Clinical utility of blood neutrophil-lymphocyte ratio in Japanese COPD patients.
BACKGROUND
Neutrophil-to-lymphocyte ratio (NLR) is a biomarker of inflammation in chronic obstructive pulmonary disease (COPD) patients. But, a meaningful threshold and the longitudinal changes are unknown. We aimed to investigate the association between NLR and the clinical characteristics of COPD patients and to determine a meaningful threshold and the longitudinal changes for NLR.


METHODS
Keio University and its affiliate hospitals conducted an observational COPD cohort study over 3 years. We performed a blood examination and a pulmonary function test. Blood examination was completed at baseline and annually thereafter, at a time when the disease was stable. Two hundred seventy-four patients who had at least 3 blood examinations over 3 years were included.


RESULTS
Baseline NLR was correlated with baseline C-reactive protein (CRP) (r = 0.18, p = 0.003) and SAA (r = 0.34, p <  0.001). We defined an NLR score of 2.7 as the arbitrary cut-off value based on upper quartile points. COPD patients with NLR ≥ 2.7 were older (p = 0.037), had a lower BMI (p = 0.005) and a lower %FEV1 (p = 0.0003) compared to patients with NLR < 2.7. Receiver-operating-characteristic (ROC) curves showed the optimal cutoff for the baseline NLR in the predicting moderate/severe exacerbation to be 2.7, which was same as the upper quartile points. Follow-up analysis over 3 years revealed that the differences in the trends of NLR among the three groups based on the categories of exacerbations (moderate or severe, mild, no exacerbation) were significant (p = 0.006).


CONCLUSIONS
NLR is associated with COPD severity and exacerbations. For predicting exacerbations, we estimated the threshold of NLR to be 2.7 at baseline.


TRIAL REGISTRATION
Clinical trial registered with the University Hospital Medication Information Network ( UMIN000003470 , April 10, 2010).
['Sakurai|Kaori|K|', 'Chubachi|Shotaro|S|http://orcid.org/0000-0002-5046-3762', 'Irie|Hidehiro|H|', 'Tsutsumi|Akihiro|A|', 'Kameyama|Naofumi|N|', 'Kamatani|Takashi|T|', 'Koh|Hidefumi|H|', 'Terashima|Takeshi|T|', 'Nakamura|Hidetoshi|H|', 'Asano|Koichiro|K|', 'Betsuyaku|Tomoko|T|']
D000328:Adult D000368:Aged D005260:Female D006801:Humans D007564:Japan D007958:Leukocyte Count D008214:Lymphocytes D008297:Male D008875:Middle Aged D009504:Neutrophils D062072:Patient Acuity D011237:Predictive Value of Tests D029424:Pulmonary Disease, Chronic Obstructive D015203:Reproducibility of Results D012129:Respiratory Function Tests D012720:Severity of Illness Index D000067251:Symptom Flare Up
COPD NLR Acute exacerbation Comorbidity