Prospective validation of neutrophil-to-lymphocyte ratio as a diagnostic and management adjunct in acute appendicitis

No optimal biomarker exists that accurately diagnoses appendicitis or predicts severity, estimates post-operative complications or total length of hospital stay (LOS).

To prospectively validate the utility of neutrophil-to-lymphocyte (NLR) ratio in predicting the severity of appendicitis, LOS, and 30-day complication rates.

Patients who were admitted with a provisional diagnosis of acute appendicitis over a period of 18 months (Oct 2014-April 2016) were included. Patient demographics and blood results were prospectively collected. Details of imaging, operative intervention, severity of appendicitis, length of stay, and 30-days post admission complications were recorded. Recommended cut-off values of NLR and C-reactive protein for severity of appendicitis were determined using receiver operating characteristic analysis (ROC). These cut-off values were compared with C-reactive protein levels. Mann-Whitney test was performed to assess the correlations between LOS and 30-day complications to NLR.

Four hundred fifty-three patients were included in the study; 55.2% (n = 245) were female with mean patient age of 23 years. Two-thirds (n = 281, 62.03%) underwent operative management. Histologically, appendicitis was confirmed in 214 (76%) patients. A NLR of >6.36 or CRP of >28 were statistically associated with complicated acute appendicitis, with a median of one extra hospital day (p < 0.0001). Mean NLR was statistically higher in patients with post-operative complications (14.42 vs. 7.29 for simple appendicitis group, p < 0.001).

This confirms previous reports that NLR is a simple, readily available adjunct in predicting severity of appendicitis. Additionally, it can aid delineating severe appendicitis that should proceed to surgery without substantial delay.