August 11, 2011 (Kansas City, Missouri) — Taking less blood from acute-MI patients for diagnostic tests may improve patient outcomes by reducing the risk of hospital-acquired anemia, a new study published online August 8, 2011 in the Archives of Internal Medicine suggests [1].
Multiple studies have shown that hospital-acquired anemia is associated with greater mortality and worse health status in patients with acute MI, but the relationship between diagnostic phlebotomy and the risk of hospital-acquired anemia had not been rigorously studied in this population, according to Dr Adam Salisbury (Saint Luke’s Mid-America Heart and Vascular Institute, Kansas City, MO) and colleagues.
Salisbury and colleagues analyzed records from 57 centers from in the Cerner Health Facts electronic medical records database. This database was ideal for studying the link between phlebotomy and hospital-acquired anemia because it contains detailed information on patients ' laboratory tests and patients ' hemoglobin levels across a variety of hospitals. The database included 17 676 acute-MI patients who were not anemic at admission. Each patient 's total diagnostic blood loss was estimated based on the standard volume for each tube type used to draw blood in that patient.
In the study, moderate to severe hospital-acquired anemia--a hemoglobin level decline from normal to <11 g/dL--was found in 3551 patients (20%). The mean volume of blood taken for diagnostics was higher in patients with anemia (173.8 mL) than in those who did not develop anemia (83.5 mL) (p<0.001). For every 50 mL of blood drawn, a patient 's risk of developing moderate to severe hospital-acquired anemia increased by18%. The risk was only slightly attenuated after multivariable adjustment.
The average blood loss per patient varied significantly among hospitals, from 53.0 mL to 109.6 mL for the entire cohort. The interhospital variability was even greater among patients with moderate to severe anemia,
References: 1. Salisbury AC, Reid KJ, Alexander KP, et al. Diagnostic blood loss from phlebotomy and hospital-acquired anemia during acute myocardial infarction. Arch Intern Med 2011; DOI:10.1001/archinternmed.2011.361. Available here.Abstract