This year Cochrane updated 5 reviews. It is important to note that all of these were based on those already motivated to quit and did not assess the ability of the intervention to prompt new quit attempts.
The 75 studies of print-based self help materials found that non-tailored materials had almost no benefit but tailored materials did (RR= 1.3) but these tailored benefits were also more intense. I would note that the Cochrane review on internet and social media treatments has not been recently updated.
The 14 studies of partner support examined 3 types of support –that from spouses, relatives/friends, and fellow smokers. None of these found support increased quit rates, because none actually increased support. This may be because relationships are very complex (note the large number of fiction and non-fiction books on this topic and the multi-session counseling needed in treatment). My pet hypothesis is that vulnerable smokers often know of few who have quit smoking and in this group of smokers buddy support is important (like in AA programs).
The 20 studies of competitions (e.g. Quit and Win) in this review included observational studies. Even so, no effect of these was found.
The 77 studies of relapse prevention again found that behavioral programs to prevent relapse have not been shown to work but continuing medications such as varenicline and NRT (RR = 1.2 for both) does seem to work. I think behavioral treatments are difficult because for most smokers it’s a “been there/done that” attitude and relapse often comes along so suddenly. My anecdotal observation is that easy availability of cigs is a major cause of relapse and should always be emphasized
The update of NRT included 136 studies (has any treatment been studied more thoroughly) and found no significant changes; i.e., slight differences in efficacy are not reliable differences. Although many have questioned whether NRT without advice is effective, the Cochrane reviews says it is. Separate reviews have examined pre-treatment, longer durations, higher doses of NRT, combined NRT. But the efficacy of NRT in pregnant women occurred in this review. The 6 studies found NRT increased abstinence at delivery but not at longer followup. The only side-effects that appeared to be due to nicotine were palpitations and chest pain, but these were very rare. Finally, I would note that the Cochrane Review “Pharmacological interventions for smoking cessation” clearly states that combined patch + gum/lozenge/inhaler is more effective than single treatment. In fact, I almost never use single treatment any more