Neutrophil-to-Lymphocyte Ratio, Platelet-to-Lymphocyte Ratio, and Monocyte-to-Lymphocyte Ratio in Depression: An Updated Systematic Review and Meta-Analysis

Abstract

BackgroundResearch on neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) in depression is still emerging and has increased 3-fold since the first meta-analysis. An updated meta-analysis with sufficient studies can provide more evidence for a potential relationship between NLR, PLR, MLR, and depression.MethodsWe identified 18 studies from the PubMed, EMBASE, Cochrane library, and Web of Science databases. Meta-analyses were performed to generate pooled standardized mean differences (SMDs) and 95% confidence intervals (CIs) between patients with depression and controls. Sensitivity analysis, subgroup analysis, meta-regression, and publication bias were conducted.ResultsA total of 18 studies including 2,264 depressed patients and 2,415 controls were included. Depressed patients had significantly higher NLR and PLR compared with controls (SMD = 0.33, 95% CI: 0.15–0.52, p < 0.001 and SMD = 0.24, 95% CI: 0.02–0.46, p < 0.05, respectively). MLR was slightly higher in depressed individuals compared to controls (SMD = 0.15, 95% CI: −0.26 to 0.55, p > 0.05), despite the absence of significance. Sensitivity analysis removing one study responsible for heterogeneity showed a higher and significant effect (SMD = 0.32, 95% CI: 0.20–0.44) of MLR. Three subgroup analyses of NLR, PLR, MLR, and depression revealed obvious differences in the inflammatory ratios between depressed patients and controls in China and the matched age and gender subgroup. Individuals with post-stroke depression (PSD) had higher NLR and MLR values as compared to non-PSD patients (SMD = 0.51, 95% CI: 0.36–0.67, p < 0.001 and SMD = 0.46, 95% CI: 0.12–0.79, p < 0.01, respectively). Meta-regression analyses showed that male proportion in the case group influenced the heterogeneity among studies that measured NLR values (p < 0.05).ConclusionsHigher inflammatory ratios, especially NLR, were significantly associated with an increased risk of depression. In the subgroup of China and matched age and gender, NLR, PLR, and MLR were all elevated in depressed patients vs. controls. Individuals with PSD had higher NLR and MLR values as compared to non-PSD patients. Gender differences may have an effect on NLR values in patients with depression.

Elevated levels of monocyte-lymphocyte ratio and platelet-lymphocyte ratio in adolescents with non-suicidal self-injury

“…Previous studies have found low-grade systemic inflammation in adult psychiatric inpatients, especially for those diagnosed with schizophrenia and bipolar disorder (BD) [ 11 ]. According to an updated systematic review and meta-analysis of major depressive disorder (MDD) on patient groups in China, the NLR, PLR, and MLR were all elevated in patients with depression, as compared with healthy controls [ 21 ]. These markers are also involved in the inflammatory pathophysiology among children and adolescents with psychiatric disorders.…”

Monocyte-to-lymphocyte ratio is significantly associated with positive QuantiFERON-TB Gold-In-Tube and adult survival: an observational study

“…Presently, more and more researchers have paid more attention to the MLR as a biomarker. For example, Cheng et al found that MLR was significantly associated with an increased risk of depression 19 . Huang et al found that MLR was associated with a 2-year relapse in patients with multiple sclerosis 20 .…”

Clinical and imagenologic significance of the neutrophil-to-lymphocyte ratio in neuromyelitis optica spectrum disorder: A systematic review with meta-analysis

“…Therefore, this elevated neutrophil and low lymphocyte participation can be expressed in the neutrophil-lymphocyte ratio (NLR), which, according to recent studies, could be a novel and clinically relevant biomarker used to indicate a higher risk of depression and to predict poor 3-month functional outcomes in ischemic stroke patients [ 9 , 10 ].…”