The Relationship of Low-Density-Lipoprotein to Lymphocyte Ratio with Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) has been a concern all over the world because of its high prevalence and mortality. The ratio of low-density-lipoprotein to lymphocyte (LLR) has been widely used to predict the prognosis of cerebral infarction, but its association with COPD is less known. We aim to explore the relationship between LLR and COPD and to investigate its indicative role in the severity and prognosis of COPD.

In this study, 279 participants (n = 138 with COPD and n = 138 age- and sex-matched health control) were recruited. COPD patients were divided into two groups according to the optimal cut-off value of LLR determined by the receiver operating characteristic curve (ROC). We collected the clinical characteristics, pulmonary function, LLR, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and other data of all subjects. t-test, Pearson correlation test, logistic regression analysis and other statistical analysis were carried out.

Compared with the healthy control group, COPD patients had a significantly higher LLR level (p < 0.001). The disease was more serious in the high LLR group, which was reflected by Global Initiative for Chronic Obstructive Lung Disease (GOLD) and BMI, airway obstruction, dyspnoea, severe exacerbations (BODE) index and St. George's Respiratory Questionnaire (SGRQ) index (p = 0.001, p = 0.013, p = 0.011, respectively). The forced expiration volume in 1 second (FEV₁) (p = 0.033) and forced expiratory volume in 1 second in percent of the predicted value (FEV₁%) (p = 0.009) in high LLR group were lower. Univariate and multivariate logistic regression analysis showed that LLR was an independent factor affecting the severity of COPD patients (odds ratio [OR] = 2.599, 95% CI: 1.266-5.337, p = 0.009).

We found that LLR is a novel biomarker in predicting the severity of patients with COPD. Further studies with larger database were recommended to verify our findings.