Multiphase Evaluation of Healthier Choice Symbol (HCS) Logo (DIET)

Last registered on July 10, 2018

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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

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published

July 10, 2018, 5:35 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Country

Singapore

Region

Primary Investigator

Name

Eric Finkelstein

Affiliation

Duke-NUS Medical School

Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status

In development

Start date

2018-07-30

End date

2019-02-28

Keywords

Education, Health

Additional Keywords

Nutrition, Groceries, Calories, Online, Obesity, Label, Labeling, Front-of-package label, Shopping, Diet, BMI, Logo, nutrition labeling

JEL code(s)

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 to 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. To address these concerns, we propose to conduct the following:

Use a four 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 one of two complementary front-of-package (FOP) labels: 1) Calories or 2) Physical Activity Equivalents (PAEs), where the latter provides a graphical display of 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 plus calories, 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. July 10. https://doi.org/10.1257/rct.2883-1.0

Former Citation

Finkelstein, Eric . 2018. "Multiphase Evaluation of Healthier Choice Symbol (HCS) Logo (DIET)." AEA RCT Registry. July 10. https://www.socialscienceregistry.org/trials/2883/history/31669

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Experimental Details

Interventions

Intervention(s)

This study relies on a fully functional and customizable web grocery store with over 3,500 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 + Calories per Serving), the participant will see the HCS logos where applicable, and additional information displaying calories per serving for all products. For intervention 3 (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

2018-07-30

Intervention End Date

2019-02-28

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 Nutrient Rich Foods Index/100kCal (NRF/100 kCal).
3. 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.
4. Proportion of HCS labelled products purchased (or would have been if not in control arm).
5. 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 Nutrient Rich Foods Index/100kCal (NRF/100 kCal). We propose to use the NRF9.3 model.
3. 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.
4. Proportion of HCS labelled products purchased (or would have been if not in control arm).
5. Cost per calorie ($ per kcal) will be calculated since labels may simultaneously influence diet quality, cost and purchase volume.

Experimental Design

For this four-arm RCT, an experimental online grocery store will be used. NUSMart Online Grocery Store contains over 3,500 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 aged 21 years or older, weekly food shoppers, who are the primary grocery shoppers for the household, and are existing registered RedMart customers. 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 4 shopping conditions (1xControl, 1x Arm 2, 1x Arm 3 and 1x Arm 4) in random order. The total study duration for each participant is 4 weeks, with each participant spending 1 week in each shopping condition.

The 4 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 displaying calories per serving for all products. These will be displayed next to the price in equal font size.
5. Arm 4: Similar to Arm 2 with additional information graphically displaying Physical Activity Equivalents (PAEs) for all products.
Over the course of the subsequent 4 weeks, participants will log into the NUSMart website once a week and purchase their weekly groceries. Each participant will therefore shop a total of 4 times during the study. This will include 1 shop within each shopping condition (control, Arm 2, Arm 3 and Arm 4). Participants will purchase and receive at least 1 and up to 4 of their grocery orders. This ensures that purchases will be an accurate reflection of their actual shopping experience.

Since there are 4 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 24 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 4 shops as instructed will receive a RedMart e-Voucher worth $75 payment that can be redeemed against any products on RedMart.

Experimental Design Details

Randomization Method

Randomization done in office by a computer program.

Randomization Unit

Individual

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

192 invididuals. Each individual will shop 4 times, once for each arm. Randomization will be done in (24) blocks of 8.

Sample size: planned number of observations

192 x 4 = 768 observations.

Sample size (or number of clusters) by treatment arms

48 per arm.

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

This will be a crossover study design with all participants exposed once to all 4 shopping conditions (1xControl, 1xIntervention 1 (I1), 1x Intervention 2(I2), 1x Intervention 3(I3)) . We have calculated the sample size of a 4 (interventions) x 4 (periods) cross-over design. Participants will be block-randomized into 1 of 24 allocation sequence possible, with a block size of 8. We have used the sample size calculator from Harvard (http://hedwig.mgh.harvard.edu/sample_size/js/js_crossover_quant.html) and applied the following options: - 0.017 of significance level to account for three comparisons - 0.9 power - 0.3 minimal detectable difference in (standardized) means and standard deviation of 1, which gives a relative effect size of 0.3 (small). - Selected standard deviation of the difference between the two values for the same patient as we will analyze a model in differences - 25% attrition Rounding up to the closest multiple of 24 to keep the design exactly balanced suggests that we need a sample size of 192, blocked into 8 groups of 24.

Supporting Documents and Materials

IRB