Hospital-acquired anemia common among ICU patients

by American Association of Critical-Care Nurses

edited by Sadie Harley, reviewed by Andrew Zinin

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Critically ill patients often develop anemia in the hospital, whether their hemoglobin levels are considered low upon admission or fall during their stay. Although seemingly minor compared to their other health issues, the blood loss is directly tied to a variety of poor patient outcomes.

A single-site study at a southwest Florida hospital found that 64% of patients in the intensive care unit (ICU) developed hospital-acquired anemia (HAA), which the research team defined as a decline of 10% or greater in hemoglobin levels while in the ICU. ICU stays were significantly longer for these patients than for those who did not have HAA.

The study, "Determining the Prevalence of Hospital-Acquired Anemia in the Intensive Care Unit at a Florida Hospital" published in the American Journal of Critical Care (AJCC), was conducted at Lee Memorial Hospital, Fort Myers, Florida, a 336-bed acute care hospital established in 1916. It is part of Lee Health, a community-focused nonprofit health system that provides care throughout southwest Florida.

Co-author Darnella Adams, DNP, MSN, RN, PCCN, is a clinical nurse and chair of the hospital's Nursing Research and Evidence-Based Practice Council.

"Hospital-acquired anemia is a serious, often overlooked threat that directly drives up ICU length of stay, morbidity and mortality," she said. "Drop by drop, vial by vial, nurses can lead blood-conservation initiatives, reduce the incidence of anemia and improve patient outcomes."

A decline in hemoglobin levels is a common iatrogenic effect of hospitalization, especially in ICUs. Blood loss, whether from trauma, procedures or phlebotomy for routine lab tests, is one of the primary causes of HAA.

The study began with a convenience sample of medical records for 151 patients admitted to the ICU over a six-month period, from Jan. 1 to June 30, 2024. After exclusion criteria, such as receiving any packed red blood cells or lacking comparison lab values, were applied, the research team examined data for 108 patients.

Recognizing that critically ill patients, especially those over age 65, may already possess a low baseline hemoglobin level, the research team chose to conservatively define HAA as a 10% or greater decline in a patient's hemoglobin level while in the ICU.

Upon ICU admission, 55% of the patients (59 of 108) met the American Society of Hematology criteria for anemia. Of those who did not have anemia when admitted to the ICU, more than half (55% of 49 patients) had hemoglobin levels fall below those national thresholds while in the ICU. Overall, 64% experienced HAA.

Although the study defined HAA as a decline of 10% or greater in hemoglobin levels, patients with HAA experienced declines up to 30%. In contrast, patients without HAA had a mean decline in hemoglobin levels of 4%.

Of particular concern is the finding that more than 50% of patients who entered the ICU with normal hemoglobin levels had developed HAA by the time of discharge from the unit. This finding of new-onset anemia highlights the aggressive nature of iatrogenic blood loss in the critical care environment.

For the total study population, the mean ICU length of stay was 4.9 days. For patients with HAA, the mean ICU stay was 5.9 days compared with 3.3 days for those who didn't develop HAA.

When six patients with exceptionally long ICU stays and steep declines in their hemoglobin levels of greater than 40% were excluded from the analysis, the difference remained statistically significant: a mean ICU stay of 5.1 days for those in the HAA group and 2.8 days for those whose hemoglobin did not decrease more than 10%.

The high prevalence of HAA (64%) in the study population justifies the adoption of evidence-based conservation strategies. Implementing the use of small-volume phlebotomy tubes, using closed blood sampling systems and practicing fluid stewardship to avoid hemodilution are actionable steps for nursing teams to improve patient outcomes and reduce the iatrogenic burden.

More information

Darnella Adams et al., Determining the Prevalence of Hospital-Acquired Anemia in the Intensive Care Unit at a Florida Hospital, American Journal of Critical Care (2026). DOI: 10.4037/ajcc2026429

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Critical care medicineHospital medicine Provided by American Association of Critical-Care Nurses Who's behind this story?

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