Background: Anemia is frequent in patients with cardiovascular disease and is significantly associated with poor prognosis. However, the prognostic significance of anemia in hypertensive crisis remains unknown. We conducted this study to determine whether anaemia is a risk factor for all- cause mortality in patients with hypertensive crisis visiting the emergency department (ED). Methods: This retrospective study included patients who visited the ED in 2024 for hypertensive crisis, which was defined as systolic blood pressure ≥180 mmHg or dia- stolic blood pressure ≥110 mmHg. A total of 5,512 patients whose serum haemoglobin levels were checked were included in this study and were classified into three groups according to their serum haemoglobin levels at admission to the ED: moderate/severe anaemia (haemoglobin <11 g/dL), mild anaemia (haemoglobin 11 to <13 g/dL in men and 11 to <12 g/dL in women), and non-anaemia (haemoglobin ≥13 g/dL in men and ≥12 g/dL in women). Results: Among 5,512 patients, 665 (12.1%) and 668 (12.1%) were classified into the moderate/ severe anaemia and mild anaemia groups, respectively. The three-year all-cause mortality rates in the moderate/severe anaemia, mild anaemia, and non-anaemia groups were 46.0, 29.2, and 12.0%, respectively. After accounting for relevant covariates, patients with moderate/severe anaemia group (hazard ratio [HR], 2.15; 95% confidence interval [CI], 1.75–2.64) and mild anaemia group (HR, 1.32; 95% CI, 1.07–1.63) had a higher risk of 3-year all-cause mortality than the non-anaemia group.

Conclusion: Anaemia is independently associated with 3-year all-cause mortality in patients with hypertensive crisis. A comprehensive therapeutic approach through more in-depth examin- ation and close follow up are required for patients with hypertensive crisis with anaemia.