A U-shaped association between baseline neutrophil count and COVID-19-related mortality: a retrospective cohort study.

Background Several descriptive studies have reported that higher neutrophil count (NC) may be correlated with poor prognosis in patients with confirmed COVID-19 infection. However, the findings from these studies are limited by methodology and data analysis. Methods This study is a cohort study. We non-selectively and consecutively collected a total of 663 participants in a Chinese hospital from January 7 to February 28. Standardized and two-piecewise Cox regression model were employed to evaluated the association between baseline neutrophil count (bNC), NC change rate (NCR), and death. Results bNC had a U-shaped association with death. In the range of 0.1 to ≤1.49×109 /L (HR = 0.19, 95% CI = 0.05 to 0.66) and > 3.55×109 /L of bNC (HR = 2.82, 95% CI = 1.19 to 6.67), the trends on bNC with mortality were opposite. By recursive algorithm, the bNC at which the risk of the death was lower was range of >1.49 to ≤3.55×109 /L (HR=13.64, 95%CI=0.25 to 74.71). In addition, we find NCRs (NCR1 and NCR2) is not associated with COVID-19-related deaths. Conclusions Compared with NCR, bNC has the potential to be used for early risk stratification in patients with COVID-19 infection. The relationship between bNC and mortality was U-shaped. The safe range of bNC was 1.64 to 4.0 ×109 /L. Identifying the correlation may be helpful for early risk stratification and medical decision making. This article is protected by copyright. All rights reserved.