Neutrophil-to-Lymphocyte Ratio: A Comparative Study of Rupture to Nonruptured Infrarenal Abdominal Aortic Aneurysm

Abstract

Background: Neutrophil-to-lymphocyte ratio (NLR) has recently emerged as a useful predictor of cardiovascular risk and adverse outcomes. According to previous studies, an NLR >5 has the highest sensitivity and specificity for postoperative morbidity and mortality in cardiovascular disease. This study aims to evaluate the NLR in cases of infrarenal unruptured abdominal aortic aneurysm (uAAA) and ruptured abdominal aortic aneurysm (rAAA) and to assess the role of NLR as a prognostic marker of 30-day mortality in patients with uAAA and rAAA who underwent surgical repair.

Methods: This retrospective cohort study examined 255 consecutive patients with intact or ruptured infrarenal AAA who underwent elective or urgent open repair surgery within our clinic in a 10-year period. Differences in prevalence were assessed using chi-squared calculations and values greater than 5 and a P-value less than 0.05 were considered significant. The averages were compared using the ANOVA parameter test when the Bartlett P-value was greater than 0.05.

Results: The average NLR appeared to be significantly higher in the group of patients with rAAA (9.3 vs. 3.39, respectively P < 0001). Furthermore, NLR > 5 occurred in 77.6% of patients with rAAA but only 32.5% in patients with uAAA (odds ratio 5.085; 95% confidence interval [CI]: 3.0025-8.6145; P < 0000.1). In terms of the postoperative prognosis in patients with uAAA, mortality after 30 days postoperatively was considerably higher at 16.6% in patients with NLR >5 compared with 6% for patients with NLR < 5 (RR: 2.77; 95% CI: 1.020-7.55; P < 0.045). In the case of rAAA, mortality after 30 days was higher in patients with NLR >5 (61.44%) than those with NLR < 5 (45.83%). There was no relationship between NLR and length of hospital stay or between NLR and the maximum diameter of the AAA. There was also no difference in the NLR between genders or age groups.

Conclusions: The main findings of this study were the poor outcomes in terms of 30-day mortality for the patients presenting NLR values greater than 5 undergoing open surgical repair in both categories: infrarenal uAAA and rAAA. We also show that NLR is significantly higher among patients with rAAA and that an NLR >5 indicates a 5 times greater possibility of AAA being ruptured. We can use this easily determinable, broadly available, and inexpensive marker to identify high-risk patients, individually, or integrated into a risk-stratification system for patients diagnosed with AAA. This would help in the therapeutic management of AAA, including the avoidance of open surgery when there are prohibitive risks, instead opting for an endovascular approach.