Association between anemic status on admission and clinical outcomes of acute large vessel occlusion

Highlights

• One of 7 patients with acute large vessel occlusion had anemia on admission.

• Anemic status was associated with poorer functional outcomes at 90 days.

• Intracranial hemorrhage was not increased in patients with anemia on admission.

• The 90-day mortality was lower in patients with anemia on admission.

• Effect of anemia was not observed in patients with large ischemic region.

Abstract

Background

Anemia is a frequently observed condition, but its clinical impact on large vessel occlusion (LVO) remains unclear. We examined the association between anemic status on admission and clinical outcomes of LVO in a real-world setting.

Methods

We conducted a post-hoc analysis of the RESCUE-Japan Registry 2, a nationwide registry which enrolled 2408 consecutive patients with LVO who were admitted within 24 h of onset. The patients were classified into anemia (<11 g/dL) and no-anemia (≥11 g/dL) groups according to their hemoglobin level on admission. The primary outcome was defined as a modified Rankin Scale of 0–2 at day 90.

Results

Among the 2373 patients with available baseline hemoglobin data, 307 (13.0%) were classified in the anemia group. Anemia was associated with a lower likelihood of the primary outcome (adjusted odds ratio [OR]: 0.68; 95% confidence interval [CI]: 0.47–0.98) and higher mortality within 90 days (adjusted OR: 1.48; 95% CI: 1.01–2.17). Subgroup analyses showed that the likelihood of achieving the primary outcome between the two groups was different between men and women (P for interaction = 0.049), those with Alberta Stroke Program Early CT Score (ASPECTS) <6 and ASPECTS ≥6 (P for interaction = 0.02), and those with National Institute of Health Stroke Scale (NIHSS) ≥16 and NIHSS < 16 (P for interaction = 0.005).

Conclusions

Anemic state on admission was associated with poorer clinical outcomes of LVO in real-world clinical practice. The effects of anemic status were larger in LVO patients with lower NIHSS or higher ASPECTS.

Introduction

Anemia is a common comorbidity in daily clinical practice, especially among the elderly. The same population also has a higher risk of stroke [1]; thus, the prevalence of anemia in patients with acute stroke has been reported to be 21.9% in a meta-analysis of cohort studies [2] or 24.5% in a large registry data [3]. Previous studies have shown that anemia is associated with poor clinical outcomes in patients with any stroke [3], including ischemic stroke [4].

Recent advancements in thrombolytic therapy or endovascular therapy (EVT) have dramatically improved the disability of patients with acute large vessel occlusion (LVO) [5]. However, the risk stratification of patients or optimal candidates for such treatments is controversial in acute stroke management, even in elderly patients [6]. While anemic status should be considered for treatment selection or risk stratification, the availability of data of patients with anemia was limited in patients with LVO who underwent reperfusion therapy. For example, in a multicenter register-based study analyzing 6866 intravenous thrombolysis-treated patients, anemia was associated with poor functional outcomes and mortality [7]. Additionally, a recent analysis of 712 patients who underwent EVT demonstrated that a lower hemoglobin level at baseline and any hemoglobin decline during stroke treatment were associated with poor outcomes, probably due to enlarging and accelerating infarct growth as observed in magnetic resonance imaging (MRI) [8]. However, no large-scale studies have evaluated the associations between anemic status and clinical outcomes in all consecutive LVO patients with and without reperfusion therapy.

Therefore, we investigated the association between anemic status on admission and clinical outcomes in patients with LVO onset using a nationwide registry that enrolled consecutive patients in daily clinical practice.