Study protocol of an economic evaluation embedded in the Midwives and Obstetricians Helping Mothers to Quit Smoking (MOHMQuit) trial

BACKGROUND: Tobacco smoking during pregnancy is the most important preventable risk factor for pregnancy complications and adverse birth outcomes and can have lifelong consequences for infants. Smoking during pregnancy is associated with higher healthcare costs related to birth complications and during childhood. Psychosocial interventions to support pregnant women to quit are effective, yet provision of smoking cessation support has been inconsistent. The Midwives and Obstetricians Helping Mothers to Quit Smoking (MOHMQuit) intervention provides systems change, and leadership and clinician elements, to support clinicians to help women stop smoking in pregnancy. There have been few long-term analyses conducted of the cost-effectiveness of smoking cessation interventions for pregnant women that target healthcare providers. This protocol describes the economic evaluation of the MOHMQuit trial, a pragmatic stepped-wedge cluster-randomised controlled implementation trial in nine public maternity services in New South Wales (NSW), Australia, to ascertain whether MOHMQuit is cost-effective in supporting clinicians to help women quit smoking in pregnancy compared to usual care. METHODS: Two primary analyses will be carried out comparing MOHMQuit with usual care from an Australian health care system perspective: i) a within-trial cost-effectiveness analysis with results presented as the incremental cost per additional quitter; and ii) a lifetime cost-utility analysis using a published probabilistic decision analytic Markov model with results presented as incremental cost per quality-adjusted life-year (QALY) gained for mother and child. Patient-level data on resource use and outcomes will be used in the within-trial analysis and extrapolated and supplemented with national population statistics and published data from the literature for the lifetime analysis. DISCUSSION: There is increasing demand for information on the cost-effectiveness of implementing healthcare interventions to provide policy makers with critical information for the best value for money within finite budgets. Economic evaluation of the MOHMQuit trial will provide essential, policy-relevant information for decision makers on the value of evidence-based implementation of support for healthcare providers delivering services for pregnant women. TRIAL REGISTRATIONS: ACTRN12622000167763, registered 2 February 2022.