Using e-cigarettes and other tobacco products to keep from relapsing to cigarettes doesn't appear to be effective, according to a new longitudinal study of nearly 13,000 smokers in the United States. "This is the first study to report on whether cigarette smokers can switch to e-cigarettes without relapsing to cigarette smoking," said study author John Pierce, [...] "Quitting is the most important thing a smoker can do to improve their health," he said in a statement attached to the study, "but the evidence indicates that switching to e-cigarettes made it less likely, not more likely, to stay off of cigarettes."