June 12, 2007 -- Having a high or low red blood cell count before major surgery may affect postsurgery deaths in adults aged 65 and older.
That's according to a new study published in The Journal of the American Medical Association.
The study is based on the medical records of more than 310,000 U.S. veterans aged 65 and older.
Between 1997 and 2004, the veterans got major surgery that didn't involve their hearts. They had their red blood cell counts measured up to three months before their operations.
The researchers included Wen-Chih Wu, MD, of Brown University's medical school and Rhode Island's Providence Veterans Affairs Medical Center.
They found that veterans with abnormally high or low red blood cell counts before surgery were more likely to die or have a heart attack in the month after surgery.
The findings even applied to patients with mildly high or low red blood cell counts before surgery. Those with extremely high or low red blood cell counts were at greater risk.
Risk in Perspective
Before surgery, nearly 57% of the patients had normal red blood cell counts, almost 43% had low red blood cell counts (anemia), and less than 1% had high red blood cell counts (polycythemia).
The study shows that for every percentage point above or below the normal red blood cell count range before surgery, patients were 1.6% more likely to die in the 30 days after surgery.
But the study doesn't prove that abnormal red blood cell counts directly influenced patients' postsurgery deaths or heart attacks.
Patients with polycythemia were more likely to be smokers and to have conditions including chronic obstructive pulmonary disease (COPD), the researchers note.
Wu's team considered such factors in analyzing the data. Their findings held.
However, Wu's team notes that abnormal red blood cell counts may be a marker -- but not a cause -- of postsurgery risk.
Since the veterans were mainly white men, the findings may not apply to other groups of people aged 65 and older.
Fixing the Problem?
It remains to be seen whether correcting low or high red blood cell counts would be beneficial to patients. The study didn't explore that issue.
However, an editorial published with the study suggests caution in correcting older adults' abnormal red blood cell counts before major surgery.
Until further studies are done, "the community of clinicians caring for patients preoperatively should learn from these experiences and resist the urge to 'not just stand there -- but do something,'" write editorialists Farhood Farjah, MD, and David Flum, MD, MPH.
Farjah and Flum work in Seattle at the University of Washington's surgery department. Flum is also a contributing editor for The Journal of American Medical Association.