Evaluation of Hospital-Acquired Anemia and Contributing Factors in ICU Patients: A Retrospective Cohort Study

Objectives: Hospital-acquired anemia (HAA) is an important clinical problem that can adversely affect outcomes, particularly in critically ill patients. This study aimed to determine the incidence of hospital-acquired anemia in adult ICU patients and to evaluate its relation with diagnostic phlebotomy procedures and other etiologic factors. Methods: Data from 1170 adult ICU admissions between 1 January and 31 December 2024 were retrospectively reviewed and 321 patients were included in the analysis. The median age of the study cohort was 72 years (range: 18–102), with 45.2% females (n = 145) and 54.8% males (n = 176). The median ICU length of stay was 6 days (range: 3–29). Results: HAA developed in 35.8% of patients, while a decrease in hemoglobin levels was observed in 80.4%. Patients who developed HAA had significantly longer ICU stays and higher ferritin, CRP, and diagnostic phlebotomy (DP) volumes, while admission hemoglobin levels were lower compared with those without HAA (all p < 0.05). In multivariate analysis, a longer ICU stay, higher ferritin levels, lower admission hemoglobin levels and greater DP volumes were independently associated with the development of HAA. Conclusions: HAA was common in critically ill patients and was associated with several clinical and laboratory factors, including inflammatory burden, baseline hemoglobin level, ICU length of stay, and diagnostic phlebotomy volume. These findings suggest that HAA is a multifactorial process, with ICU length of stay, inflammatory status, baseline hemoglobin levels, and diagnostic phlebotomy volume all potentially contributing to its development.