DURHAM, N.C. - A study by Duke University Medical Center researchers has found that women do not derive the same long-term quality-of-life benefits as men following coronary artery bypass surgery. This conclusion was evident even after the researchers statistically adjusted their data to allow for the greater number of preoperative risk factors in women than in men.
The researchers speculate that there may be two reasons for this clear gender discrepancy - either women may not experience the same level of physical benefits from the surgery as men, or their lowered quality of life is less related to cardiac health than men.
The results of the Duke study were published today (Nov. 24, 2003) in the journal Psychosomatic Medicine. The research was support by the National Institutes of Health and the American Heart Association (AHA).
"We know that in general women receiving bypass surgery are sicker, older, more likely to live alone and have other preoperative differences that would appear to explain a compromised quality of life," said lead author Barbara Phillips-Bute, Ph.D., assistant research professor in department of anesthesiology. "However, when we control for all these factors, a significant difference still exists."
Both the American College of Cardiology and the AHA have issued guidelines stating that when physicians and patients discuss the option of surgery, quality of life should be considered as an important factor along with survival, Phillips-Bute said. When all bypass patients are taken together, the surgery does improve quality of life, she continued, adding however that little is known about the gender differences.
To better understand these gender differences, the Duke team enrolled in a clinical trial 280 patients (96 women and 184 men) who were to receive bypass surgery.
All were given a battery of tests that measured quality of life and cognitive status prior to surgery and one year later. The quality-of-life tests measured such factors as activities of everyday life, social support, general health perception, depression and anxiety, while the cognitive tests measured such areas as short-term memory, psychomotor skills, concentration and attention.
For their analysis, the team then statistically controlled for such patient characteristics as age, years of education, marital status, other diseases, hypertension, diabetes, race and baseline quality of life and cognitive scores.
"The female patients showed significantly worse outcomes than male patients after one year in several key areas of quality of life," Phillips-Bute said. "After adjusting for the baseline differences, women were at greater risk for mental difficulties and anxiety, as well as the perception that their ability to perform the activities of everyday life had diminished since the surgery
"In many of the domains, women start worse than men, finish worse than men, and have worse recovery profiles than men," she concluded.
While there was a significant difference in the quality-of-life measurements, the impairments to cognitive function attributable to the surgery were similar between men and women.
Since the differences between the genders cannot be totally explained by their pre-operative characteristics, the researchers offer two possible explanations.
First, studies have shown that women do not always receive the same surgical benefit as men, Phillips-Bute explained, adding that women's arteries are smaller and that the vessels used in the bypass do not tend to last as long. Additionally, women experience less relief from angina and breathlessness, have more bedridden days and tend to be taking more cardiac medications than men.
"The impaired quality of life we find in our analysis may be related to the generally poorer prognosis for women after bypass surgery," Phillips-Bute said.
Secondly, the diminished quality of life reported by women may be due to factors other than cardiac health.
"If the causes of lower quality of life in women are due more to environment or personality, this could account for the differences we saw in our analysis," she continued. "If this is the case, interventions other than bypass surgery would be needed for women to experience the same improvements as men."
Other members of the Duke team included Joseph Mathew, M.D., James Blumenthal, Ph.D., Kathleen Welsh-Bohmer, Ph.D., William White, Daniel Mark, M.D., Kevin Landolfo, M.D., and Mark Newman, M.D. All are members of the Duke Neurological Outcome Research Group and the Cardiothoracic Anesthesiology Research Endeavors group.