Red cell distribution width as a predictor of cardiovascular events in high-risk patients with statin intolerance: post-hoc analysis of the CLEAR Outcomes trial
Authors: Safarova M , Li N , Lincoff A M , Powell H A , Nissen S E , Nicholls S J , Moriarty P M 
Published: October 2024

Abstract

Background
Despite optimal lipid-lowering therapy there is up to 70% residual risk of recurrent atherosclerotic cardiovascular disease (ASCVD) events, motivating further testing of alternative risk factors and disease pathways. Red cell distribution width (RDW) is a simple and reproducible marker of heterogeneity of cell size in the peripheral blood. High RDW is associated with an increased risk of ASCVD and death, independent of established risk factors. Recent data suggest no significant impact of PCSK9 inhibitors on hsCRP or RDW. In CLEAR Outcomes, baseline hsCRP predicted risk for future cardiovascular (CV) events and death more strongly than elevated LDL-C. It has been shown that bempedoic acid (BA) reduces hsCRP, but its effects on RDW are unknown.

Purpose
To analyze the effect of BA on a 4-component composite of incident myocardial infarction, stroke, coronary revascularization, or cardiovascular death (MACE-4) and for CV death by baseline RDW, and to confirm the association of increased RDW with elevated risk of MACE.

Methods
A total of 13,970 individuals with statin intolerance, with or at high risk for ASCVD, were randomized in the multinational CLEAR Outcomes trial with a median follow up of 3.4 years. Compared to placebo, BA reduced mean LDL-C by 21% and median hsCRP by 22% at 6 months. Quartiles of increasing baseline RDW were assessed as predictors of future adverse events after adjustment for traditional risk factors, hsCRP, and randomized treatment assignment.

Results
Compared to placebo, BA reduced mean RDW by 0.28% at 6 months and 0.13% at 36 months (p&lt;0.0001). There was a weak positive correlation between hsCRP and RDW at baseline (Figure 1). In the placebo group, higher baseline RDW was associated with an increase in the likelihood of MACE-4 and CV death, and the hazard ratios (HR) associated with a 1% increase in RDW after adjusting for covariates and hsCRP were 1.06 (95% CI 1.02-1.11) and 1.22 (1.15-1.29), respectively. When grouped by quartiles of baseline RDW, compared with a reference group with lowest RDW (&lt;13.7%), there was a notable increase in the risk of MACE-4 and CV death among the higher quartiles in the placebo group (Table 1). Those in the 4th quartile demonstrated a 3-fold increase in the risk of CV death (HR, 3.03, 2.00-4.60). The adjusted HRs (95% CI) for BA vs placebo for MACE-4 were generally lower in individuals with elevated baseline RDW than in those in the first quartile [Q1: RDW≤13.7%; 0.96 (0.79-1.17), Q2: RDW 13.7%-14.4%; 0.81 (0.67-0.97), Q3: RDW 14.4%-15.2%; 0.90 (0.75-1.09), and Q4: RDW&gt;15.2%; 0.84 (0.7-1.01)].

Conclusions
In a large randomized controlled clinical trial setting, we confirmed an association between elevated RDW and MACE-4. Compared with placebo, BA demonstrated efficacy in reducing CV risk in patients with moderately increased RDW.Figure 1.Correlation of hsCRP and RDWTable 1.Risk of Outcome by RDW Quartile