Anemia in young patients with ischaemic stroke

Anemia and Optimal Transfusion Thresholds in Brain-Injured Patients: A Narrative Review of the Literature

Anemia is a highly prevalent condition that may compromise oxygen delivery to vital organs, especially among the critically ill. Although current evidence supports the adoption of a restrictive transfusion strategy and threshold among the nonbleeding critically ill patient, it remains unclear whether this practice should apply to the brain-injured patient, given the predisposition to cerebral ischemia in this patient population, in which even nonprofound anemia may exert a detrimental effect on clinical outcomes. The purpose of this review is to provide an overview of the pathophysiological changes related to impaired cerebral oxygenation in the brain-injured patient and to present the available evidence on the effect of anemia and varying transfusion thresholds on the clinical outcomes of patients with acute brain injury.

Association of anemia with mortality in young adult patients with intracerebral hemorrhage

This study aimed to examine the association of hemoglobin concentration with a 90-day mortality of young adult patients with ICH in a large retrospective cohort. A retrospective observational study was conducted between December 2013 and June 2019 in two tertiary academic medical centers in China. We defined patients with hemoglobin concentration < 80 g/L as severe anemia and 80-120/130 g/L as mild to moderate anemia. We also defined patients with hemoglobin concentration > 160 g/L as high hemoglobin. Associations of hemoglobin and outcomes were evaluated in multivariable regression analyses. The primary outcome was mortality at 90 days. We identified 4098 patients with ICH who met the inclusion criteria. After adjusting primary confounding variables, the 90-day mortality rate was significantly higher in young patients with severe anemia (OR, 39.65; 95% CI 15.42-101.97), moderate anemia (OR, 2.49; 95% CI 1.24-5.00), mild anemia (OR, 1.89; 95% CI 1.20-2.98), and high hemoglobin (OR, 2.03; 95% CI 1.26-3.26) group than in young patients of the normal group. The younger age was associated with a higher risk of death from anemia in patients with ICH (P for interaction = 0.01). In young adult patients with ICH, hemoglobin concentration was associated with 90-day mortality, and even mild to moderate anemia correlated with higher mortality. We also found that in ICH patients with anemia, younger age was associated with higher risk.

Impact of anemia on acute ischemic stroke outcomes: A systematic review of the literature

INTRODUCTION

Anemia has been reported in nearly 40% of acute ischemic stroke (AIS) patients and is linked to significant morbidity and disability. The presence of anemia is associated with worse outcomes in AIS, specifically in the presence of large vessel occlusion (LVO). An optimal hemoglobin (Hb) target specific to this pathology has not yet been established. The goal of this review is to systematically review literature that observes the association that exists between AIS outcomes and hemoglobin (Hb) levels.

METHODS

A systematic review was performed in accordance with guidelines for the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) to identify studies from 2008-2022. The following inclusion and exclusion criteria were used: studies of adult patients with AIS; must describe outcomes with regard to Hb levels in AIS (not limited to LVO); must be written in English. The clinical variables extracted included Length of Stay (LOS), modified rankin score (mRS), Hb levels, and mortality.

RESULTS

A total of 1,154 studies were gathered, with 116 undergoing full text review. 31 studies were included in this review. The age of patients ranged from 61.4 to 77.8. The presence of anemia in AIS increased LOS by 1.7 days on average and these patients also have a 15.2% higher rate of mortality at one year, on average.

DISCUSSION

This data suggests that the contemporary thresholds for treating anemia in AIS patients may be inadequate because anemia is strongly associated with poor outcomes (e.g., mRS>2 or mortality) and increased LOS in AIS patients. The current generalized Hb threshold for transfusion (7 g/dL) is also used in AIS patients, however, a more aggressive transfusion parameter should be further explored based on these findings. Further studies are required to confirm these findings and to determine if a more liberal RBCT threshold will result in clinical benefits.

Association between aspirin-induced hemoglobin decline and outcome after acute ischemic stroke in G6PD-deficient patients

Aims

The risk of hemoglobin decline induced by low‐dose aspirin in glucose‐6‐phosphate dehydrogenase (G6PD) deficiency remains unknown, and its influence on stroke outcome remains to be investigated. This study aimed to evaluate the effect of G6PD deficiency on hemoglobin level during aspirin treatment and its association with outcome after acute ischemic stroke.

