A Cochrane review [Abstract] 1 identified 136 trials; 133 with 64 640 participants contributing to the primary comparison between NRT and a placebo or non-NRT control group. The RR for abstinence for any form of NRT compared to control was 1.55 (95% CI 1.49 to 1.61). The RR for different forms of NRT were
for gum 1.49 (95% CI 1.40 to 1.60; 56 trials, n=22 581),
for patches 1.64 (95% CI 1.53 to 1.75; 51 trials, n=25 754) ,
for nasal spray 2.02 (95% CI 1.49 to 2.73; 4 trials, n=887),
for inhalator 1.90 (95% CI: 1.36 to 2.67; 4 trials, n=976),
for sublingual tablet/lozenge 1.52 (95% 1.32 to 1.74; 8 trials, n=4439), and
for oral spray 2.48 (95% CI 1.24 to 4.94; 1 trial) for oral spray. These RRs were largely independent of additional support provided, duration of treatment or the setting in which the NRT was offered. Eight weeks of patch therapy was as effective as longer courses. 4 mg gum was superior to 2 mg gum in highly dependent smokers (RR 1.85, 95% CI 1.36 to 2.50, 4 trials, n=618). Combining a nicotine patch with a rapid delivery form of NRT was more effective than a single type of NRT.
Another Cochrane review [Abstract] 2 included a network meta-analysis of 12 treatment-specific reviews (267 studies) involving 101804 participants. NRT was superior to placebo (odds ratios (OR) 1.84; 95% credible interval (CredI) 1.71 to 1.99, 119 trials). Head-to-head comparisons between bupropion and NRT showed equal efficacy (OR 0.99; 95% CredI 0.86 to 1.13, 9 trials). Varenicline was superior to single forms of NRT (OR 1.57; 95% CredI 1.29 to 1.91; indirect comparison). Varenicline was more effective than nicotine patch (OR 1.51; 95% CredI 1.22 to 1.87; indirect comparison), than nicotine gum (OR 1.72; 95% CredI 1.38 to 2.13; indirect comparison), and than 'other' NRT (inhaler, spray, tablets, lozenges; OR 1.42; 95% CredI 1.12 to 1.79; indirect comparison), but was not more effective than combination NRT (OR 1.06; 95% CredI 0.75 to 1.48; indirect comparison). Combination NRT also outperformed single formulations. The four categories of NRT performed similarly against each other, apart from 'other' NRT, which was marginally more effective than NRT gum (OR 1.21; 95% CredI 1.01 to 1.46). Mecamylamine in combination with NRT may increase the chances of quitting, but the current evidence is inconclusive.
Another Cochrane review [Abstract] 3 included 68 trials with a total of 43 327 subjects. Combination NRT (fast-acting form + patch) results in higher long-term quit rates than single form (RR 1.27, 95% CI 1.17 to 1.37; 16 trials, n=12 169, I ²=12%).
A review and meta-analysis 4 included 19488 smoking subjects. Combining a nicotine patch with other NRT products is more effective than use of a single NRT product. Combining drugs with different mechanisms of action, such as varenicline and NRT, has increased quit rates in some studies compared with use of a single product. The combination of a clinician's brief advice to quit and assistance to obtain tobacco cessation treatment is effective when routinely administered to tobacco users in virtually all health care settings.
Another Cochrane review [Abstract] 2 included a component network meta-analysis with 319 RCTs and 157 179 participants. Varenicline (OR 2.33, 95% CrI 2.02 to 2.68; 67 RCTs, n=16 430) and cytisine (OR 2.21, 95% CrI 1.66 to 2.97; 7 RCTs, n=3 848) were associated with higher quit rates than control. Combination NRT (patch and a fast-acting form of NRT (OR 1.93, 95% CrI 1.61 to 2.34), nicotine patch alone (OR 1.37, 95% CrI 1.20 to 1.56; 105 RCTs, 37 319), fast-acting NRT alone (OR 1.41, 95% CrI 1.29 to 1.55; 120 RCTs, 31 756) and bupropion (OR 1.43, 95% CrI 1.26 to 1.62; 71 RCTs, n=14 759) were more effective than control.
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