Evaluating the effect of individually-targeted food incentives on grocery purchases: The smart cart study protocol for a randomized controlled cross-over trial.

Background/aims: Health stakeholders are interested in the promise of healthy food incentives to improve dietary quality. The Smart Cart Study tested whether targeting healthful food incentives based on customer preferences and purchase history was effective for improving grocery purchase quality.

Design: Randomized controlled crossover design of 224 adults who shopped at an independent supermarket for ≥50% of their groceries, participated in the store's loyalty program, and completed validated diet and sociodemographic/behavioral questionnaires. Participants were randomized using 1:1 blocked randomization; all participants received a 5% discount on their purchases with their loyalty card. For the first 13-weeks, the intervention group received individually-targeted weekly coupons (valued up to $10) with brief nutrition education to improve grocery purchase quality. The study team developed healthy food coupons, and the study algorithm allocated targeted coupons to participants' loyalty cards using purchase history, dietary preferences/allergies, and baseline diet quality. Control participants received weekly untargeted nutrition education and occasional generic coupons. Following a 2-4 week washout period, the two groups crossed over. The primary study outcomes were purchases of targeted products and grocery purchase quality measured using the validated Grocery Purchase Quality Index-2016; the study was powered to detect a minimum 3% difference in purchase quality.

Conclusions: The Smart Cart Study tested a novel application of automated individually-targeted marketing using customer purchase history, dietary quality, and preferences to identify and deliver targeted incentives to improve grocery purchase quality. Future research could scale this program through collaboration between multiple stakeholders, including supermarkets, workplace wellness initiatives and insurance companies.