Docs slow to get with the guidelines on blood cultures for pneumonia

By Megan Brooks

NEW YORK (Reuters Health) - Blood cultures are still routinely obtained in adults admitted to U.S. hospitals with community-acquired pneumonia, despite clinical practice guidelines that advise limiting blood cultures to only the sickest patients, new research finds.

Routine blood cultures for all hospitalized CAP patients have "limited utility, and false-positive results lead to inappropriate antimicrobial use and longer hospital stays," note Dr. Anil Makam from UT Southwestern Medical Center, Dallas and colleagues in a Research Letter in JAMA Internal Medicine March 10.

As a result, practice guidelines that promoted obtaining blood cultures in all such patients were modified in 2005 to recommend routine collection only for patients with severe CAP.

Yet, they appear to be slow catching on.

"We were surprised to find that patients with the greatest disease severity were no more likely to have cultures collected, and patients admitted to the ICU actually had lower odds of obtaining cultures. These latter two groups of patients are most likely to benefit from this diagnostic test," Dr. Makam told Reuters Health by email.

The investigators used data from 2007 through 2010, from the National Hospital Ambulatory Medical Care Surveys (NHAMCS), to assess patterns of obtaining cultures in adults hospitalized with CAP after the recommendations were revised.

The analysis included 1487 visits, representing 5.1 million emergency department visits by adults with CAP. It showed that the proportion of blood cultures collected in hospitalized CAP patients increased from 29% in 2002 to 51% in 2010, a 73% relative increase (p=0.03 for trend).

On multivariate analysis, disease severity did not predict culture collection, and ICU admission was associated with lower odds of blood culture.

The investigators say one reason for the increase in blood cultures in the CAP population might be the PN-3b measure announced in 2002 by the Centers for Medicare & Medicaid Services and the Joint Commission on Accreditation of Healthcare Organizations. This measure mandated that if a culture is collected in the emergency department, it should be done before an antibiotic is given.

"This measure may encourage providers to reflexively order cultures in all patients admitted with community-acquired pneumonia in whom antibiotic administration is anticipated, even though cultures are strongly indicated in only the sickest patients," the investigators say.

"Given rising trends in obtaining cultures in low-risk patients, we advocate for the Joint Commission on Accreditation of Healthcare Organizations and Centers for Medicare & Medicaid Services to reexamine this measure with consideration of eliminating it entirely to discourage overuse," they advise.

They conclude, "Further attention is warranted to the judicious use of blood cultures in the management of pneumonia."

Dr. Makam told Reuters Health, "For clinicians, the take home message is that blood cultures are useful diagnostic tests in the sickest patients and in those with certain high-risk features, but when applied to a broader population, blood cultures have limited utility at the expense of potential harms and added costs. For policy makers, our study suggests that once a performance metric is implemented, it can be incredibly challenging to reverse its effects, making it ever so important to get them right the first time around."

SOURCE: http://bit.ly/PkQqqG

JAMA Intern Med 2014.

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