AIM: Phlebotomy volume varies in heart attack patients; linked with anemia
In a study of more than 17,000 patients who were admitted to 57 hospitals for acute myocardial infarction (AMI), researchers found the mean phlebotomy volume was higher in patients who acquired anemia in the hospital compared to those who did not, according to study findings published Aug. 8 in the Archives of Internal Medicine.
Adam C. Salisbury, MD, of Saint Luke’s Mid America Heart and Vascular Institute in Kansas City, Mo., and colleagues found moderate to severe hospital-acquired anemia (HAA) developed in 3,551 patients out of 17,676 admitted to hospitals from Jan. 1, 2000, through Dec. 31, 2008 for heart attacks. For every 50 ml of blood drawn, investigators found the risk of moderate to severe HAA increased by 18 percent. Estimates of mean blood loss from phlebotomy for patients who acquired HAA were nearly 100 ml higher than estimates for those who did not develop HAA. Notably, researchers also found that mean phlebotomy volume varied widely across hospitals.
In an accompanying editorial, Stephanie Rennke, MD, and Margaret C. Fang, MD, MPH, both of the University of California, San Francisco, took particular interest in the findings that mean phlebotomy volume varied among hospitals, “suggesting that some blood tests may have been simply ‘routine’ and implying that reduction in the variability of care could potentially lead to reductions in HAA.”
Salisbury et al studied the association between phlebotomy and HAA using Cerner’s Health Facts database using de-identified data from electronic medical records during the eight-year period.
Patients were classified as having HAA if their initial hemoglobin level was higher than the diagnostic thresholds but their lowest hemoglobin level during hospitalization fell below the diagnostic threshold for anemia, according to the study. All patients hospitalized with a primary discharge diagnosis of AMI were included in the study, and comprehensive diagnostic blood loss was included in the data. Baseline patient characteristics, laboratory values, in-hospital treatments and complications of patients who developed moderate to severe HAA were compared with those who did not, according to the authors.
While one in five patients admitted for AMI developed moderate to severe HAA during their hospital stay, researchers found the mean hemoglobin values declined during hospitalization in both groups, but more so in those that acquired HAA.
“Diagnostic blood loss (DBL) was substantial, particularly among individuals with HAA, and varied widely across hospitals, suggesting that process-of-care differences may influence DBL,” the authors wrote. “It is important to note that DBL was independently associated with a higher risk of HAA and that this association remained robust after multivariable adjustment and in several sensitivity analyses.”
Salisbury and colleagues noted numerous factors which contribute to HAA, including age, sex, chronic kidney disease and acute inflammation from AMI, but noted that two additional factors specifically fall under the control of providers: prevention of periprocedural bleeding and minimization of phlebotomy.
“Our findings also indicate that reduction of blood loss from phlebotomy could be important to limit development and severity of HAA,” wrote Salisbury et al. “For example, we found that estimated phlebotomy volumes were dramatically lower with pediatric tubes, highlighting a promising intervention to limit DBL.
“In conclusion, blood loss from phlebotomy is substantial in patients with AMI, varies across hospitals and is independently associated with 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,” the authors concluded.
Rennke and Fang noted that the research of Salisbury et al could lead to promising interventions to reduce HAA.
"With the increasing evidence that healthcare 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," they wrote. "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."
Adam C. Salisbury, MD, of Saint Luke’s Mid America Heart and Vascular Institute in Kansas City, Mo., and colleagues found moderate to severe hospital-acquired anemia (HAA) developed in 3,551 patients out of 17,676 admitted to hospitals from Jan. 1, 2000, through Dec. 31, 2008 for heart attacks. For every 50 ml of blood drawn, investigators found the risk of moderate to severe HAA increased by 18 percent. Estimates of mean blood loss from phlebotomy for patients who acquired HAA were nearly 100 ml higher than estimates for those who did not develop HAA. Notably, researchers also found that mean phlebotomy volume varied widely across hospitals.
In an accompanying editorial, Stephanie Rennke, MD, and Margaret C. Fang, MD, MPH, both of the University of California, San Francisco, took particular interest in the findings that mean phlebotomy volume varied among hospitals, “suggesting that some blood tests may have been simply ‘routine’ and implying that reduction in the variability of care could potentially lead to reductions in HAA.”
Salisbury et al studied the association between phlebotomy and HAA using Cerner’s Health Facts database using de-identified data from electronic medical records during the eight-year period.
Patients were classified as having HAA if their initial hemoglobin level was higher than the diagnostic thresholds but their lowest hemoglobin level during hospitalization fell below the diagnostic threshold for anemia, according to the study. All patients hospitalized with a primary discharge diagnosis of AMI were included in the study, and comprehensive diagnostic blood loss was included in the data. Baseline patient characteristics, laboratory values, in-hospital treatments and complications of patients who developed moderate to severe HAA were compared with those who did not, according to the authors.
While one in five patients admitted for AMI developed moderate to severe HAA during their hospital stay, researchers found the mean hemoglobin values declined during hospitalization in both groups, but more so in those that acquired HAA.
“Diagnostic blood loss (DBL) was substantial, particularly among individuals with HAA, and varied widely across hospitals, suggesting that process-of-care differences may influence DBL,” the authors wrote. “It is important to note that DBL was independently associated with a higher risk of HAA and that this association remained robust after multivariable adjustment and in several sensitivity analyses.”
Salisbury and colleagues noted numerous factors which contribute to HAA, including age, sex, chronic kidney disease and acute inflammation from AMI, but noted that two additional factors specifically fall under the control of providers: prevention of periprocedural bleeding and minimization of phlebotomy.
“Our findings also indicate that reduction of blood loss from phlebotomy could be important to limit development and severity of HAA,” wrote Salisbury et al. “For example, we found that estimated phlebotomy volumes were dramatically lower with pediatric tubes, highlighting a promising intervention to limit DBL.
“In conclusion, blood loss from phlebotomy is substantial in patients with AMI, varies across hospitals and is independently associated with 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,” the authors concluded.
Rennke and Fang noted that the research of Salisbury et al could lead to promising interventions to reduce HAA.
"With the increasing evidence that healthcare 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," they wrote. "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."