Hospital-acquired anemia (HAA) is a fairly common condition associated with poor patient outcomes and increased hospital resource utilization (1). Preventing HAA demands a team approach and the clinical lab is a key player, since chronic phlebotomy-associated blood loss may lead to anemia. Labs can help limit diagnostic blood loss by implementing strategies that reduce the amount of blood required for testing and encourage appropriate test ordering. Improvements in these areas increase patient safety by reducing the risk of iatrogenic anemia as well as the need for blood transfusion.
What is HAA?
Anemia is a condition of decreased red blood cells (RBC) or hemoglobin due to blood loss, decreased RBC production, or increased RBC breakdown. HAA develops as a result of hospitalization in patients who have a normal hemoglobin level on admission and can be categorized as mild (Hgb < 11.0 g/dL), moderate (Hgb 9.1 – 11.0 g/dL), or severe (Hgb < 9.0 g/dL) (2).
What are the risk factors for HAA?
Every hospitalized patient is at risk for developing HAA, but the longer the stay the greater the risk (1). Neonatal, geriatric, and malnourished patients are predisposed to higher risk. HAA also frequently occurs in critically ill patients, those with a lower body mass index, and those suffering from long-term or serious illnesses such as kidney disease, cancer, or diabetes.
How does diagnostic blood loss contribute to HAA?
The development of HAA is multifactorial. Frequent and/or large blood draws for diagnostic testing have been identified as major contributing factors (3, 4). Normal bone marrow can compensate for blood loss associated with daily draws in most hospitalized patients, but patients with bone marrow suppression or other conditions affecting blood production may become anemic. Estimates for average daily diagnostic blood loss in hospitalized patients ranges from approximately 12 mL per day in general medicine wards to 40–50 mL per day in intensive care units (ICU), the latter being higher because critically ill patients typically require more testing (5). ICU patients with an indwelling catheter can lose up to 900 mL of blood during their hospital stay because a discard tube is required to flush the line before sample collection (5). This degree of phlebotomy-associated blood loss occurs most often in patients with long-term ventilation, coagulation disorders, or those who have undergone surgery. Patients admitted for acute myocardial infarction also experience substantial phlebotomy-associated blood loss. One study suggests that for every 50 mL of blood collected during hospitalization, the risk of developing HAA increases by 20% (6).
Does HAA affect patient outcomes?
A growing body of evidence suggests that patients with normal hemoglobin levels on hospital admission who subsequently develop HAA have increased risk of morbidity and mortality compared with those who do not (1, 6). These patients also experience increased length of stay and consume more hospital resources (1). Treatment of severe HAA in critically ill patients may involve RBC transfusion. This carries significant risk and may lead to additional complications.
Are there lab-based interventions to prevent HAA?
Clinical labs play an important role in decreasing phlebotomy-associated blood loss and preventing HAA (Table 1). In general, hospital labs collect up to 12 times more blood than the required analytical volume, with the majority of the sample being discarded (7). Studies suggest that most labs can decrease collection volumes without compromising their ability to report reliable and timely results (7). Using small volume blood collection tubes for at-risk populations, drafting a minimum sample volume chart for each test, and using previously collected samples for “add on” tests where appropriate are simple lab-based interventions to reduce diagnostic blood sampling volume and waste. Other blood conservation strategies include increasing the use of point-of-care testing in certain settings and monitoring blood volumes drawn from susceptible patient populations.
Tackling inefficient test ordering practices can also help reduce diagnostic blood loss and transfusion requirements. Labs can improve test utilization by providing more guidance for test selection, notifying physicians of duplicate orders, and eliminating standing orders. In addition, educating clinicians about the consequences of phlebotomy overdraws and encouraging batched test orders (so the same blood sample can be used for all tests in the batch) promotes a team approach toward blood conservation.
Recent advances in blood collection techniques and analytical instrumentation have reduced test volume requirements considerably, decreasing the risk of phlebotomy-induced HAA. Clinical labs can reduce this risk further by modifying routine practices as described in this article. Implementing these proactive blood management strategies not only increases patient safety but also reduces the cost of care.
References
1. Koch CG, Li L, Hixson ED, et al. Hospital acquired anemia: Prevalence, outcomes, and healthcare implications. J Hosp Med 2013;8:506–12.
2. Ahmed AH. Prevention and management of hospital-acquired anemia. Hosp Med Clin 3 2014;e71–84.
3. Thavendiranathan P, Bagai A, Ebidia A, et al. Do blood tests cause anemia in hospitalized patients? The effect of diagnostic phlebotomy on hemoglobin and hematocrit levels. J Gen Intern Med 2005;20:520–4.
4. Lin JC, Strauss RG, Kulhavy JC, et al. Phlebotomy overdraw in the neonatal intensive care nursery. Pediatrics 2000;106:E19.
5. Smoller BR, Kruskall MS. Phlebotomy for diagnostic laboratory tests in adults. Pattern of use and effect on transfusion requirements. N Engl J Med 1986;314:1233–5.
6. Salisbury AC, Alexander KP, Reid KJ, et al. Incidence, correlates and outcomes of acute, hospital-acquired anemia in patients with acute myocardial infarction. Circ Cardiovasc Qual Outcomes 2010;3:337–46.
7. Dale JC, Ruby SG. Specimen collection volumes for laboratory tests: A College of American Pathologists study of 140 laboratories. Arch Pathol Lab Med 2003;127:162–8.
Jaime Noguez, PhD, DABCC, is the assistant director of clinical chemistry at University Hospitals Case Medical Center and assistant professor of pathology at Case Western Reserve University in Cleveland, Ohio. +Email: [email protected]
CLN's Patient Safety Focus is sponsored by ARUP Laboratories
