The impact of platelet-to-lymphocyte ratio on clinical outcomes in heart failure: a systematic review and meta-analysis

Background: Inflammation has been suggested to play a role in heart failure (HF) pathogenesis. However, the role of platelet-to-lymphocyte ratio (PLR), as a novel biomarker, to assess HF prognosis needs to be investigated. We sought to evaluate the impact of PLR on HF clinical outcomes. Methods: English-published records in PubMed/Medline, Scopus, and Web-of-science databases were screened until December 2023. Relevant articles evaluated PLR with clinical outcomes (including mortality, rehospitalization, HF worsening, and HF detection) were recruited, with PLR difference analysis based on death/survival status in total and HF with reduced ejection fraction (HFrEF) patients. Results: In total, 21 articles (n = 13,924) were selected. The total mean age was 70.36 +/- 12.88 years (males: 61.72%). Mean PLR was 165.54 [95% confidence interval (CI): 154.69-176.38]. In total, 18 articles (n = 10,084) reported mortality [either follow-up (PLR: 162.55, 95% CI: 149.35-175.75) or in-hospital (PLR: 192.83, 95% CI: 150.06-235.61) death rate] and the mean PLR was 166.68 (95% CI: 154.87-178.50). Further analysis revealed PLR was significantly lower in survived HF patients rather than deceased group (152.34, 95% CI: 134.01-170.68 versus 194.73, 95% CI: 175.60-213.85, standard mean difference: -0.592, 95% CI: -0.857 to -0.326, p < 0.001). A similar trend was observed for HFrEF patients. PLR failed to show any association with mortality risk (hazard ratio: 1.02, 95% CI: 0.99-1.05, p = 0.289). Analysis of other aforementioned outcomes was not possible due to the presence of few studies of interest. Conclusion: PLR should be used with caution for prognosis assessment in HF sufferers and other studies are necessary to explore the exact association.