Background: The diagnosis of acute appendicitis must be performed quickly and accurately to reduce the risk of negative appendectomy without increasing the risk of perforation. Objective: To analyze whether Neutrophil-Lymphocyte Ratio (NL-R) in the modified Alvarado score is more accurate in diagnosing acute appendicitis in comparison with total leukocyte and neutrophil. Method: This was a cross-sectional study and the data were collected from Telogorejo Hospital Semarang (Indonesia) from November 2018 until October 2019. The best cut-off point of NL-R for predicting acute appendicitis was provided through receiver operating characteristic (ROC) curve. NL-R was used to replace total leukocyte and neutrophil to form a modified Alvarado score. Area Under Curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the original Alvarado Score and modified Alvarado score were measured. Results: Sensitivity, specificity, positive predictive value, negative predictive value of the original Alvarado score are 100%, 84.6%, 91.3%, and 100% respectively with cut-off point total score of >4.5. Sensitivity, specificity, positive predictive value, negative predictive value of modified Alvarado score were 100%, 100%, 100%, and 100% respectively with cut-off point total score of >5.5. AUC modified Alvarado Score was 1.000 and AUC original Alvarado Score was 0.985. Conclusion: Modified Alvarado score diagnoses acute appendicitis more accurately than the original Alvarado Score.

Keywords : Acute Appendicitis, Leukocyte, Neutrophil, NLR, Original Alvarado Score, Modified Alvarado Score.