The impact of financial incentives on participants’ food purchasing patterns in a supermarket-based randomized controlled trial

International Journal of Behavioral Nutrition and Physical Activity

Short Paper

Ha ND Le¹  Sarah A McNaughton²  Gavin Abbott²  Kylie Ball²  David A Crawford²  Dana Lee Olstad³  Cliona Ni Mhurchu⁴  Christina Pollard⁵ 

[1] Deakin University, Geelong, Australia, Deakin Health Economics, 221 Burwood Highway, 3125, Burwood, Victoria, Australia;Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Locked Bag 20000, 3220, Geelong, Australia;Department of Community Health Sciences, University of Calgary, 3280 Hospital Drive NW, T2N 4Z6, Calgary, Canada;National Institute for Health Innovation, School of Population Health, The University of Auckland, Private Bag 92019, Auckland Mail Centre, 1142, Auckland, New Zealand;School of Public Health, Faculty of Sciences, Curtin University, GPO Box U1987, 6845, Perth, Western Australia, Australia;

关键词: Supermarket;    Food purchasing;    Fruits and vegetables;    Price reductions;    Randomized controlled trial;   

DOI  :  10.1186/s12966-017-0573-0

 received in 2017-03-16, accepted in 2017-08-17,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundThe impacts of supermarket-based nutrition promotion interventions might be overestimated if participants shift their proportionate food purchasing away from their usual stores. This study quantified whether participants who received price discounts on fruits and vegetables (FV) in the Supermarket Healthy Eating for Life (SHELf) randomized controlled trial (RCT) shifted their FV purchasing into study supermarkets during the intervention period.MethodsParticipants were 642 females randomly assigned to a 1) skill-building (n = 160), 2) price reduction (n = 161), 3) combined skill-building and price reduction (n = 160), or 4) control (n = 161) group. Participants self-reported the proportion of FV purchased in study supermarkets at baseline, 3- and 6-months post-intervention. Fisher’s exact and χ2 tests assessed differences among groups in the proportion of FV purchased in study supermarkets at each time point. Multinomial logistic regression assessed differences among groups in the change in proportionate FV purchasing over time.ResultsPost-intervention, 49% of participants purchased ≥50% of their FV in study supermarkets. Compared to all other groups, the price reduction group was approximately twice as likely (RRR: 1.8-2.2) to have increased proportionate purchasing of FV in study supermarkets from baseline to post-intervention (p< 0.05).ConclusionsParticipants who received price reductions on FV were approximately twice as likely to shift their FV purchasing from other stores into study supermarkets during the intervention period. Unless food purchasing data are available for all sources, differential changes in purchasing patterns can make it difficult to discern the true impacts of nutrition interventions.Trial registrationThe SHELf trial is registered with Current Controlled Trials Registration ISRCTN39432901, Registered 30 June 2010, Retrospectively registered (http://www.isrctn.com/ISRCTN39432901).

【 授权许可】

CC BY   
© The Author(s). 2017