Blood loss from increased use of phlebotomy (blood taken for diagnostic testing), in patients with acute myocardial infarction (heart attack), appears to be independently linked with the development of hospital-acquired anemia (HAA) according to a study first published Online by Archives of Internal Medicine, one of the JAMA/Archives journals, is part of the journal’s “Less Is More” series.

Patients with AMI are linked to a higher risk of mortality and worse health status if they had Anemia (low red blood cell count or low hemoglobin level) irrespective of whether their condition was chronic (present at hospital admission) or hospital-acquired, according to background research in the study. If strategies to reduce blood loss in high-risk patients are implemented, HAA might be preventable.

Blood loss from diagnostic phlebotomy is among the factors that could be linked with HAA, which has been linked in other patient populations with in-hospital declines in hemoglobin level and need for blood transfusion. The investigators wrote

“Blood loss from phlebotomy could be an actionable target for intervention.”

Data was analyzed from the Cerner Corp.’s Health Facts database, by Adam C. Salisbury, M.D., M.Sc., from Saint Luke’s Mid America Heart and Vascular Institute, Kansas City, Mo., and colleagues. From January 2000 to December 2008 records contained 17,676 patients who were admitted with AMI and no anemia from 57 hospitals. The investigators identified all phlebotomy events in patient records in order to measure blood loss.

By the laboratory tests ordered, they were able to determine, which type of hematology tubes were used and the blood volume each held. For each patient, researchers then multiplied these blood volumes by the number of tubes of each type that were collected during hospitalization. They also calculated the mean (average) blood drawn for every 24 hours of hospitalization, together with the mean phlebotomy volumes for each of the first 10 days of hospitalization.

Around 20% of patients (n = 3,551) developed moderate to severe HAA. Over the period of hospitalization, patient estimates of mean blood loss from phlebotomy (173.8 milliliters (mL), were nearly 100mL higher than estimated blood loss in patients didn’t develop moderate to severe HAA (83.5mL). The volume of diagnostic blood drawn was linked with developing moderate to severe HAA.

The relative risk for HAA developing rose by 18% for each 50 mL of blood drawn; the relationship continued when investigators modified the date for site and potential confounders. Across hospitals the average volume of blood drawn varied significantly.

The authors wrote,

“In conclusion, blood loss from phlebotomy is substantial in patients with AMI, varies across hospitals, and is independently associated with the development of HAA.

Studies are needed to test whether strategies that limit both the number of blood draws and the volume of blood removed for diagnostic testing can prevent HAA and improve clinical outcomes in patients with AMI.”

An additional commentary by Stephanie Rennke, M.D., and Margaret C. Fang, M.D., M.P.H., both from the University of California, San Francisco, examined the report by Salisbury and colleagues in the larger context of patient safety in hospitals. Rennke and Fang write,

“Of particular interest was the finding that the mean phlebotomy volume in patients varied widely across individual hospitals, suggesting that some blood tests may have simply been ‘routine’ and implying that reduction in the variability of care could potentially lead to reductions in HAA.”

Since the publication of an Institute of Medicine study on the topic in 1999, they cite increased attention to patient safety. Reenke and Fang explain this focus,

“has led hospitals to test and implement system-wide interventions, some of which have been found to be effective in reducing the rates of hospital-acquired complications.”

Pointing to a Michigan Health and Hospital Association Keystone program as an example, which seemed to decrease rates of hospital-acquired infections and subsequent hospital deaths.

The investigators write,

“With the increasing evidence that health care system interventions can reduce or prevent many hospital-acquired complications, efforts to implement effective strategies to make medical care safer and more effective are crucial.

As Salisbury et al highlight in their study, HAA could potentially be considered a hazard of hospitalization. Investigations on how to modify this risk (e.g., through reducing unnecessary phlebotomy or reducing the volume of blood obtained during a hospitalization) could provide important insights into how to reduce anemia in the hospital and improve the value and appropriateness of care.”

Written by Grace Rattue