The effect of introducing a financial incentive to promote application of fluoride varnish in dental practice in Scotland: a natural experiment

Wendy Gnich, Andrea Sherriff, Debbie Bonetti, David I. Conway, Lorna M. D. Macpherson

Financial incentives are often used to influence professional practice, yet the factors which influence their effectiveness and their behavioural mechanisms are not fully understood. In keeping with clinical guidelines, Childsmile (Scotland's oral health improvement programme) advocates twice yearly fluoride varnish application (FVA) for children in dental practice. To support implementation Childsmile offered dental practitioners a fee-per-item payment for varnishing 2-5-year-olds' teeth through a pilot. In October 2011 payment was extended to all dental practitioners. This paper compares FVA pre- and post-roll-out and explores the financial incentive's behavioural mechanisms. A natural experimental approach using a longitudinal cohort of dental practitioners (n = 1090) compared FVA pre- (time 1) and post- (time 2) financial incentive. Responses from practitioners who did not work in a Childsmile pilot practice when considering their 2-5-year-old patients (novel incentive group) were compared with all other responses (continuous incentive group). The Theoretical Domains Framework (TDF) was used to measure change in behavioural mechanisms associated with the incentive. Analysis of covariance was used to investigate FVA rates and associated behavioural mechanisms in the two groups. At time 2, 709 74%, of eligible responders, were followed up. In general, FVA rates increased over time for both groups; however, the novel incentive group experienced a greater increase (β [95% CI] = 0.82 [0.72 to 0.92]) than the continuous incentive group. Despite this, only 33% of practitioners reported 'always' varnishing increased risk 2-5-year-olds' teeth following introduction of the financial incentive, 19% for standard risk children. Domain scores at time 2 (adjusting for time 1) increased more for the novel incentive group (compared to the continuous incentive group) for five domains: knowledge, social/professional role and identity, beliefs about consequences, social influences and emotion. In this large, prospective, population-wide study, a financial incentive moderately increased FVA in dental practice. Novel longitudinal use of a validated theoretical framework to understand behavioural mechanisms suggested that financial incentives operate through complex inter-linked belief systems. While financial incentives are useful in narrowing the gap between clinical guidelines and FVA, multiple intervention approaches are required.