Alvarado score in predicting acute appendicitis among patients presenting to a  secondary care unit in Sri Lanka: a new cut-off value

Introduction
The commonest abdominal emergency in high and low-income countries is acute appendicitis. The lifetime risk is about 7%. The young age group is more susceptible, but none of the age groups is immune. As symptoms of acute appendicitis overlap with a few other conditions, accurate diagnosis is difficult. The objectives were to evaluate the sensitivity and specificity of the Alvarado score in the diagnosis of acute appendicitis among patients presenting with abdominal pain suggestive of acute appendicitis among Sri Lankan patients.

Materials and Methods
This was a validation study to determine the use of the Alvarado score for predicting the diagnosis of acute appendicitis at a General Hospital in the Central Province of Sri Lanka. All patients who were admitted to surgical units of General Hospital Matale with suspected acute appendicitis and undergoing appendicectomy were the study population.

Results
A total of 178 patients were recruited for the study of which 83 were histologically confirmed cases and while 89 were not confirmed. The recommended Alvarado score cutoff of 7 returns a sensitivity of 62.5% and a specificity of 91%. On the other hand, a cut-off value of 4.5 provides a sensitivity of 89.2% and a specificity of 86.5%.  This cutoff value increased the Negative Predictive Value to 89.5% from 72% whereas the Positive Predictive Value did not change.

Conclusions
An Alvarado Score cut off value of 4.5 provides a sensitivity of 89.2% and a specificity of 86.5% compared to 62% and 91% respectively at the recommended cutoff value of 7. Since calculating decimals is not practical with the score we suggest lowering the cutoff of the Alvarado score to 5 for patients in Sri Lanka.