Multiphase Evaluation of Healthier Choice Symbol (HCS) Logo (DIET)
Last registered on December 06, 2018

Pre-Trial

Trial Information
General Information
Title
Multiphase Evaluation of Healthier Choice Symbol (HCS) Logo (DIET)
RCT ID
AEARCTR-0002883
Initial registration date
July 09, 2018
Last updated
December 06, 2018 2:32 AM EST
Location(s)

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Primary Investigator
Affiliation
Duke-NUS Medical School
Other Primary Investigator(s)
Additional Trial Information
Status
In development
Start date
2019-01-07
End date
2019-03-31
Secondary IDs
Abstract
Poor diets are known risk factors for chronic diseases, and in recent years, food labelling has been increasingly sought-after as a cost-effective intervention to help stem the rising trend in chronic diseases.

In efforts to promote a healthy diet, the Singapore Health Promotion Board (HPB) supplements traditional nutrition labelling with the Healthier Choice Symbol (HCS), which identifies food items within a specific category of foods as healthier choices. The original logos were enhanced to include additional information focusing on particular macronutrients, taking one of two themes; it either indicates that a product contains more of a healthier ingredient, or less of a less healthy ingredient.

However, to date, no published studies have assessed the role of the original and enhanced HCS logos in influencing food choices. There is a lack of scientific evidence on the role of the existing symbols in assisting consumers make healthier food purchasing decisions. There are also concerns over the unintended consequences of health claims made based on a single aspect of nutrient content, without considering other aspects. That is the goal of this effort. Specifically, we propose to conduct the following:

Use a three arm randomized controlled trial (RCT) and an experimental fully functional web-based grocery store to assess the causal effect of the new HCS logos on measures of diet quality either alone, or in combination with a complementary front-of-package (FOP) label: Physical Activity Equivalents (PAEs), which provides information on how long one would need to engage in a certain activity (e.g., jogging) to burn off one serving of the product.

We hypothesize that the greatest reduction in calories per serving (primary outcome) will occur in the HCS plus PAEs arm, followed by HCS only, and no logo control arm.
External Link(s)
Registration Citation
Citation
Finkelstein, Eric. 2018. "Multiphase Evaluation of Healthier Choice Symbol (HCS) Logo (DIET)." AEA RCT Registry. December 06. https://www.socialscienceregistry.org/trials/2883/history/38363
Experimental Details
Interventions
Intervention(s)
This study relies on a fully functional and customizable web grocery store with over 4,000 products. For the Control condition, the participants will not be exposed to any logo when they shop. For Intervention 1 (HCS logos), the participant will see the Healthier Choice Symbol logo applied to select foods, as is currently occurring in stores in Singapore. For intervention 2 (HCS + Physical Activity Equivalents), the participant will see the HCS logos where applicable, and additional information graphically displaying Physical Activity Equivalents (PAEs) for all products.
Intervention Start Date
2019-01-07
Intervention End Date
2019-03-31
Primary Outcomes
Primary Outcomes (end points)
Calories per serving (kCal per serving) is the primary outcome measure.
Primary Outcomes (explanation)
Calories per serving (kCal per serving) is calculated by dividing the total number of calories purchased in the shopping trip by the total number of servings purchased.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes:
1. Calories per Shopping Trip (kCal)
2. Diet quality per shopping trip, as measured by the Grocery Purchase Quality Index-2016 (GPQI-2016).
3. Diet quality per shopping trip, as measured by Nutri-Score.
4. Whole Grains, Calcium, Trans Fat, Sugar, Sodium, and Saturated Fats per serving, as each is specified as separate claims above the original HCS Logos on labelled products.
5. Proportion of HCS labelled products purchased (or would have been if not in control arm).
6. Cost per calorie ($ per kcal)
Secondary Outcomes (explanation)
1. Calories per Shopping Trip Will be calculated as the sum of all purchased products’ total calories.
2. Diet quality per shopping trip, as measured by the Grocery Purchase Quality Index-2016 (GQPI-2016). The GPQI is based on USDA Food Plan expenditure shares and includes 10 food-based components of the HEI-2010, plus processed meats.
3. Diet quality per shopping trip, as measured by Nutri-Score. Nutri-Score is an individual dietary index based on the British Food Standard Agency Nutrient Profiling System.
4. Whole Grains, Calcium, Trans Fat, Sugar, Sodium, and Saturated Fats per serving, as each is specified as separate claims above the original HCS Logos on labelled products.
5. Proportion of HCS labelled products purchased (or would have been if not in control arm).
6. Cost per calorie ($ per kcal) will be calculated since labels may simultaneously influence diet quality, cost and purchase volume.
Experimental Design
Experimental Design
For this three-arm RCT, an experimental online grocery store will be used. NUSMart Online Grocery Store contains over 4,000 products commonly purchased in local supermarkets (food & beverages only). NUSMart food items are sorted into various categories, such as dairy products, carbonated soft drinks, fresh meats & seafood and snacks. Participants are able to add and remove products to and from their online grocery cart and review their cumulative total cart cost. The web-based grocery store was designed to mirror an actual web-based grocery store in look and feel. All products include pictures of the item, retail prices and product descriptions.

