Anemia Increases Cardiac Arrest, Stroke Risk in COVID-19 Admissions

Sung-Min Cho, DO

Credit: LinkedIn

Moderate-to-severe anemia was linked to an elevated risk of cardiac arrest or stroke, compared with a normal hemoglobin (Hb) level, in an international registry of patients with acute COVID-19 infection in the intensive care unit (ICU).¹

These data were determined by Cox proportional hazards regression analysis, which assessed the time to stroke or cardiac arrest by anemia status using death as a competing risk, across a registry of patients admitted with COVID-19 to 370 international ICUs.

“Anemia status persisted as an independent risk factor for the composite cardiac arrest and stroke outcome after adjusting for both the pre-selected and expanded set of covariates observed to increase with anemia severity,” wrote the investigative team, led by Sung-Min Cho, DO, division of neuroscience critical care, Johns Hopkins University School of Medicine.

Anemia has been correlated with an increased risk of cardiac arrest and stroke, which are frequent complications of COVID-19 infection.² Prior literature has linked Hb levels to COVID-19 infection prognosis, with more severe disease worsening outcomes.³

The COVID-19 Critical Care Consortium is an international network created to collect multicenter observational data on critically ill patients with COVID-19. Using the database, this retrospective analysis investigated the link between Hb levels and a composite outcome of cardiac arrest or stroke in patients with COVID-19 and respiratory failure.¹

All patients infected with active COVID-19 requiring ICU admission between January 2020 and September 2022 were included in the analysis. Patients were required to be diagnosed with cardiac arrest or stroke up to 30 days after ICU admission. A total of 6926 patients were identified, of which 760 patients (11.0%) experienced stroke (2.0%) or cardiac arrest (9.4%).

Anemia at baseline was calculated as the average of 1–3 Hb measurements collected up to 3 days after ICU admission. Patients were categorized as normal (Hb ≥12.0 g/dL for women; ≥13.5 g/dL for men), mild (Hb 10.0–11.9 g/dL for women; 10.0–13.4 g/dL for men), moderate (Hb ≥8.0 for women, <10.0 g/dL for men), and severe (Hb <8.0 g/dL for women and men).

Among 4926 patients with a hemoglobin measurement at ICU admission, 1863 (26.9%) had normal hemoglobin, 2133 (30.8%) had mild anemia, and 930 (13.4%) had moderate-to-severe anemia.

Upon analysis, composite cardiac arrest or stroke outcomes increased with anemia severity. Cardiac arrest or stroke occurred in 12.8% of patients with normal hemoglobin levels, 13.3% of patients with mild anemia, and 16.7% of patients with moderate-to-severe anemia.

The Cox proportional hazards models for survival analysis of cardiac arrest and stroke revealed moderate-to-severe anemia led to a 32% increase in the risk of cardiac arrest or stroke (hazard ratio [HR], 1.32; 95% CI, 1.05–1.67). These data were adjusted for country income status, pandemic era, sex, comorbidities, mechanical ventilation (MV), and extracorporeal membrane oxygenation (ECMO).

In their conclusion, Cho and colleagues pointed to recent studies suggesting COVID-19 infection could increase the risk of cardiac arrest and stroke for up to a year after initial infection. They called for future studies to understand better this long-term risk.

“Thus, future research should seek to better understand the long-term effects of hemoglobin levels on composite cardiac arrest and stroke outcome in patients with COVID-19,” they wrote.

References

1. _{Feng SN, Kelly TL, Fraser JF, et al. Impact of Hemoglobin Levels on Composite Cardiac Arrest or Stroke Outcome in Patients With Respiratory Failure Due to COVID-19. Crit Care Explor. 2024;6(9):e1143. Published 2024 Aug 22. doi:10.1097/CCE.0000000000001143}
2. _{Tao Z, Xu J, Chen W, et al. Anemia is associated with severe illness in COVID-19: A retrospective cohort study. J Med Virol. 2021;93(3):1478-1488. doi:10.1002/jmv.26444}
3. _{Oh SM, Skendelas JP, Macdonald E, et al. On-admission anemia predicts mortality in COVID-19 patients: A single center, retrospective cohort study. Am J Emerg Med. 2021;48:140-147. doi:10.1016/j.ajem.2021.03.083}