Neutrophil-to-Lymphocyte Ratio and Outcomes in Louisiana Covid-19 Patients

Shock. 2020 Jun 19;10.1097/SHK.0000000000001585. doi: 10.1097/SHK.0000000000001585. Online ahead of print.

Abstract

Background: Due to the rapidly escalating number of cases and the low baseline of overall health in Louisiana, we sought to determine the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) in hospitalized COVID patients in 2 major metropolitan areas with the highest prevalence of cases and exceedingly high rates of obesity and other comorbid conditions. We hypothesized that elevated NLR would be a prognostic indicator of mortality.

Methods: This was a review of a prospective registry of adult (18+ years) hospitalized SARS-CoV-2 patients from to two large urban safety net hospitals in Louisiana. Blood cell counts at days 2 and 5 were used to obtain NLR. Receiver operating characteristic (ROC) curve analysis assessed predictive capacity of NLR on mortality. Kaplan-Meier (KM) survival analysis and Cox regression models examined the effect of NLR on survival.

Results: The study population of 125 patients was majority African American (88.6%) and female (54.8%) with a mean age and BMI of 58.7 years and 34.2. Most (96.0%) had comorbidities of which hypertension (72.0%), obesity (66.7%), and diabetes (40.0%) were the most common. Mortality was 18.4%. NLR > 4.94 on day 1 predicted intubation (P = 0.02). NLR above established cutoff values on hospital days 2 and 5 each significantly predicted mortality (P < 0.001 and P = 0.002, respectively).

Conclusions: NLR is a prognostic factor for endotracheal intubation upon hospital admission and independent predictor for risk of mortality in SARS-CoV-2 patients on subsequent hospital days. Clinical research efforts should examine effects of strategies such as arginase inhibition alone and/or inhaled nitric oxide to ameliorate the effects of elevated NLR.