Methods

In total, 279 patients (40 G6PD‐deficient and 239 G6PD‐normal) with acute ischemic stroke treated with aspirin 100 mg/day from a cohort study were examined. The primary safety endpoint was a hemoglobin decline ≥25 g/L or 25% from baseline within 14 days after aspirin treatment. Poor outcomes were defined as a modified Rankin Scale score ≥2 at 3 months. The χ² test was used to compare stroke outcomes, and multivariate logistic regression analyses were performed to analyze the association between hemoglobin level and outcomes.

Results

The G6PD‐deficient group had lower baseline hemoglobin and tended to develop comorbid pulmonary infection more frequently (p < 0.05). The proportion of patients with hemoglobin decline ≥25 g/L or 25% from baseline (15.0% vs. 3.3%; p = 0.006) and anemia (30.0% vs. 14.6%; p = 0.016) after aspirin treatment was higher in the G6PD‐deficient group, which was accompanied by a more significant bilirubin increase. The rate of poor functional outcomes at 3 months after acute ischemic stroke was higher in the G6PD‐deficient group (Risk ratio = 1.31 [95% confidence interval (CI) = 1.10–1.56]; p = 0.017). Confounder‐adjusted analysis showed that lower hemoglobin levels (odds ratio = 0.98 [95% CI = 0.96–0.99]; adjusted p = 0.009) increased the risk of poor functional outcomes.

Conclusion

Hemoglobin decrease with bilirubin increase after aspirin treatment in patients with G6PD deficiency suggests hemolysis, which may influence stroke prognosis. The risk of hemoglobin decline should be carefully monitored in G6PD‐deficient patients with ischemic stroke taking aspirin.

Safety and efficacy of low-dose aspirin in ischemic stroke patients with different G6PD conditions

BACKGROUND AND PURPOSE

Aspirin is the first recommended antiplatelet agent to prevention secondary stroke, but its safety and efficacy in stroke patients with glucose-6-phosphate dehydrogenase deficiency remain unclear. We sought to evaluate its safety and efficacy in ischemic stroke patients with and without glucose-6-phosphate dehydrogenase deficiency.

METHODS

Patients with ischemic stroke receiving aspirin (100 mg/day) for three months were recruited for a multicenter, prospective, cohort study. Blood glucose-6-phosphate dehydrogenase activity was examined after stroke. Safety outcomes including acute hemolysis, moderate-to-severe bleeding, and death (vascular, all-cause), and efficacy outcome indicated as stroke recurrence were evaluated at three months. Risk factors associated with moderate-to-severe bleeding and all-cause death were determined using multivariate or Cox regression analysis.

RESULTS

Among the included 1121 patients, 81 of 130 glucose-6-phosphate dehydrogenase deficient and 576 of 991 glucose-6-phosphate dehydrogenase normal patients received aspirin for three months. Acute hemolysis was observed in one of the glucose-6-phosphate dehydrogenase deficient and in none of the glucose-6-phosphate dehydrogenase normal patients (p = 0.876). The rates of moderate-to-severe bleeding were 2.5% and 0.3% (p = 0.045), and the percentages of all-cause death were 6.2% and 1.4% (p = 0.008) in the glucose-6-phosphate dehydrogenase deficient and glucose-6-phosphate dehydrogenase normal patients. Stroke recurrence rate was similar in the two groups (2.5% vs. 1.7%; p = 0.608). Glucose-6-phosphate dehydrogenase deficiency was significantly associated with increased risk of moderate-to-severe bleeding (adjust p = 0.048) and all-cause death during aspirin use (adjust p = 0.008).

CONCLUSIONS

Long-term low-dose aspirin therapy might relate to worse safety outcomes in patients with glucose-6-phosphate dehydrogenase deficiency and large clinical trials are needed to further confirm these findings.

Effect of haemoglobin levels on outcome in intravenous thrombolysis-treated stroke patients

INTRODUCTION

Alterations in haemoglobin levels are frequent in stroke patients. The prognostic meaning of anaemia and polyglobulia on outcomes in patients treated with intravenous thrombolysis is ambiguous.

