The association of neutrophil–lymphocyte ratio and platelet–lymphocyte ratio with retinal vein occlusion: a systematic review and meta-analysis

The neutrophil–lymphocyte ratio (NLR) and platelet–lymphocyte ratio (PLR) are emerging haematological inflammatory biomarkers. However, their significance in retinal vein occlusion (RVO) and its subtypes, branch and central RVO (BRVO and CRVO, respectively), is uncertain. This systematic review and meta-analysis aimed to clarify the association of NLR and PLR with RVO. We searched MEDLINE (Ovid), EMBASE (Ovid) and the Cochrane Library for studies investigating the association of NLR and PLR with RVO from inception to 2 December 2020. We used random-effects inverse-variance modelling to generate pooled effect measures. We used bivariate Bayesian modelling to meta-analyse the ability of NLR and PLR to differ between individuals with and without RVO and performed meta-regression and sensitivity analyses to explore inter-study heterogeneity. Eight studies published encompassing 1059 patients were included for analysis. Both NLR and PLR were significantly elevated in RVO, with pooled mean differences of 0.63 (95% confidence interval (CI) 0.31–0.95) and 21.49 (95% CI 10.03–32.95), respectively. The pooled sensitivity, specificity and area under the Bayesian summary receiver operating characteristic curve were, respectively, 0.629 (95% credible interval (CrI) 0.284–0.872), 0.731 (95% CrI 0.373–0.934) and 0.688 (95% CrI 0.358–0.872) for NLR; and 0.645 (95% CrI 0.456–0.779), 0.616 (95% CrI 0.428–0.761) and 0.621 (95% CrI 0.452–0.741) for PLR. Mean and variability of age and diabetes mellitus prevalence partially explained between-study heterogeneity. NLR and PLR are significantly elevated in RVO. Future research is needed to investigate the potential prognostic value and independence of these findings.