A Cochrane review [Abstract] 1 included 33 studies involving over 21 000 subjects. Incentives offered included cash payments or vouchers for goods and groceries, offered directly or collected and redeemable online. The risk ratio (RR) for quitting with incentives at longest follow-up (6 months or more) compared with controls was 1.49 (95% CI 1.28 to 1.73; 31 trials, n=20 097, I²=33%). The total financial amount of incentives varied considerably between trials, from zero (self-deposits), to a range of between USD 45 and USD 1185. There was no clear direction of effect between trials offering low or high total value of incentives, nor those encouraging redeemable self-deposits. Nine trials with usable data in pregnant smokers delivered an RR at longest follow-up (up to 24 weeks post-partum) of 2.38 (95% CI 1.54 to 3.69; n=2273, I²=41%, moderate-quality studies) in favour of incentives.
Another Cochrane review [Abstract] 2 included 81 studies. Provision of cost-free medications (RR 1.36, 95% CI 1.05 to 1.76; I² = 63%; 10 studies, n=7560) increased smoking abstinence at 6 months rates in primary care.
Comment: The quality of evidence is downgraded by limitations in study quality.
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