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Health Information, Prioritisation and Dietary Choices: Evidence from a Randomised Controlled Trial
Last registered on June 12, 2016

Pre-Trial

Trial Information
General Information
Title
Health Information, Prioritisation and Dietary Choices: Evidence from a Randomised Controlled Trial
RCT ID
AEARCTR-0001189
Initial registration date
June 12, 2016
Last updated
June 12, 2016 12:21 PM EDT
Location(s)
Primary Investigator
Affiliation
University of Edinburgh
Other Primary Investigator(s)
PI Affiliation
University of Bath
PI Affiliation
University of Edinburgh
Additional Trial Information
Status
On going
Start date
2016-03-01
End date
2016-12-31
Secondary IDs
Abstract
This project will examine how (i) different types of health information, and (ii) time availability affect people’s dietary choices. The main motivation behind this study is the idea that people may have limited cognitive resources and would thus prioritise other issues or problems rather than their dietary or lifestyle choices, instead relying on heuristics and defaults when making such decisions. Therefore, under such circumstances the provision of public health information may have little impact on people's choices, particularly such information is perceived as being of limited relevance or salience. In order to tackle these issues, we propose a lab experiment where in the first instance, participants will be randomly assigned to one of three groups – no information (the control group), generic health information, and targeted health information. In the generic health treatment, subjects will be exposed to standard health information on heart disease and diabetes issued by organisations like the UK’s National Health Service and the British Heart Foundation. In the targeted information treatment, subjects will obtain personalised health information via a specialised computer-based tool that calculates the relative risk of contracting heart disease or diabetes as well as suggestions to reduce this risk (e.g. eat more fruit & vegetables). In the second part of the experiment subjects would be allocated a fixed budget in order to spend on various food and drink items available from a specially-designed online supermarket, containing a mixture of obesogenic and healthy food and drinks. It is at this stage that the second level of variation will be introduced since subjects (across all information groups) will be randomly-assigned into two further groups – a high-priority group and a low-priority group. The high-priority group will be allowed 10 minutes in order to make their dietary choices from the virtual supermarket, while the low-priority group will only be allowed 3 minutes to make their choices. We will then use the nutritional information from the chosen basket of food and drink in order to determine the impact of health information and time availability on individual food choices, controlling for a number of factors like prior health knowledge, prior health status (and knowledge of such status), dietary habits, socio-economic factors and demographic indicators. We will also conduct a follow-up session 3 months later in order to measure the long-term impact of information provision on people's food choices.
External Link(s)
Registration Citation
Citation
Belot, Michele, Jonathan James and Jonathan Spiteri. 2016. "Health Information, Prioritisation and Dietary Choices: Evidence from a Randomised Controlled Trial." AEA RCT Registry. June 12. https://doi.org/10.1257/rct.1189-1.0.
Former Citation
Belot, Michele et al. 2016. "Health Information, Prioritisation and Dietary Choices: Evidence from a Randomised Controlled Trial." AEA RCT Registry. June 12. https://www.socialscienceregistry.org/trials/1189/history/8771.
Experimental Details
Interventions
Intervention(s)
The aim of this study is to analyze dietary choices among low socioeconomic individuals within the context of bounded rationality. Specifically, we consider a model where agents have limited cognitive resources that need to be allocated among various decisions, including food or dietary choices. Evidence shows that low-income individuals have various concerns that take up a considerable proportion of their cognitive resources, like for example financial problems or job insecurity (Mani et al, 2013). The hypothesis is then that such individuals would have limited resources to allocate towards health-related decisions and dietary choices specifically, particularly since the health ramifications of dietary habits are only realized in the distant future, as opposed to the more pressing immediate worries cited earlier. Therefore, within this context an agent would optimally allocate cognitive resources by prioritizing some decisions and relying on heuristics or defaults for other less immediate concerns like food choices. This mechanism can also be used to explain why public health campaigns may have little impact on people’s behavior, since they may perceive such information as being of limited salience or relevance.

We propose a 3x2 experimental design. In a first instance, participants will be randomly assigned to one of three groups depending on the information they will receive about their health and the relationship between health and diet: (1) no information (the control group), (2) generic health information, and (3) targeted health information.

In the no information (control group) individuals will be given articles on architecture/automobiles to read. These are designed and have been pre-tested to be neutral with respect to both health and food choices. In the generic health treatment, subjects will be exposed to standard health information issued by organisations such as the UK's National Health Service and the British Heart Foundation. They will also be provided general suggestions on lifestyle changes that can reduce the risks, these will not be based on their responses to the survey questions. In the targeted information treatment, subjects will obtain personalised health information via a specialised computer-based tool that calculates the relative risk of contracting heart disease or diabetes as well as suggestions to reduce this risk (e.g. eat more fruit and vegetables).