PATIENTS AND METHODS

In this prospective multicentre, intravenous thrombolysis register-based study, we compared haemoglobin levels on hospital admission with three-month poor outcome (modified Rankin Scale 3-6), mortality and symptomatic intracranial haemorrhage (European Cooperative Acute Stroke Study II-criteria (ECASS-II-criteria)). Haemoglobin level was used as continuous and categorical variable distinguishing anaemia (female: <12 g/dl; male: <13 g/dl) and polyglobulia (female: >15.5 g/dl; male: >17 g/dl). Anaemia was subdivided into mild and moderate/severe (female/male: <11 g/dl). Normal haemoglobin level (female: 12.0-15.5 g/dl, male: 13.0-17.0 g/dl) served as reference group. Unadjusted and adjusted odds ratios with 95% confidence intervals were calculated with logistic regression models.

RESULTS

Among 6866 intravenous thrombolysis-treated stroke patients, 5448 (79.3%) had normal haemoglobin level, 1232 (17.9%) anaemia - of those 903 (13.2%) had mild and 329 (4.8%) moderate/severe anaemia - and 186 (2.7%) polyglobulia. Anaemia was associated with poor outcome (ORadjusted 1.25 (1.05-1.48)) and mortality (ORadjusted 1.58 (1.27-1.95)). In anaemia subgroups, both mild and moderate/severe anaemia independently predicted poor outcome (ORadjusted 1.29 (1.07-1.55) and 1.48 (1.09-2.02)) and mortality (ORadjusted 1.45 (1.15-1.84) and ORadjusted 2.00 (1.46-2.75)). Each haemoglobin level decrease by 1 g/dl independently increased the risk of poor outcome (ORadjusted 1.07 (1.02-1.11)) and mortality (ORadjusted 1.08 (1.02-1.15)). Anaemia was not associated with occurrence of symptomatic intracranial haemorrhage. Polyglobulia did not change any outcome.

DISCUSSION

The more severe the anaemia, the higher the probability of poor outcome and death. Severe anaemia might be a target for interventions in hyperacute stroke.

CONCLUSION

Anaemia on admission, but not polyglobulia, is a strong and independent predictor of poor outcome and mortality in intravenous thrombolysis-treated stroke patients.

Influence of Hemoglobin Concentration on Stroke Recurrence and Composite Vascular Events

Background and Purpose- We evaluated whether hemoglobin concentration at admission was associated with stroke recurrence and composite vascular events (stroke, myocardial infarction, and vascular death) in acute ischemic stroke. Methods- We collected data from patients with acute ischemic stroke or transient ischemic attack from a multicenter stroke registry database in Korea. The association of hemoglobin concentration with 1-year stroke recurrence and composite vascular events was evaluated with respect to age, presence of cerebral artery stenosis, stroke severity, and stroke subtype. Results- Hemoglobin levels were inversely associated with stroke recurrence and composite vascular events. One-year rates of stroke recurrence and composite vascular events were significantly higher in patients with anemia or moderate anemia. In multivariable analyses, moderate anemia remained an independent predictor of stroke recurrence (adjusted hazard ratio, 1.43 [95% CI, 1.16-1.75]) and composite vascular events (adjusted hazard ratio, 1.26 [95% CI, 1.07-1.48]). Moderate anemia increased the risk of composite vascular events in patients with mild-to-moderate stroke severity (National Institutes of Health Stroke Scale score <16, P=0.01 for interaction). Conclusions- Hemoglobin concentration could be an independent predictor of stroke recurrence and composite vascular events.

Anemia management after acute brain injury

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Interestingly, the effects of red blood cell transfusions (RBCT) in moderately anemic patients remain controversial; although hemoglobin levels are increased, different studies observed only a modest and inconsistent improvement in cerebral oxygenation after RBCT and raised serious concerns about the risk of increased complications. Thus, considering this "blood transfusion anemia paradox", the optimal hemoglobin level to trigger RBCT in brain-injured patients has not been defined yet; also, there is insufficient evidence to provide strong recommendations regarding which hemoglobin level to target and which associated transfusion strategy (restrictive versus liberal) to select in this patient population. We summarize in this review article the more relevant studies evaluating the effects of anemia and RBCT in patients with an acute neurological condition; also, we propose some potential strategies to optimize transfusion management in such patients.