Association of Platelet-to-lymphocyte Ratio with Depression Risk: A Systematic Review and Meta-analysis

Ming Zhu¹Wu Li^2*

• ¹Jining Medical University, Jining, China
• ²Shandong Daizhuang Hospital, Jining, China

BACKGROUND: The association of platelet-to-lymphocyte ratio (PLR), a simple marker of inflammation, with depressive disorders has aroused widespread attention, which, however, has not been proved by systematic evidence. Therefore, this study intends to systematically assess the association of PLR with the incidence of depres-sive disorders. METHODS: Embase, Cochrane, PubMed, and Web of Science were searched up to April 2025 for studies investigating the association of PLR with the incidence of de-pressive disorders. The odds ratio (OR) or standardized mean difference (SMD) with 95% confidence interval (CI) was calculated using random-effects models. We as-sessed the robustness of the results and potential sources of heterogeneity by sensitivi-ty and subgroup analyses, respectively, and evaluated publication bias by funnel plots and Egger's test. RevMan 5.4 and Stata 18.0 were utilized for analyses. RESULTS: Twenty-four comparative groups of 25,873 participants were included. PLR as a categorical variable was closely associated with an elevated incidence of de-pressive disorders (OR 1.04, 95% CI 1.00-1.08, P=0.04), and PLR as a continuous variable was significantly higher in the depression group than in the control group (SMD 1.24, 95% CI 0.83-1.66, P<0.00001). Subgroup analyses showed a significant association of PLR with the incidence of depressive disorders in ischemic stroke and tumor patients, but this association did not reach statistical significance in children and adolescents. CONCLUSION: Elevated PLR is positively associated with the incidence of depres-sive disorders, suggesting that PLR may serve as a peripheral inflammatory indicator with potential relevance for the early identification and assessment of depressive dis-orders. This meta-analysis indicates that elevated PLR may be associated with depres-sive disorders, but substantial heterogeneity (I² = 99%) and potential publication bias warrant cautious interpretation. More large-scale prospective cohort studies across races and regions are required in the future to validate the association between PLR and the incidence of depressive disorders. Systematic review registration: PROSPERO (CRD420251052927)