Effects of interventions to combat tobacco addiction: Cochrane update of 2019 and 2020 reviews

Aims To summarize evidence on tobacco addiction interventions published by the Cochrane Tobacco Addiction Group (CTAG) from 2019 to 2020. Methods Narrative summary of all new and updated Cochrane Reviews published by CTAG in 2019 and 2020, outlining key results and promising avenues for future research. Results CTAG published six new reviews and updated 15 reviews. There is high-certainty evidence that combining fast-acting nicotine replacement therapy (NRT) with transdermal patches helped more people to quit than single-form NRT [risk ratio (RR) = 1.25, 95% confidence interval (CI) = 1.15-1.36, 14 studies, n = 11 356; I-2 = 4%] and moderate-certainty evidence that using NRT before quitting can increase quit rates more than using NRT from quit day onwards (RR = 1.25, 95% CI = 1.08-1.44, nine studies, n = 4395; I-2 = 0%). Reducing smoking in order to quit completely results in similar quit rates to abrupt quitting (RR = 1.01, 95% CI= 0.87-1.17; I-2 = 29%; 22 studies, n = 9219; moderate-certainty). Electronic cigarettes may help more people quit than NRT (RR = 1.53, 95% CI = 1.21-1.93; I-2 = 0%; four studies, n = 1924; moderate certainty), nicotine-free electronic cigarettes (RR = 1.94, 95% CI = 1.21-3.13; I-2 = 0%; five studies, n = 1447; moderate-certainty) and behavioural/no support (RR = 2.61, 95% CI = 1.44-4.74; I-2 = 0%; six studies, n = 2886; very low-certainty). Varenicline may help prevent relapse in abstainers (RR = 1.23, 95% CI = 1.08-1.41; I-2 = 82%; 11 studies, n = 1297; moderate-certainty), but behavioural support did not prevent relapse (RR = 0.98, 95% CI = 0.87-1.11; I-2 = 52%; 11 studies, n = 5523; moderate-certainty). Financial incentives increased quit rates in the general population (RR = 1.49, 95% CI = 1.28-1.73; I-2 = 33%; 30 studies, adjusted n = 20 097; high-certainty) and during pregnancy (RR = 2.38, 95% CI = 1.54-3.69; I-2 = 41%; nine studies, n = 2273; moderate-certainty). This overview also provides detail on a wider range of interventions. Conclusions There is high certainty that using nicotine replacement therapy from quit day increases smoking abstinence and no further research is required. Evidence is less certain that nicotine replacement increases abstinence when used in higher doses tailored to particular groups of smokers or use prior to quit day, and further research would be helpful. There is moderate-certainty evidence to support the use of e-cigarettes as cessation aids, but research on their role in preventing relapse would be particularly helpful.