The Relationship Between Neutrophil-to-Lymphocyte Ratio and the Prevalence and Clinical Outcomes of Depressive Disorders: A Systematic Review and Meta-Analysis.

PURPOSE: The pathophysiology of depressive disorder (DD) has been linked to the inflammatory process, and neutrophil-to-lymphocyte ratio (NLR) is considered a marker of systemic inflammation. Increasing research suggests a potential correlation between NLR and DD onset and prognosis. Current literature, however, presents conflicting results, highlighting a need for further investigation.

METHODS

A systematic literature search was performed in PubMed, Embase, Web of Science, and the Cochrane Library, from inception to September 4, 2024, to identify studies evaluating the relationship between NLR and DD. The primary outcomes pointed to DD prevalence and suicide risk in individuals with DD. Sensitivity and subgroup analyses were conducted to explore the heterogeneity and robustness of results. Meta-analyses were executed using STATA 15.0 and Review Manager 5.4.1.

RESULTS

A total of 37 studies comprising 88,019 participants were included. Categorical analyses showed that high NLR was significantly associated with presence of DD (odds ratio [OR]: 1.57, 95% confidence interval [CI]: 1.28, 1.93). Continuous analyses revealed elevated NLR levels in individuals diagnosed with DD (standardized mean difference [SMD]: 0.73, 95% CI: 0.51, 0.94). Furthermore, increased NLR was associated with heightened suicide risk among those with DD (categorical outcome OR: 1.56, 95% CI: 1.26, 1.94; continuous outcome SMD: 0.42, 95% CI: 0.23, 0.61).

CONCLUSION

Elevated NLR is associated with higher prevalence of DD and increased suicide risk in this patient population. NLR may serve as a promising biomarker for diagnosing and assessing individuals with DD.