Effect of 3 months and 12 months of financial incentives on 12-month postpartum smoking cessation maintenance: a randomised controlled trial

Abstract

Background and aims Offering financial incentives is effective for smoking cessation during pregnancy. We tested the effectiveness of financial incentives for maintaining postpartum cessation, comparing 12-month and 3-month incentives with each other and with usual care (UC). Design, setting and participants This study was a pragmatic, multi-centre, three-arm randomized controlled trial involving four English, National Health Service, stop smoking services. A total of 462 postpartum women (aged ≥ 16 years) took part, who stopped smoking during pregnancy with financial incentives, validated as abstinent from smoking at end of pregnancy or early postpartum. Interventions Interventions comprised (i) UC; (ii) UC plus up to £60 of financial voucher incentives offered to participants and £60 offered to an optional significant-other supporter, over 3 months postpartum, contingent upon validated abstinence (‘3-month incentives’); or (iii) UC plus ‘3-month incentives’ plus £180 of vouchers offered to participants over 9 months postpartum, contingent upon abstinence (‘12-month incentives’). Measurements Primary outcome: biochemically validated abstinence at 1 year postpartum. To adjust for testing all comparisons between groups with equal precision, P < 0.017 was necessary for significance. Secondary outcomes: self-reported and validated abstinence at 3 months postpartum; self-reported abstinence at 1 year postpartum. Findings Primary outcome ascertainment: abstinence was 39.6% (63/159) 12 months incentives, 21.4% (33/154) 3 months incentives and 28.2% (42/149) UC. Adjusted odds ratios [95% confidence interval (CI)] = 12-month versus 3-month incentives OR = 2.41 (95% CI = 1.46−3.96), P = 0.001; 12 months versus UC 1.67 (1.04−2.70), P = 0.035; 3 months versus UC 0.69 (0.41−1.17), P = 0.174. Bayes factors indicated that for 12-month versus 3-month incentives and 12 months versus UC there was good evidence for the alternative hypothesis, and for 3 months versus UC there was good evidence for the null hypothesis. Conclusions This randomized controlled trial provides weak evidence that up to £300 of voucher incentives over 12 months is effective for maintaining smoking abstinence postpartum compared with usual care. There was good evidence that 12-month incentives are superior to those over only 3 months, for which there was no evidence of effectiveness relative to usual care.