Neutrophil to lymphocyte ratio useful to identify risk for COPD, lung function impairment

Neutrophil to lymphocyte ratio may be a clinically relevant biomarker associated with increased risk for COPD and lung function impairment, according to data published in JAMA Network Open.

“Neutrophil to lymphocyte ratio may be a useful, readily attainable and inexpensive tool to identify people with high risks of lung function impairment and chronic obstructive pulmonary disease. We can even increase the prediction by combining both neutrophil to lymphocyte ratio and the methylation of aryl hydrocarbon receptor repressor,” Xu Gao, PhD, with the Laboratory of Environmental Precision Biosciences at the Mailman School of Public Health at Columbia University, New York, told Healio.

Researchers conducted a longitudinal cohort study that included 1,549 white male veterans in the United States (mean age, 68.3 years) with more than 30 years of follow-up available. The researchers’ aim was to assess the association of neutrophil to lymphocyte ratio and lung function, COPD and hypomethylation of ch05575921. Gao and colleagues evaluated 7,466 visits from the 1,549 individuals, as well as a subgroup of 1,411 participants without COPD, September 2019 to January 2020.

Primary exposure was neutrophil to lymphocyte ratio estimated via automated whole blood cell counts on blood samples collected during each visit. The researchers also measured methylation level of cg05575921 via blood DNA in a subgroup of 1,228 visits. Outcomes included lung function measured by FEV₁ in liters, FVC in liters, percentage FVC exhaled, maximal midexpiratory flow rate in liters and COPD status.

Xu Gao

Results showed a 1-unit increase in neutrophil to lymphocyte ratio was associated with a significant mean decrease of 0.021 L in FEV₁, 0.016 L in FVC, 0.29% L in FEV₁/FVC and 3.65 L/min maximal midexpiratory flow rate. The researchers reported that observed changes in neutrophil to lymphocyte ratio up to 10 years were associated with longitudinal changes in lung function in this cohort.

The observed increase in neutrophil to lymphocyte ratio was associated with a 9% higher odds of COPD (OR = 1.09; 95% CI, 1.03-1.15) for all visits and 27% higher risk for incident COPD (OR = 1.07; 95% CI, 1.07-1.51) for veterans without COPD at baseline.

In other results, an increase in neutrophil to lymphocyte ratio of 1 unit was associated with a mean 0.0048 decrease in cg05575921 hypomethylation, which the researchers noted “may mediate the adverse association of [neutrophil to lymphocyte ratio]-related inflammation on lung function.”

“Clinically, blood cell count estimation is a routine test more commonly requested in clinical practice than measuring serum inflammatory biomarkers. Therefore, clinicians may be able to use this information to quickly obtain the patients’ inflammatory status with neutrophil to lymphocyte ratio and thus decide on relevant interventions with medications or rehabilitation,” Gao said. “Multidisciplinary studies based on larger cohorts or clinical trials are required to confidently validate our findings and to explore the potential biological mechanisms.”

For more information:

Xu Gao, PhD, can be reached at xg2307@cumc.columbia.edu; Twitter: @XuGao11, @BaccarelliLab and @BaccarelliAA.