Clinical trial NCT05070442: Diet Improvement Through Normative Experimentation
Official title: Diet Improvement Through Normative Experimentation
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Diet Quality
Keywords: Nutri-Score labels
Social norms
Peer comparison
Financial incentives
Loss aversion
Online grocery shopping
Lead sponsor: Duke-NUS Graduate Medical School
Sponsor class: OTHER
First posted: 2021-10-07
Enrollment: 248
Sex: ALL
Minimum age (years): 21
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: HEALTH_SERVICES_RESEARCH

Brief summary: This study aims to use a three-arm randomized control trial (RCT) implemented in a fully functional experimental online grocery store, to explore the effects of two low-cost information and incentive-based strategies. These strategies comprise of injunctive norm-based messaging and the use of financial incentive leveraging on loss aversion to encourage the purchase of healthy foods. The investigators have set up a store wherein products may be purchased by participants and subsequently delivered to homes in some of the conditions. This increases the external validity of these interventions and enables investigators to establish greater confidence in their generalizability.

Detailed description: The Asia-Pacific is faced with an epidemic of rising rates of chronic disease. Poor diet quality is a demonstrated risk factor for non-communicable diseases. Excess intake of calories, saturated fat and sodium increases the risk of obesity, heart disease, diabetes, and other chronic conditions.

Behavioral economics has emerged as a promising strategy to increase the effectiveness of interventions aimed to address risk factors for non-communicable diseases (NCDs). Yet, there is a gap in knowledge concerning how norm-based messaging and peer influence interventions can be implemented to improve diet quality.

Using a three-arm randomized trial with a 3x3 crossover design, investigators aim to determine whether norm-based messaging and peer comparisons, with or without financial incentives, improve diet quality.

Each participant will be exposed to all of the following intervention arms in random order:

Arm 1: Control arm. Participants will experience an unmodified version of NUSMart which replicates the traditional shopping experience of online grocery stores.

Arm 2: Participants will experience a modified version of NUSMart with norm-based messaging and peer comparison features enabled. Nutri-Score labels will be enabled and displayed on all products within the store. A floating side panel will provide a visual indicator of the participants' average weighted Nutri-Score.

Arm 3: Same as Arm 2, except participants are notified of an additional $5 reward towards participation reimbursement. However, this additional $5 will be forfeited if the basket average weighted Nutri-Score falls below the average of participants' peers'. (Financial incentive leveraging on loss aversion).

Investigators hypothesize the following:

Primary hypothesis: Diet quality, as measured by mean Nutri-Score weighted by number of servings of all basket items, will be greatest when exposed to the intervention with norm-based messaging with incentive (Arm 3), followed by the intervention with norm-based messaging without the incentive (Arm 2), followed by Control (Arm 1).

Investigators will test this hypothesis in total, and separately for foods and beverages given Singapore's focus on reducing intake of sugar-sweetened beverages.

Eligibility criteria: Inclusion Criteria:

* Singapore resident
* Age 21 and above
* Must be the primary weekly grocery shopper in their household

Exclusion Criteria:

* Non-Singapore resident
* Non-primary grocery shopper in their household
* Less than 21 years old

Primary outcomes:
measure: Diet Quality
timeFrame: After completion of data collection, an average of about 5 months
Secondary outcomes:
measure: Average Nutri-Score
timeFrame: After completion of data collection, an average of about 5 months
measure: Average Calories
timeFrame: After completion of data collection, an average of about 5 months
measure: Average Sodium
timeFrame: After completion of data collection, an average of about 5 months
measure: Average Sugar
timeFrame: After completion of data collection, an average of about 5 months
measure: Average Fat
timeFrame: After completion of data collection, an average of about 5 months
measure: Average Saturated Fat
timeFrame: After completion of data collection, an average of about 5 months
Other outcomes:
Locations:
city: Singapore
country: Singapore
facility: Duke-NUS Graduate Medical School
Study officials:
affiliation: Duke-NUS Graduate Medical School
name: Eric A Finkelstein, PhD MHA
role: PRINCIPAL_INVESTIGATOR
References: