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

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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 two 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 Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) patients from two large urban safety net hospitals in Louisiana. Blood cell counts at days 2 and 5 were used to obtain NLR. Receiver operating characteristic curve analysis assessed predictive capacity of NLR on mortality. Kaplan-Meier 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 body mass index 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.

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