TUESDAY, June 12, 2007 (HealthDay News) -- Older men who have too few or too many red blood cells have a higher risk of dying after surgery than those who have the right amount, suggests new research.
The study found that the optimal hematocrit (a measure of red blood cells) for men over 65 was between 39 percent and 53.9 percent, and for every point above or below that normal range, a person's risk of dying within 30 days of non-heart-related surgery increased by 1.6 percent. That means someone with a preoperative hematocrit of 30 had a 14.4 percent higher risk of death than someone with a normal hematocrit level.
"When an elderly man undergoes non-cardiac surgery with a higher than normal or lower than normal red blood cell count, that poses a higher risk of postoperative cardiac events and death," said study author Dr. Wen-Chih Wu, a staff cardiologist and researcher at the Providence Veterans Affairs Medical Center, and an assistant professor of medicine at the Warren Alpert Medical School at Brown University in Providence, R.I.
Wu doesn't believe these findings can be applied to other populations, such as women or younger people. He said that's because older men often have a higher risk of heart disease and may be unaware when they go into surgery that they have underlying heart disease. To compensate for low levels of red blood cells -- which carry oxygen throughout the body -- the heart has to work harder, said Wu. Older people are also more at risk of having other underlying diseases, such as kidney disease, gastrointestinal bleeding or cancer, all of which can affect red blood cell levels.
The current study, which appears in the June 13 issue of the Journal of the American Medical Association, examined data from 310,311 veterans over the age of 65 who had non-cardiac surgeries. The study participants were nearly all male, and most were in their 70s. Forty-three percent had a hematocrit of less than 39 percent prior to surgery, while 0.2 percent had polycythemia, or a high hematocrit, before surgery.
The surgical procedures included in the study varied widely and included, but weren't limited to, hernia repair, knee or hip replacement, leg amputation, gallbladder removal, lung removal, repair of femur fracture and cancerous tumor removal.
Overall, 3.9 percent of the study group experienced a cardiac event, and 1.8 percent died within 30 days of surgery.
The risk of death went up if hematocrit levels deviated from normal, according to the study. For each percentage point above or below the normal range, the risk of mortality increased by 1.6 percent.
What Wu and his colleagues weren't able to learn from this study was if improving hematocrit levels would improve surgical outcomes.
"When you're not in the normal range, it's a pretty powerful indicator that there is something else going on," said Dr. Jay Brooks, chairman of hematology and oncology at the Ochsner Health System in Baton Rouge, La. "Doctors should look at why those levels aren't normal and see if there's something that's correctable before surgery."
Wu suggested that people should try to maintain their hematocrit level within the normal range, and that they should discuss what's normal for themselves with their doctor. For example, the range for men and women is different.
"Try to maintain your health as much as you can before any type of major surgery," advised Wu.
To learn more about hematocrit levels and how it's measured, visit the National Library of Medicine.