Participants will only be recruited if they are Singapore residents aged 21 years or older who are the primary grocery shoppers for the household. Although men are eligible to enroll, we anticipate that the overwhelming majority of subjects will be women.

This will be a crossover study design with all participants exposed once to 3 shopping conditions (1xControl, 1x Arm 2 and 1x Arm 3) in random order. The total study duration for each participant is 3 weeks, with each participant spending 1 week in each shopping condition.

The 3 arms are:
2. Arm 1: A control arm that mirrors a traditional web-grocery store with no HCS or other FOP labels.
3. Arm 2: Similar to Arm 1 except select foods will also be displayed with the new HCS logos, as would currently occur in stores in Singapore.
4. Arm 3: Similar to Arm 2 with additional information graphically displaying Physical Activity Equivalents (PAEs) for all products.

Over the course of the subsequent 3 weeks, participants will log into the NUSMart website once a week and purchase their weekly groceries. Each participant will therefore shop a total of 3 times during the study. This will include 1 shop within each shopping condition (control, Arm 2 and Arm 3). Participants will be informed that there will be up to a 50% chance of each purchase involving actual payment and delivery. All unpaid orders will be kept for research purposes only and they will not receive any groceries. All participants will purchase and receive at least 1 and up to 3 of their grocery orders. This ensures that purchases will be an accurate reflection of their actual shopping experience.

Since there are 3 shopping conditions and the specific weeks that the participant’s shopping trips will be pre-determined for purchase (but unknown to participants), each participant will be randomly assigned at baseline to 1 of 6 groups that vary the sequence of shopping conditions and which shops will result in an actual food delivery.

They will be expected to spend between SGD50 and SGD250. A minimum spend ensures that participants complete a typical weekly grocery order. A maximum spend is to make the study more manageable given foods will need to be reordered and delivered.

The grocery orders that participants purchase will be reordered by Duke-NUS on RedMart, a popular online grocery store in Singapore, and RedMart will deliver the grocery items directly to the participants’ households. The store was created using products currently available on the RedMart website to allow us to repurchase from a single location. At the end of the study participants who have completed all 3 shops as instructed will receive a Lazada e-Voucher worth $75 payment that can be redeemed against any products on Lazada.
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer program.
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
108 individuals. Each individual will shop 3 times, once for each arm.
Sample size: planned number of observations
108 x 3 = 324 observations.
Sample size (or number of clusters) by treatment arms
108 per arm.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Sample size is determined to detect a standardized effect size of 0.3 in the calories per serving of baskets among the study arms with 80% statistical power, and 5% (two-sided) level of significance, assuming each participant shops once during each intervention period and a correlation of 0.5 in purchases across three intervention periods. Accounting for an upper limit of 20% attrition rate based on prior similar studies, we estimate that the required sample size will be 108 participants for the study.
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
National University of Singapore-Institutional Review Board
IRB Approval Date
2018-12-05
IRB Approval Number
S-18-073