Canadian researchers say that six smoking-cessation treatments all outperformed placebos, but that none achieved particularly impressive results in helping smokers achieve long-term abstinence.

Researchers found that while varenicline was twice as effective than bupropion, for example, "the number of patients who remained abstinent from smoking at follow-up was low."

The treatments included varenicline, a nicotine nasal spray, bupropion (Wellbutrin), nicotine patches, tablets and gum. Researchers from McGill University and the University of Montreal reviewed past studies involving 32,000 individuals.

The authors said more work needs to be done to match smokers to optimal cessation drugs and strategies.

The study was published in the July 15, 2008 issue of the Canadian Medical Association Journal.