Although smoking cessation products have been shown to be effective, it is unclear whether their benefits persist over time.
In Addiction (29 January 2018), researchers carried out a meta-analysis of 61 studies involving 27,647 participants who were randomly assigned to either an intervention group, which received smoking cessation medicines including bupropion, varenicline and nicotine replacement therapy, or to a control group, which did not receive active medicines
They found that, overall, less than 40% of those assigned to the intervention group were abstinent at three months, around a quarter were abstinent at six months and a fifth at 12 months. The net benefit of medication versus placebo declined significantly from 17.3% at three months to 8.2% at 12 months.
The researchers said the findings indicate that while the proportion of people who benefit from smoking cessation medications dwindles during the first year of use, this could still have a substantial impact on public health. However, there is a need for better smoking cessation and initiation strategies.
 Rosen L, Galili T, Kott J et al. Diminishing benefit of smoking cessation medications during the first year: a meta-analysis of randomized controlled trials. Addiction 2018. doi:10.1111/add.14134