Association of Blood Inflammatory Biomarkers with Clinical Outcomes in Patients with AECOPD: An 8-Year Retrospective Study in Beijing

PURPOSE: To discover potential inflammatory biomarkers, which can compare favorably with traditional biomarkers, and their best cut-offs at first admission to predict clinical outcomes (short-term and long-term) and the risk of readmission among acute exacerbations of chronic obstructive pulmonary disease (AECOPD) patients. PATIENTS AND METHODS: Novel inflammatory biomarkers (such as the neutrophil–lymphocyte ratio [NLR], platelet–lymphocyte ratio [PLR], etc.) were compared with traditional biomarkers by Pearson’s correlation test. Logistic regression analysis and receiver operating characteristic (ROC) curves were applied to judge the accuracy of these novel biomarkers to predict in-hospital mortality. RESULTS: Surviving AECOPD patients had lower NLR, PLR, and lymphocyte-to-monocyte ratios than non-survival patients (all P < 0.001). According to Pearson’s correlation test, there was a linear correlation between novel and traditional biomarkers (all P < 0.05). In terms of a single biomarker, the AUC value of NLR was the largest, which was not inferior to C-reactive protein (Z-P = 0.064), and superior to erythrocyte sedimentation rate (Z-P = 0.002) and other novel single inflammatory biomarkers (all Z-P < 0.05). The mortality of patients with NLR ≥ 4.43 was 2.308-fold higher than that of patients with NLR < 4.43. After dividing patients into a higher or lower NLR group, pooled results showed that patients with NLR ≥ 4.43 had a higher rate of treatment failure, intensive care unit admission, longer hospital length of stay, one-year mortality after the index hospitalization, and overall mortality than patients with NLR < 4.43 (all P < 0.001). Patients with NLR ≥ 4.43 were associated with higher and earlier first readmission due to AECOPD than patients with lower NLR. CONCLUSION: NLR was the best to forecast the clinical prognosis and readmission risk among AECOPD patients, which was not inferior to CRP, and the best cut-off value of NLR was 4.43.