The NHANES Lymphocyte-Neutrophil Report predicts all-cause and cardiovascular mortality in COPD-affected adults in the United States: NHANES results 1999-2018

The neutrophil/lymphocyte ratio (NLR) is considered a biomarker of systemic inflammation and immune activation. However, its relationship to mortality risk in patients with chronic obstructive pulmonary disease (COPD) is unclear.

Data were collected through the National Health and Nutrition Examination Survey (NHANES) between January 1999 and December 2018. The method for calculating NLR is to divide the number of neutrophils by the number of lymphocytes in the total number of blood cells. The optimal NLR threshold for survival results was determined using the statistical method of Maximum Selected Ranks (MSRSM). The relationship between NLR and risk of all-cause mortality and cardiovascular mortality in COPD was investigated using a multivariate Cox regression model. In addition, the restricted cubic spline (RCS) was used to discuss the potential relationship between NLR patients in different groups and mortality risk.

In this study, 716 adults with COPD were included using the statistical method of the maximum selected ranks, of which 208 had a higher NLR ( 2.56) and 508 a lower NLR (<2.56). Over a median follow-up of 111.5 months, 162 patients with COPD died from all causes and 49 patients died from cardiovascular disease. After adjustment for demographic, socio-economic and lifestyle factors, the risk of all-cause mortality (HR = 2.07, 95%CI: 1.46-2.94) and cardiovascular mortality (HR = 3.03, 95%CI: 1.63-5.65) in patients with high NLR was 2- or 3-fold higher than those with lower NLR.

The Kaplan-Meier analysis revealed significantly lower survival rates in patients with higher NLR for all-cause mortality and cardiovascular mortality (p < 0.05).

The restricted cubic spline analysis showed a linear correlation between NLR and risk of all-cause mortality and cardiovascular mortality.

Conclusion: NLR has a high value for independently predicting long-term mortality risks, all causes and cardiovascular, in patients with COPD. Therefore, the NLR can be used as a cost-effective and widely available indicator to assess the prognosis of patients with COPD.