Prognostic value of red cell distribution width in patients undergoing percutaneous coronary intervention: a systematic review and meta-analysis.

BACKGROUND: Published studies have reported inconsistent findings regarding the association between preprocedural red cell distribution width (RDW) and adverse outcomes after percutaneous coronary intervention (PCI), and earlier reviews no longer reflect the currently available evidence. This updated systematic review and meta-analysis was conducted to reassess the association between preprocedural RDW and adverse outcomes in patients with coronary artery disease (CAD) undergoing PCI. METHODS: PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception to November 22, 2025. Standard major adverse cardiovascular events (MACE), all-cause mortality (ACM), and cardiovascular mortality (CVM) were prespecified as the primary outcomes, whereas PCI-specific stent-related outcomes were analyzed separately as exploratory outcomes. Hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were extracted for quantitative synthesis when appropriate. RESULTS: Twenty-four studies comprising 31 comparison groups and approximately 83,000 patients were included in the meta-analysis. Elevated preprocedural RDW was associated with higher risks of ACM (HR 1.46, 95% CI 1.31-1.63) and CVM (HR 1.66, 95% CI 1.33-2.07), with the most consistent association observed for ACM. The HR-based analysis of standard MACE showed a statistically significant association (HR 1.24, 95% CI 1.06-1.45; p = 0.007), but the finding was unstable in sensitivity analysis and should therefore be interpreted cautiously. After endpoint reclassification, only one study remained eligible for the OR-based analysis of standard MACE, precluding quantitative synthesis. In-stent restenosis (ISR) was analyzed separately as an exploratory stent-related outcome when eligible studies were available. CONCLUSIONS: Elevated preprocedural RDW was associated with adverse outcomes after PCI. The most consistent association was observed for ACM, whereas the evidence for CVM and standard MACE was less certain. PCI-specific stent-related outcomes should be interpreted as exploratory. Further prospective multicenter studies with standardized endpoint definitions and harmonized RDW cutoff values are warranted. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251249457, PROSPERO, CRD420251249457.