Smoking by husbands is associated with an increased occurrence of stroke among their non-smoking wives, according to a new study.

“Growing evidence suggests that exposure to environmental tobacco smoke may have deleterious cardiovascular effects,” Dr. Xiao Ou Shu, of Vanderbilt University, Nashville, Tennessee, and colleagues write in the American Journal of Epidemiology. “Few studies have investigated environmental tobacco smoke exposure in relation to stroke.”

The researchers looked into husbands’ smoking status and the prevalence of stroke among Chinese women non-smokers in Shanghai. The team notes that two thirds of men, but few women, in the region smoke.

Included in the analysis were 60,377 women between the ages of 40 and 70 years. In-person interviews were conducted in order to obtain data on husbands’ smoking status and history of physician-diagnosed stroke.

The survey showed that 32,287 women (54 percent) were living with a husband who was a current smoker. A total of 5108 (9 percent) were living with a husband who was a former smoker. Overall, 526 cases of stroke were reported.

Analysis showed that women living with a current smoker had a 47 percent higher risk of stroke compared to women married to a never-smoker. The risk was not significantly higher among women married to a former smoker.

“The odds of stroke increased with increasing number of cigarettes the husbands smoked per day,” Shu and colleagues write. Compared with women whose husbands had never smoked, those whose husbands were current smokers had a 28 percent to 62 percent increased risk of having a stroke, depending on how much the husband smoked.

The odds of stroke also increased with increasing duration of husbands’ smoking, according to the team.

“Education about the health consequences of tobacco use and exposure to environmental tobacco smoke is urgently needed in China, a country with more than 300 million smokers,” they conclude.

SOURCE: American Journal of Epidemiology, February 1, 2005.