The 2006 introduction of varenicline, a new prescription smoking-cessation aid, has had no significant impact on the rate at which Americans age 18 and older successfully quit smoking, according to a study led by researchers at UCSD School of Medicine. The findings, published online August 17 in “Tobacco Control,” suggest that the primary effect of varenicline, marketed as Chantix, has been to displace the use of older tobacco addiction therapies, such as nicotine patches and a popular antidepressant. Moreover, in this population analysis, researchers said varenicline’s enhanced effectiveness in helping smokers quit, compared with other cessation aides, appeared to be short-lived, lasting for three months, after which time varenicline users no longer had higher rates of success. According to the Centers for Disease Control, almost 20 percent of American adults 18 years or older are cigarette smokers. If smoking continues at the current rate among U.S. youth, one in every 13 persons younger than 18 is projected to die prematurely of a smoking-related illness. Globally, tobacco use is estimated to cause nearly 6 million deaths annually. For the study, School of Medicine researchers analyzed two U.S. Census Bureau surveys of smokers aged 18 and older, conducted in 2003 and 2010-11, before and after varenicline became commercially available. Based on responses from more than 39,000 smokers, overall use of pharmacotherapy increased from 28.7 percent of smokers trying to quit in 2003 to 31.1 percent in 2010-11, representing a 2.4 percent increase. This slight increase in the use of cessation aides, however, did not translate into more smokers breaking the habit. In 2003, approximately 4.5 percent of smokers reported successfully quitting for at least a year, compared with 4.7 percent in 2010-11. The study was funded in part by the National Cancer Institute under the State and Community Tobacco Control Initiative.