Men over 65 with even slightly abnormal red blood cell counts either too low or too high are at greater risk of post-operative death or cardiac events following a major non-cardiac surgery, according to a new study by researchers at the Providence Veterans Affairs Medical Center and The Warren Alpert Medical School of Brown University.
Elderly patients are at risk for abnormal hematocrit values, or the number of red cells in the blood. These red cell counts are often too low, causing anemia, or too high, a sign of a condition called polycythemia. Elderly people are more prone to both anemia and polycythemia because they're more likely to have health problems that affect red blood cells, such as kidney disease, gastrointestinal bleeding, malnutrition or cancer. The elderly are also more likely to have heart disease, which makes them more vulnerable to the stresses of surgery and puts them at greater risk of post-operative heart attacks and other cardiac complications.
But results from this new study, published in the June 13 issue of JAMA, are the first to show that even slightly abnormal pre-operative red cell counts can have serious post-operative conse-quences. The results also bring new meaning to hematocrit tests: Even though virtually all pa-tients get this screening before major surgery, doctors had little guidance on how to interpret test results that fall just outside the normal range.
"Even though hematocrit tests are nearly universal before elective surgery, doctors don't have a reliable yardstick for gauging a normal or a mildly abnormal result. So the test, on many oc-casions, is not very helpful," said Wen-Chih Wu, M.D., lead author of the JAMA article, assistant professor of medicine at The Warren Alpert Medical School of Brown University, and staff car-diologist at the Providence Veteran Affairs Medical Center. "One of my biggest hopes for this research is that it eventually helps doctors better interpret hematocrit test results to improve pa-tient outcomes."
Wu and his colleagues set out to evaluate the prevalence of pre-operative anemia and poly-cythemia and their effects on 30-day post-operative outcomes for veterans. Wu and his team mined data from the Veterans Affairs National Surgical Quality Improvement Program to conduct their work, looking at medical data of 310,311 veterans aged 65 or older who underwent major non-cardiac surgery. These surgeries, which ranged from total knee replacements to pros-tate surgeries to hernia repairs, took place between 1997 and 2004 in 132 Veterans Affairs Medical Centers across the United States.