TABLE 1.
Studies investigating the predictive roles of neutrophil to lymphocyte ratio (NLR) in chronic obstructive pulmonary disease (COPD)
| First author [ref.] | Patients enrolled | Study design | Main findings |
| NLR as predictor of exacerbations in stable COPD | |||
| Günay [36] | COPD: 178 stable, 91 exacerbations; 50 healthy controls | Retrospective | NLR significantly different between controls and COPD patients, but not between patients with stable COPD and with exacerbations |
| Furutate [37] | COPD: 141 stable, 49 exacerbations | Retrospective | NLR significantly higher in patients with exacerbations. Significant correlations with FEV1, BODE, BMI, 6MWT, mMRC, low-attenuation area and fat-free mass index |
| Lee [38] | 885 COPD, 233 exacerbations (1 year) | Retrospective | NLR significantly higher in patients with exacerbations. NLR predictor of exacerbations. Significant correlation with FEV1 |
| Taylan [39] | COPD: 100 stable with exacerbation; 80 healthy controls | Retrospective | NLR significantly higher in patients with exacerbations, NLR higher in stable COPD than in controls. NLR ≥3.29 predictor of exacerbation |
| Farah [40] | COPD: 13 stable, 72 exacerbations; 15 healthy controls | Retrospective | NLR significantly higher in patients with exacerbations. NLR ≥7.3 predictor of exacerbation |
| Kurtipek [41] | COPD: 94 male patients, 48 with exacerbations | Prospective | NLR significantly higher in exacerbations. NLR ≥3.3 predictor of exacerbation |
| Bilir [42] | COPD: 467 patients, 186 with exacerbations; 215 healthy controls | Retrospective | NLR significantly higher in COPD and in exacerbations. NLR ≥3.35 predictor of exacerbation |
| In [43] | COPD: 103 patients, 47 with exacerbations; 40 healthy controls | Retrospective | NLR significantly higher in COPD and in exacerbations. NLR ≥3.34 predictor of exacerbation |
| NLR as marker of exacerbation aetiology (infection) | |||
| Tanriverdi [44] | COPD: 77 patients with exacerbations | Prospective | Bacterial infection in 37.4% of the patients. NLR ≥11.5 significantly associated with bacterial infection |
| van de Geijn [45] | COPD: 17 stable and 45 exacerbations (22 bacterial and 23 non-bacterial) | Retrospective | NLR determined with different methods significantly higher in exacerbations than in stable, and in bacterial exacerbations than in non-bacterial ones |
| NLR in COPD patients with comorbidities | |||
| Vaguliene [46] | 139 lung cancer; COPD: 40 stable and 55 with lung cancer; 33 healthy controls | Prospective | NLR significantly higher in lung cancer patients. No significant difference in NLR between COPD and healthy patients |
| Yasar [47] | COPD: 140, 63 with metabolic syndrome; 50 healthy controls | Retrospective | NLR significantly higher in COPD patients than in controls, NLR significantly higher in those with metabolic syndrome. NLR ≥2.56 predictor of COPD |
| Arisou [48] | COPD: 40 stable; 40 healthy controls | Prospective | NLR was higher in COPD patients than in the control group. Significant positive correlation between tricuspid atrial conduction time and NLR |
| NLR as predictor of hospitalisation | |||
| Lee [49] | COPD: 61 stable, 59 exacerbations; 28 healthy controls | Prospective | NLR significantly higher in patients with exacerbations. Significant correlations with mMRC and 6MWT. NLR ≥2.8 predictor of hospitalisation |
| NLR as predictor of re-hospitalisation | |||
| Duman [50] | COPD: 1704 with exacerbations, 351 with >2% eosinophils | Retrospective | NLR significantly lower in the eosinophilic group. NLR predictor of re-admission and death |
| NLR as predictor of death | |||
| Rahimirad [51] | COPD: 315, 70 died in hospital | Retrospective | NLR significantly higher in patients who died in hospital. NLR ≥4 predictor of in-hospital death |
| Yao [52] | COPD: 303 with exacerbations, 33 died in hospital | Retrospective | NLR significantly higher in patients who died in hospital. NLR ≥6.24 predictor of in-hospital death |
| Xiong [53] | COPD: 368 stable, 96 died during follow-up; 298 healthy controls | Prospective | NLR significantly higher in COPD patients than in controls. NLR significantly higher in those who died during follow-up. NLR ≥3.3 predictor of death |
| Kumar [54] | COPD: 181 with exacerbation, 16 died within 90 days | Retrospective | NLR significantly higher in patients who died within 90 days from exacerbation |
| Saltürk [55] | COPD in ICU: 647, 62 with >2% eosinophils | Retrospective | NLR significantly lower in the eosinophilic group. NLR ≥16 predictor of death |
| NLR and oral corticosteroid therapy in COPD | |||
| Sørensen [56] | COPD: 386, 84 using glucocorticoids | Prospective | NLR significantly lower in patients without glucocorticoids, NLR predictor of death in patients not treated with glucocorticoids |
FEV1: forced expiratory volume in 1 s; BMI: body mass index; BODE: BMI, airflow obstruction, dyspnoea, exercise capacity; 6MWT: 6-min walking test; mMRC: modified Medical Research Council dyspnoea scale; ICU: intensive care unit.