In the second part of the experiment subjects will be allocated a fixed budget and will be asked to allocate that budget between various food and drink items available from a specially-designed choice tool that has around 100 different products priced at the market prices of a major UK supermarket. The choice tool offers a mixture healthy and unhealthy food and drinks. It is at this stage that the second level of variation will be introduced. Subjects (across all information groups) will be randomly-assigned into two further groups - a “high-priority” group and a “low-priority” group. The high-priority group will have a longer time period to make their dietary choices (to be pre-tested), while the low-priority group will only be allowed a short time period (to be pre-tested) to make their choices. Participants will be able to see the products and the prices, but no further information. That is, the only variation we introduce here is in the time participants have to ponder upon their dietary choices without giving them access to more or less information across treatments.

We will then use the nutritional information from the chosen basket of food and drink to determine the impact of health information and time availability on individual food choices, controlling for a number of factors like current state of hunger, prior health knowledge, prior health status (and knowledge of such status), current dietary habits, socio-economic factors and demographic indicators. We will also conduct a follow-up session 3 months later in order to measure the long-term impact of information provision on people's food choices.
Intervention Start Date
2016-06-13
Intervention End Date
2016-09-30
Primary Outcomes
Primary Outcomes (end points)
The outcome variables that will be used in this study are mainly related to the participants' food and drink choices as elicited via the choice tool. As stated earlier, this tool measures both the quantity and amount spent on each item as well as the nutritional content of these choices. Therefore, for the purposes of this study we are interested in the following outcomes:

1) Proportion of budget spent on healthy items;
2) Proportion of budget spent on fruit and vegetables;
3) Total nutrient content of the food/drink basket, where the nutrients considered are calories, carbohydrates, fats, saturated fats, sugar, salt, fibre and protein (a separate outcome will be calculated for each nutrient);
4) Average nutrient content per 100g of the food/drink basket (where a separate average will be computed for each nutrient).

In the follow-up session, we shall also be interested in looking at how people's daily dietary habits have changed as a result of our intervention. This data is obtained from our 24-hour dietary recall, namely INTAKE24, which is a computer-based system that prompts users to input all the food and drink items consumed over the last 24 hours. For the purposes of this study, we shall be interested in the following data as outcome variables:

1) Number of fruit and vegetables;
2) Total nutrient content of the participants' daily dietary intake, where the nutrients considered are calories, carbohydrates, fats, saturated fats, sugar, salt, fibre and protein (a separate total will be calculated for each nutrient).

Furthermore, we shall also be interested in any self-reported dietary or lifestyle changes that the participants will undertake in the 3 months after the initial intervention. The follow-up questionnaire contains two questions related to this matter. The first question states: ``Looking back over the last 3 months, have you made any changes to your diet or lifestyle habits?'', which elicits a simple `Yes' or `No'. The second question follows-up on this point: ``If yes, please indicate the change in your diet or lifestyle that you have undertaken from the list below'', which then lists the following options: ``Stop smoking, Do more exercise, Eat more fruit and vegetables, Eat less junk food and processed foods, Eat less sugar, Eat less red meat, Take vitamins and other supplements, Drink less alcohol''. Therefore, we can use this data to obtain two outcome variables:

1) A simple dummy variable indicating whether any changes have been made;
2) A series of eight dummy variables for each response.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Upon arriving at the BLUE lab, all participants will be asked to fill out an initial questionnaire which will include questions related to demographics, socio-economic background, education, employment status, as well as various questions related to their prior knowledge regarding health, nutrition and their own health status. Participants will also be asked to complete a short food frequency questionnaire (based on the National Cancer Institute's Dietary Screener Questionnaire) in order to obtain a measure of their typical eating habits.

Following this initial stage, we will then move on to the actual interventions.

Subjects will be randomly-assigned to one of six (6) groups upon registration:

1) Information Control/Low Priority
2) Information Control/High Priority
3) Generic Information/Low Priority
4) Generic Information/High Priority
5) Tailored Information/Low Priority
6) Tailored Information/High Priority

Information Intervention
The first intervention in our study is related to the provision of different types of health information our subjects. In particular, we are interested in understanding the impact of the provision of tailored versus generic health information on people's food choices. We shall have a control group (Information Control) who will be provided with non-health related news stories and articles to read, taken from local and international media outlets.


The tailored information treatment group will be provided with personalised health information via an adapted version of a computer-based assessment tool called `Your Disease Risk' (YDR), which was developed by Washington University in St. Louis and Harvard University. The algorithms developed for this tool are used to measure the risk of ever contracting a particular disease, relative to the average person of the same age and gender. We have adapted the algorithm for the Scottish population using data from the Scottish Health Survey. These calculations are done on the basis of a series of questions that respondents are asked to fill in, related to their medical history, their parents' medical history, dietary habits (e.g. consumption of fruit and vegetables per day) and lifestyle choices (e.g. smoking, exercise, average daily alcohol consumption). Once these questions are answered, the YDR tool provides a scale showing the respondent's relative risk of contracting a particular disease, which ranges from `Low' to `High' (e.g. `Very Much Below Average', `Average', `Much Above Average', etc.). The system also supplies tailored recommendations to respondents which would help them to lower their risk (e.g. `Eat more unsaturated fats', `Stop smoking'.). For the purposes of this study, we shall be focussing solely on two diseases, namely heart disease and diabetes. Note that the questions required as inputs for the YDR tool are already included in the initial questionnaire described earlier, and hence will be answered by all participants. However, the Tailored Information group will be the only subjects to receive the YDR risk and recommendations (other groups will not be aware of this treatment).

