HealthDay News — Over time, quitting smoking can reduce smokers’ risk for sudden cardiac death to levels on par with those who have never smoked, results from the Nurses’ Health Study suggest.
Risk for sudden cardiac death was significantly greater among smokers compared with those who never smoked at 30-year follow-up (HR 2.44, 95% CI 1.80 to 3.31), Roopinder Sandhu, MD, of the University of Alberta in Edmonton, and colleagues from Brigham & Women’s Hospital and the Harvard School of Public Health, Boston reported in Circulation.
Elevated risk was also observed in past smokers (HR 1.40, 95% CI 1.10 to 1.79), but this risk declined as the duration of smoking cessation increased, and within 20 years reached a level of risk comparable to those who never smoked.
“Our data reinforces the important concept that sudden cardiac death risk associated with cigarette smoking is modifiable,” the researchers wrote.
Sandhu and colleagues prospectively examined the correlation between cigarette smoking and smoking cessation on the risk of sudden cardiac death among 101,018 participants in the Nurses’ Health Study without CHD, stroke, or cancer at baseline in 1980.
During 30 years of follow-up, the researchers identified 351 SCD events confirmed using medical records, autopsy reports and interviews with family members. After controlling for coronary risk factors, current smokers had a significant 2.44-fold increased risk of SCD compared with never smokers.
Among current smokers, the quantity of cigarettes smoked daily and smoking duration were significantly linearly linked to SCD risk in multivariate analysis (P<0.0001 for both trends).
These associations persisted after researchers adjusted for several coronary heart disease risk factors, including age, diabetes, hypertension, hypercholesterolemia, BMI, alcohol use, physical activity, menopausal status and postmenopausal hormone use, use of aspirin, multivitamins and vitamin E and family history of MI.
SCD risk was significantly increased even with small-to-moderate amounts of cigarette consumption — those who smoked one to 14 cigarettes per day had a 1.84-fold increased risk (95% CI: 1.16-2.92).
Every 5 years of continued smoking was associated with an 8% greater risk of sudden cardiac death (HR 1.08; 95% CI:1.05-1.12).
After quitting, however, there was a linear decrease in SCD risk over time. After 20 years of cessation, the risk was equivalent to that of a never smoker among both past smokers (HR 0.45; 95% CI: 0.31-0.64) and those who had never smoked (HR 0.40; 95% CI: 0.30-0.54).
The reduction in risk was more rapid among women who did not develop coronary heart disease than those who did — less than five years vs.15 to 20 years.
“A dose-dependent relationship between smoking and SCD was observed, and even small-to-moderate quantities of daily smoking were associated with SCD risk,” the researchers wrote. “Efforts to prevent SCD among women should consider aggressive strategies for smoking cessation among all women.”
The study population was comprised of mostly white, female nurses, so findings may not be generalizable to other populations, the researchers wrote. Other study limitations include the self-reported nature of cigarette consumption, lack of information about CHD severity during follow-up, and the potential for residual or unmeasured confounding.