TABLE 2.
Studies investigating relationships between neutrophil to lymphocyte ratio (NLR) and other biomarkers in chronic obstructive pulmonary disease (COPD)
| First author [ref.] | Main markers investigated | Main findings |
| Günay [36] | CRP, PDW, RDW, MPV | Increased levels of WBC, CRP, RDW and MPV in COPD. Significant positive correlation of NLR with CRP and RDW, and negative correlation with MPV in COPD |
| Furutate [37] | CRP | CRP significantly increased in COPD. Significant positive correlation between NLR and CRP |
| Taylan [39] | CRP, WBC, RDW, PDW, MPV, ESR | Significant correlations with CRP, WBC and ESR. High NLR values in AECOPD patients with low CRP, WBC or ESR levels |
| Farah [40] | CRP, WBC, RDW, MPV, CD64 | RDW, CRP and CD64 significantly elevated in AECOPD. Significant correlations of NLR with CRP and RDW |
| Kurtipek [41] | CRP, PLR | CRP and PLR are significantly higher in AECOPD. Significant positive correlation with CRP. CRP AUC was better than that of NLR, which was better than AUC for PLR |
| Bilir [42] | CRP | Significant positive correlation with CRP. CRP AUC better than AUC for NLR |
| In [43] | CRP, ESR | Significant positive correlation with CRP and ESR |
| Tanriverdi [44] | CRP, PCT | PCT higher in infections. Significant but weak positive correlation with CRP. AUC value of PCT significantly better in predicting bacterial infection compared with the CRP or the NLR |
| van de Geijn [45] | CRP, PCT and others | CRP and PCT higher in AECOPD, especially bacterial ones. Addition of PCT to CRP increased specificity for bacterial AECOPD compared to CRP alone |
| Yasar [47] | CRP, RDW, MPV, PDW | CRP, RDW and PDW were higher while MPV was lower in COPD. CRP, RDW and PDW were higher and MPV was lower in patients who had metabolic syndrome |
| Lee [49] | CRP | CRP was higher in exacerbations than in healthy controls |
| Duman [50] | CRP, platelet/MPV | CRP was significantly higher in the non-eosinophilic group. The platelet/MPV ratio was not different between the two groups. Survival negatively influenced by elevated CRP in the non-eosinophilic group |
| Rahimirad [51] | dNLR, MLR, PLR | dNLR higher in dead patients than in those discharged alive. MLR and PLR not significant in multivariate analysis |
| Yao [52] | CRP, PLR | NLR levels correlated with serum CRP levels in AECOPD. CRP and PLR levels higher in dead patients than in survivors. CRP AUC higher than that of PLR in predicting death |
| Xiong [53] | ESR, EBR, CRP, RDW | EBR higher in COPD than in controls, and in survivors than in dead patients. EBR and CRP are predictors of mortality, not ESR or RDW |
| Kumar [54] | PLR, urea | PLR significantly associated to 90-days mortality, AUC poor |
| Saltürk [55] | CRP, platelet/MPV | CRP >50 mg·mL−1 risk factor for mortality |
| Sørensen [56] | Calprotectin, YKL-40 | Correlation with calprotectin. In the group not treated with systemic glucocorticoids, plasma calprotectin was significantly associated with mortality. In the group treated with systemic glucocorticoids, higher plasma YKL-40 was significantly associated with mortality |
CRP: C-reactive protein; PDW: platelet distribution width; RDW: red cell distribution width; MPV: mean platelet volume; WBC: white blood cell; ESR: erythrocyte sedimentation rate; PLR: platelet to lymphocyte ratio; PCT: procalcitonin; dNLR: derived neutrophil to lymphocyte ratio; MLR: monocyte to lymphocyte ratio; EBR: eosinophil to basophil ratio; AECOPD: acute exacerbation of COPD; AUC: area under the curve.