Nicotine replacement therapy may work fine in clinical trials, but not so much in the real world. That’s according to research published Monday in the journal Tobacco Control.

The study, by researchers at the Harvard School of Public Health and the University of Massachusetts, Boston, tracked 787 adults who had quit smoking.

Participants were interviewed three times, at two-year intervals; they were asked whether they still were abstaining from smoking, whether they used a nicotine replacement (either a prescription drug or an over-the-counter product such as nicotine-replacement gum, inhaler or patch), and whether they’d undergone counseling to help their cessation efforts.

The key findings: At each ­follow-up, nearly a third of those those who had initially reported they’d recently tried to quit reported that they had relapsed. The relapse rate was no different for those who hadn’t used nicotine replacements and those who had used it for more than six weeks, with or without counseling support. And there was no difference between heavy and light smokers’ success at quitting via the therapy.

Those findings differ from recent reviews of randomized controlled clinical trials , which found nicotine replacement therapy to be effective.

The authors note that a lot of federal money is being spent to provide nicotine replacement therapy, despite the fact that even as such products have become more widely available, earlier gains in reducing the number of smokers have stalled.

The authors suggest those earlier gains likely resulted from media campaigns, no-smoking policies, and initiatives to make tobacco more expensive.