Evaluation of red blood cell distribution width and neutrophil to lymphocyte ratio in patients with major depressive disorder

Background: Inflammatory cytokines are an important role in mediating depression through communicating peripheral inflammation to the brain. Several inflammatory markers are increased in patients with major depressive disorder (MDD), such as C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Red cell distribution width (RDW) and neutrophil to lymphocyte ratio (NLR) have been considered as inflammatory markers in various diseases. Therefore, it is reasonable to hypothesize the association between RDW, NLR and MDD. Methods: The medical records of 167 MDD patients who were admitted to Affiliated Hospital of Youjiang Medical University for Nationalities between January 2012 and January 2015 were reviewed in this retrospective study. Results: RDW and NLR values were significantly high in patients with MDD compared with healthy controls (13.4±0.87 vs. 12.9±0.58, P<0.001; 1.9±0.73 vs. 1.7±0.62, P=0.025). There were no correlation between RDW, NLR and disease duration in patients with MDD (r=0.045, P=0.279; r=0.055, P=0.188). In multivariable logistic regression after adjustment for values of haemoglobin (Hb), RDW and NLR, RDW and NLR were associated with MDD independently of hemoglobin (Hb) (OR=4.220, 95% CI: 2.555-6.970, P<0.001; OR=1.624, 95% CI: 1.130-2.332, P=0.009). ROC analysis showed that an optimal RDW cutoff of 13.05 (area under the curve 0.780, 95 CI%: 0.729-0.831, P<0.001) was associated with MDD, the sensitivity and specificity of an elevated RDW values in assessing MDD patients were 75.69% and 70.66%, respectively. Conclusions: The present study suggests that RDW and NLR are increased in patients with MDD, elevated RDW and NLR values may support an evidence of inflammation in the etiology of MDD.