The generic information treatment group will answer the same series of questions that respondents are asked to fill in for the tailored information treatment. At the end of these series of questions individuals will be given the average risk of developing cardiovascular and diabetes. For example, they will be told 1.5 people out of 100 will develop heart disease in Scotland within 10 years. This risk will be calculated using the same data as the tailored treatment but just for the entire Scottish population and will not be specific to the individual. They will then be given a comprehensive list of lifestyle changes that can be done to reduce the risk. The design is set up to ensure maximum comparability across treatments as this will allow us to assess the marginal impact of tailored health information relative to generic information.

Time Intervention
The second intervention in our study is related to the time available for each participant to make their food choices. The idea behind this treatment is that people have limited cognitive resources that must be allocated across various competing concerns, meaning that matters related to nutrition and health may not be high on an individual's list of priorities. This is particularly true in the case of most foods high in fat and sugar since most unhealthy foods yield immediate benefits in terms of taste or gratification while healthier foods are typically associated with more long-term benefits that may at present seem remote or even unclear. The lack of health prioritisation may be more acute for people from a low income background since various studies (e.g. Mani et al, 2013) have shown that poverty-related concerns occupy a large portion of a low-income person's mental resources, leaving less room for focussing on other matters. Therefore in this study we are explicitly trying to test this idea by introducing exogenous variation in the amount of time available for subjects to make their dietary choices.

At the start of this intervention, all participants will be allocated a budget of £30 in order to spend on food and drink from a specially-designed choice tool that appears similar to an online supermarket developed specifically for this study using VBA. The choice tool contains a total of 100 food and drink items, and an equal mixture of both healthy and unhealthy items across various grocery categories like fruit and vegetables, meat, fish, confectionery, chilled meals and drinks. Apart from capturing the participants' food choices in terms of which items were actually selected, the system has been designed to calculate the nutritional value of each basket along several key nutrients, namely carbohydrates, saturated fats, salt content, sugar content, fibre and protein. These will serve as our key outcome variables when analysing the data. All prices used in the online supermarket reflect current market prices at the leading high street supermarkets in the UK, in order to make the food selection task more realistic. Subjects will be allowed to spend their budget on any of the items listed in the online supermarket, just as long as they do not exceed the £30 limit. The experimental variation is related to the time available to select their food and drink items. The High Priority group will be given a longer time period to make their choices (and will be required to stay for the entire duration), while the Low Priority group will be given a shorter time period. Both time periods will be pre-tested in BLUE before the start of the experiment. At the end of each session, 1 subject per session will be picked at random and his/her food basket will be delivered to his/her home address within one week.

Post-Treatment and Follow-up
At the end of the study, all participants will be asked to fill in a short questionnaire, which is primarily designed to elicit three key facts:

Whether the participants updated their beliefs regarding their own health status following the information treatment;
Whether the participants believe that the information provided was credible/trustworthy or not;
Whether the choice tool was easy to use and comparable to their typical supermarket shopping experience.

This concludes the main session of our study. In order to gauge the long-term impact of the health information intervention, we plan on running a follow-up session 3 months later (in September 2016). In this session, participants will be asked to complete a short questionnaire to elicit their updated beliefs regarding their health status and whether they have undertaken any dietary changes (particularly for those who received tailored health information), the food frequency questionnaire, a 24-hour dietary recall (using the INTAKE24 software developed specifically for the UK by Newcastle University), and will once again be allocated a £30 budget to spend using our choice tool. In this instance there will be no time restrictions on their food choices - all participants will have a maximum of 30 minutes to make their choices and will not be required to stay for the entire time period. We will record the amount of time they stay in the laboratory and spend on the task.
Experimental Design Details
Randomization Method
Randomisation done in office by a computer
Randomization Unit
Randomisation is done at the experimental session level (we have a total of 20 sessions).
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
300 participants
Sample size: planned number of observations
300 participants
Sample size (or number of clusters) by treatment arms
Information treatment:
Control Group: 90
Generic Info: 105
Tailored Info: 105

Time availability treatment:
Low Priority: 150
High Priority: 150
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
University of Edinburgh School of Economics Ethics Committee
IRB Approval Date
2016-05-10
IRB Approval Number
None
Analysis Plan

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Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is data collection complete?
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers