Neutrophil-lymphocyte ratio, monocyte-lymphocyte ratio and platelet-lymphocyte ratio in non-affective psychosis: A meta-analysis and systematic review

Objectives: Neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and monocyte/lymphocyte ratio (MLR) are inexpensive and reproducible biomarkers of inflammation. This is the first meta-analysis exploring the role of NLR, MLR and PLR in non-affective psychosis. Methods: Eight studies have been identified from the main electronic databases. Meta-analyses based on random-effects models have been carried out generating pooled standardised mean differences (SMDs) between non-affective psychotic patients and healthy controls (HCs). Results: Subjects with non-affective psychosis had a significant higher NLR and MLR as compared with HC (respectively SMD = 0.715; P < 0.001; I 2 =57.565% and SMD = 0.417; P = 0.001; I 2 =65.754%), confirmed by heterogeneity-based sensitivity analysis. Subgroup analyses showed no differences in effect size across different study characteristics, including drug treatment status, diagnosis, and setting. Meta-regression showed that age influenced the relationship between non-affective psychosis and MLR. A trend of significance, not confirmed by heterogeneity-based sensitivity analysis, was observed in PLR with patients showing higher PLR than HC. Conclusions: Our meta-analysis supports the hypothesis that an inflammatory activation occurs in non-affective psychosis and inflammatory ratios, especially NLR and MLR, may be useful to detect this activation.