in many laboratories, and produced a modified score 4 . The modified Alvarado score (MAS) has been widely accepted after it was successfully tested in different studies 1 .
The aim of this study was to evaluate sensitivity, specificity, positive predictive value, and negative predictive value of modified Alvarado score in children who underwent appendectomy.

METHODS
This study was approved by research affairs of Ahvaz Jundishapur University of Medical Sciences. This cross sectional study was carried out in Imam Khomeini Hospital, Ahvaz-Iran. It included 400 children with diagnosis of appendicitis during 2006-2012. Of children who underwent appendectomy 400 children were randomly selected. Appendicitis was confirmed according to pathology report. Modified Alvarado score was used to evaluate appendicitis 4 . Modified Alvarado score is based on three symptoms, three signs, and one laboratory investigation and ranged from 1-9 (Table 1) Appendicitis was confirmed using histopathology evaluation.

RESULTS
In this study, 400 children aged <12 years with primary diagnosis of appendicitis were included. Of these cases, 337(84.3%) had confirmed appendicitis. Of all cases, 63(15.8%) had negative appendectomy. As seen in Table 2, anorexia, nausea and vomiting, and rebound tenderness were significantly more common in children with appendicitis than children without appendicitis. Migratory right iliac fossa pain was the most sensitive part of MAS (Table 3). Of 48 children with score 1-4, 45 had negative histopathology ( Table 4). As seen in Table 4, all children with score 7-9 had positive histopathology.   PPV of MAS in our study was 87.7% which is significantly higher 36.0% in Khanafer et al. study 6 . NPV was 51.2% in our report which was significantly lower than 83.6% in Khanafer et al. study 6 .
In the current study, all children with MAS ≥7, had appendicitis according to pathology report. In our study, 100% of children scored >7 had positive appendicitis. In the study by Kanumba et al. 5 , among children with MAS ≥7, 97.3% had appendicitis which is slightly lower than our study. This difference may be due to age of the patients.

CONCLUSION
Modified Alvarado score has high sensitivity but low specificity for diagnosis of acute appendicitis in children.