Middle-age and older women who avoid smoking, exercise regularly, follow a healthy diet, and maintain a healthy weight cut their risk of sudden cardiac death by 92%, compared with those who do not, according to a report in the July 6 JAMA.
If it is assumed that these four factors – smoking, lack of exercise, a poor diet, and obesity – play a causal role in sudden cardiac death (SCD), then approximately 80% of these deaths are preventable among women without diagnosed coronary heart disease, said Stephanie E. Chiuve, Sc.D., of the division of preventive medicine, Brigham and Women’s Hospital, Boston, and her associates.
In what they described as the first study to examine the combination of four lifestyle factors and risk of SCD, the investigators used data collected in the Nurses’ Health Study on 81,722 women who were aged 30-55 years at baseline in 1976. The study subjects were assessed biennially for smoking status, weight, menopausal status, use of medications, and physician-diagnosed disease, and were evaluated at longer intervals for diet and physical activity, over a total follow-up of 26 years (1984-2010).
The mean age at final follow-up was 72 years. There were 321 cases of SCD during follow-up.
A low-risk lifestyle was inversely related with SCD risk. The absolute risks of SCD were 22 cases/100,000 person-years with no low-risk lifestyle factors, 17 cases with one low-risk factor, 18 cases with two low-risk factors, 13 cases with three factors, and 16 cases with four.
Compared with women who had no low-risk lifestyle factors, who constituted 3% of the cohort, those with all four low-risk factors (who comprised 8% of the cohort) had a relative risk of 0.08 for SCD.
Women who followed all four low-risk lifestyle factors "had a 92% lower risk of SCD" compared with women with none of the low-risk lifestyle factors. "If these associations are causal, 81% of SCD within this cohort may have been prevented if all women adhered to a low-risk lifestyle," Dr. Chiuve and her colleagues said.
Extrapolating these results to the general U.S. female population, "Among women without diagnosed coronary heart disease, in whom the majority of SCD events occur, it is possible that 79% of SCD may be attributed to unhealthy lifestyle practices," they said (JAMA 2011;306:62-9).
Conversely, widespread adoption of a healthy lifestyle would "make a substantial impact" on reducing sudden cardiac death.
Primary prevention of SCD is a particular concern for women, who are half as likely as men to show left ventricular dysfunction and two-thirds less likely to be diagnosed as having coronary heart disease before SCD occurs. Women are therefore less likely to receive beta-blocker therapy or an implantable cardioverter-defibrillator to prevent the SCD.
This study was limited in that the NHS involved mostly white, well-educated, female health professionals, so the findings may not be generalizable to men or to people of other ethnicities.
The study was supported by the National Institutes of Health and the American Heart Association. An associate of Dr. Chiuve reported ties to the nutrition advisory board for UNO’s restaurant.