Dynamic Change of Neutrophil to Lymphocyte Ratios and Infection in Patients with Acute Ischemic Stroke

Abstract

Background: Neutrophil to lymphocyte ratio (NLR) on admission was reported to be a predictor of pneumonia after stroke. The aim of this study was to investigate the association between the temporal change of NLR and post-stroke infection and whether infection modified the effect of NLR on the outcome.

Methods: We enrolled patients with acute ischemic stroke within 24 h after onset. The blood was collected on admission, day 1, 3, 7 after admission to detect white blood cells (WBC), neutrophils, and lymphocytes. Primary outcomes included pneumonia, urinary tract infection (UTI), other infection, and the secondary outcome was 3-month death.

Results: Of 798 stroke patients, 299 (37.66%) developed infection with 240 (30.23%) pneumonia, 78 (9.82%) UTI, and 9 (1.13%) other infection. The median time of infection occurrence was 48 h (interquartile range 27-74 h) after onset. NLR reached to the peak at 36 h. For all outcomes, NLR at 36 h after stroke had the highest predictive value than WBC, neutrophil, lymphocyte. NLR was independently associated with the presence of any infection (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.05-1.17), pneumonia (OR 1.12, 95%CI 1.05-1.19), but not UTI (OR 0.95, 95%CI 0.89-1.01). Adding infection or the interaction term did not substantially change the OR of NLR predicting 3-month death (OR 1.09, 95%CI 1.01, 1.17).

Conclusion: Increased NLR around 36 h after stroke was a predictor of infection in patients with acute ischemic stroke. The increased NLR value was associated with a higher risk of 3-month death, which was independent of poststroke infection.

Keywords: Neutrophil to lymphocyte ratios; biomarkers; infection; pneumonia; prognosis; stroke.