Findings may lead clinical pathology laboratories to update phlebotomy guidelines
What is the proper quantity of blood to draw from a patient for medical laboratory testing purposes? That question has been debated regularly for decades by pathologists and clinical laboratory scientists. Now a recent study shows a connection between blood draw practices and hospital-acquired anemia in patients with acute myocardial infarction.
The findings of this study serve as evidence that the quantity of blood drawn from hospital inpatients during phlebotomy procedures can potentially have a negative affect, at least for patients with certain health conditions. This study also shows how more detailed research can produce findings that lead to a change in clinical laboratory testing practices.
Researchers reviewed the electronic medical records of 17,676 acute myocardial infarction (AMI) patients from 57 hospitals in the U.S. for the years 2000 through 2008. It was determined one in five of the AMI patients had developed prognostically important anemia—classified as moderate to severe—during their hospital stay. Patients in the study had no anemia upon admission to the hospital and had no bleeding complications to account for the blood loss.
Anemia is a condition marked by a deficiency of red blood cells or of hemoglobin in the blood, resulting in reduction of oxygen delivery within the body. HAA can often persist for months and can lead to poorer patient outcomes and higher mortality.
Cardiologist Mikhail N. Kosiborod, M.D., was the senior author of the study. He practices at St. Luke’s Hospital Heart and Vascular Institute and is an Associate Professor of Medicine at the University of Missouri in Kansas City. In a story published by HealthDay Reporter, Kosiborod pointed out, “This is not just a lab abnormality. These patients actually feel worse after they leave the hospital. Mortality is higher, too.”
As senior researcher for the team that studied the causes of hospital-acquired anemia among patients with acute myocardial infarction (AMI), cardiologist Mikhail N. Kasiborod, M.D., noted that one in five AMI patients had acquired clinically-significant anemia during their hospital stay. (Photo copyright Journal of the American Medical Association.)
The researchers found that mean phlebotomy volume varied significantly within the 57 hospitals in the study. “Drawing blood in a hospital is typically a very common occurrence, particularly in the intensive care unit,” noted Kosiborod. “Some hospitals draw more blood than others.” Variations in the quantity of blood drawn during phlebotomy procedures led the researchers to the hypothesis that there was a connection between the amount of diagnostic blood loss and HAA.
According to the study, diagnostic blood loss for the average patient who developed moderate-to-severe anemia was 173.8 milliliters. (A unit of whole blood is 450 milliliters.) That was over twice the 83.5 milliliters of blood that was drawn from the average patient who did not develop the condition. The study further found that the risk of moderate to severe HAA increased by 18% for every 50 milliliters of blood drawn.
According to an abstract published online at PubMed.gov, as far back as 2004, multiple studies concerning diagnostic blood loss (DBL) have warned of the hazards of DBL and urged better practices. “The quality and economy of critical care could both be improved if blood losses due to phlebotomy and sampling from indwelling catheters for unnecessary diagnostic testing were curtailed,” the abstract states. It goes on to suggest that practice guidelines can help to break “bad diagnostic habits.”
Hospital-Acquired Anemia Raises Issues Of Poorer Patient Outcomes, Higher Costs
Poorer outcomes associated with HAA can also mean higher healthcare costs. “If you put the cost together with the issue of the hazard of patients developing hospital-acquired anemia, that’s pretty profound,” says Stephanie Rennke, M.D., Assistant Clinical Professor of Medicine at the University of California, San Francisco (UCSF). She was quoted in the HealthDay Reporter article. According to Rennke, who co-authored an editorial to accompany the HAA study, UCSF has already implemented changes to its blood test ordering protocol. ”We have to think before we order a test,” she stated.
Study Findings Could Lead To Promising Interventions To Reduce HAA
Clinical laboratory managers and pathologists should take note of another interesting aspect of this study of anemia in patients hospitalized with acute myocardial infarction. This study is an example of how researchers are studying the differences in care provided to patients who got better outcomes and comparing them to the care provided to patients who got worse outcomes. These findings will then be used to improve the standard of care.
Dark Daily expects that these types of evidence-based clinical studies will often identify how better physician utilization of medical laboratory testing can improve patient care. That will be positive for the laboratory medicine profession.
In the meantime, now that researchers have established a link between the quantity of blood drawn from hospitalized AMI patients and the incidence and severity of anemia, it is likely that this study may encourage hospital laboratories to review their current requirements for blood draws of AMI patients.
—Pamela Scherer McLeod