Prognostic Value of Neutrophil:Lymphocyte and Platelet:Lymphocyte Ratios for 28-Day Mortality of Patients with AECOPD

Abstract

Objective: Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is the most common cause of hospitalization and death among COPD patients. Clinicians are seeking simple, inexpensive, and easily obtained biomarkers for prognostic evaluation. The aim of this study was to evaluate the association of the neutrophil:lymphocyte ratio (NLR), platelet:lymphocyte ratio (PLR) and lymphocyte:monocyte ratio (LMR) with 28-day mortality and assess the clinical prognostic utility of the NLR, PLR, and LMR in patients with AECOPD.

Methods: A retrospective study was conducted from January 2017 to April 2020 at Ningbo First Hospital. Clinical characteristics, NLR, PLR, LMR, serum levels of CRP, and other data were collected. Relationships between the NLR/PLR/LMR and CRP were evaluated with Pearson's correlation test. Receiver-operating characteristic curves and area under the curve were used to assess the ability of NLR/PLR/LMR to predict 28-day mortality in patients with AECOPD. Optimal cutoff values were determined by the Youden index. Univariate and multivariate logistic regression analysis were used to identify risk factors for 28-day mortality in patients with AECOPD.

Results: By reviewing the medical case records, we collected 533 cases diagnosed with AECOPD for analysis. Death had occurred in 48 (9%) patients within 28 days. Univariate analysis identified age, smoking history, FEV₁% predicted, neutrophil count, lymphocyte count, NLR, PLR, CRP and blood-urea nitrogen as being associated with increased 28-day mortality. Multivariate analysis demonstrated that elevated NLR and PLR were significantly associated with death at 28 days. Receiver-operating characteristic analysis showed that the NLR had the highest area under the curve (0.801), with optimal cutoff of 6.74, sensitivity of 82.54%, and specificity of 71.38%. At a cutoff of 203.6, the corresponding sensitivity, specificity, and area under the curve of the PLR were 76.86%, 65.27%, and 0.75. The LMR failed to show prognostic significance.

Conclusion: Our results indicated that the NLR and PLR were associated with 28-day mortality in patients with AECOPD. These ratios may serve as prognostic biomarkers for short-term mortality in patients hospitalized with AECOPD.

Keywords: AECOPD; biomarker; neutrophil to lymphocyte ratio; platelet to lymphocyte ratio; prognostic value.