Financial incentives for maintaining postpartum smoking abstinence: 3-4-year follow-up of the Financial Incentives for Prevention of Postpartum Return to Smoking (FIPPS) randomised controlled trial.

Abstract

We followed up a financial incentives trial aimed at maintaining smoking cessation postpartum, which showed some positive effects at one year, to assess sustained abstinence at 3-4 years postpartum. Secondary analysis of longer-term outcomes of a pragmatic, multi-centre, three-arm randomized controlled trial, recruiting 462 postpartum women in England, aged ≥16 years, having stopped smoking during pregnancy with financial incentives, validated as abstinent at end of pregnancy or early postpartum. (1) usual care (UC); (2) UC plus up to £60 of voucher incentives offered to participants and £60 offered to significant-other supporters, over 3 months postpartum, contingent upon validated abstinence ('3-months incentives'); or (3) UC plus '3-months incentives' plus £180 of vouchers offered to participants over 9 months postpartum (leading to a maximum of £240 of incentives for participants, plus £60 for significant others), contingent upon validated abstinence ('12-months incentives'). Participants who did not achieve sustained abstinence at one year were included as non-abstainers but were not followed-up. Primary outcome: biochemically validated abstinence at 3-4 years postpartum. Statistical significance was set at P < 0.017 to account for multiple comparisons. Among the full trial sample, 63% (289/462) of participants had self-reported smoking status at 3-4 years postpartum; 19% (88/462) reported as abstinent, of whom 64% (56/88) underwent biochemical validation with none misclassified. Primary outcome abstinence was 16.4% (26/159) for 12-months incentives, 12.3% (19/154) for 3-months incentives and 7.4% (11/149) for UC. Adjusted odds ratios (OR) (95% confidence interval) for 12-months vs. UC: OR 2.51 (1.18-5.31), P = 0.016, and for 3-months vs. UC: 1.81 (0.83-3.98), P = 0.138. In a fully adjusted model, the difference between 12-month incentives and UC was no longer statistically significant: OR 2.44 (1.11-5.36), P = 0.027, using the Bonferroni correction (P < 0.017). Bayes factors indicated that for 12-months vs. UC there was good evidence for the alternative hypothesis and for 3-months vs. UC there was inconclusive evidence for the null or alternative hypothesis. Up to £300 of voucher incentives offered over 12 months postpartum may be effective for maintaining smoking abstinence at 3-4 years postpartum compared with usual care. Up to £120 of incentives over 3 months postpartum does not appear to be beneficial compared with usual care.