ObesitywagesNCT03962712
A Natural Experiment Evaluating the Effect of a Minimum Wage Increase on Obesity and Diet-related Outcomes
An observational study of Obesity and Nutrition Poor, run by University of Connecticut at 1 site in United States.
Trial summary
To evaluate the effect of the Minneapolis minimum wage ordinance on change in body mass index among low-wage workers. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Obesity, Nutrition Poor
- What is being tested?
- Increase Minimum Wage to $15-an-hour and No Increase in Minimum Wage
- How many people
- 974 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Feb 2018to 20 Mar 2023
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Low wage workers living in Minneapolis, MN or Raleigh, NC.
Who may be able to join
- Age 18 or older.
- Plan to serve in the workforce for at least 5 years
- Have an address and phone number where they can receive mail and phone calls (though they do not necessarily need to own a phone or have a permanent home)
- Speak English or Spanish well enough to complete the survey
- Either A OR B must be true:
- A: Work at a wage of $11.50 an hour for at least an average of 10 hours a week, with at least 2 of those hours at a job in Minneapolis B: Be currently unemployed, but worked at a wage of $11.50 an hour or less for at least an average of 10 hours a week in the last 6 months AND be currently looking for working in Minneapolis
Who cannot join
- Federal or state workers
- Full-time students
- Plan to retire or move more than 100 miles away in the next 5 years
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Minnesota
Minneapolis, Minnesota, 55414
About this study
To evaluate the effect of the Minneapolis minimum wage ordinance on change in body mass index among low-wage workers.
Read the detailed description
On June 30 2017, Minneapolis became the 40th local jurisdiction to set the minimum wage above the state level, following a succession of other cities and counties across the U.S that have passed similar ordinances since 2012. The city of Minneapolis will incrementally increase the minimum wage from $9.50 to $15 by July 1, 2022 for all businesses with greater than 100 employees; minimum wage in smaller businesses will increase from $7.75 to $13.50 during this same time period. The ordinance specifically states that its purpose is to "maintain worker's health, efficacy, and general well-being." A report by members of the study team at the Humphrey School of Public Affairs at University of Minnesota estimates that the ordinance would increase wages by an average of 22% for the 71,000 city workers making minimum wage or just above minimum wage; moreover, it would affect 41% of non-Hispanic black workers and 54% of Hispanic workers, compared with 17% of white workers. The report also projects a post-policy decrease in food insecurity of 3.8 percentage points and an increase in food expenditures of $26 per week among affected workers.
The available evidence suggests that minimum wage laws may be associated with a range of health outcomes, including obesity. Obesity affects 36.5% of Americans, and is disproportionately high among non-Hispanic blacks and Hispanics. A study by Meltzer and Chen (2009) estimated that 10% of the increase in body mass in the U.S. since 1970 can be explained through the diminished value of minimum wages by inflation, while Kim \& Leigh (2010) used instrumental variables to demonstrate that low wages increase the risk of obesity. Mechanisms through which increasing the minimum wage could reduce obesity include improving food security and reducing cost constraints for purchasing healthier foods. However, existing studies linking wages and weight have design weaknesses that limit causal inference and the ability to identify causal mechanisms. A prospective study with a strong counterfactual condition is needed to test whether and how an increase in minimum wage results in improved obesity-related outcomes among low-wage workers.
Throughout the 4.5-year implementation period of the Minneapolis minimum wage ordinance (January 1, 2018-July 1, 2022), the team will follow a cohort of low-wage workers in a natural experiment, using a difference-in-difference design to compare a panel of obesity-related measures among low-wage workers (those earning ≤$10 an hour at baseline) in Minneapolis (n = 400) with low-wage workers in a comparison city with no minimum wage increase (Raleigh, North Carolina, n = 400).
- Conditions
- Obesity, Nutrition Poor
- Being tested
- Increase Minimum Wage to $15-an-hour, No Increase in Minimum Wage
- Keywords
- obesity, overweight, food insecurity, food assistance program, minimum wage
- Medical subject headings
- Obesity, Malnutrition, Overweight
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Increase Minimum Wage to $15-an-hourOther
Increase in minimum wage to $15-an-hour
No Increase in Minimum WageOther
No increase in minimum wage
| Study group | Role | What they receive |
|---|---|---|
| Low-Wage Workers from Minneapolis, MN | Low-wage workers from Minneapolis, MN, where the minimum wage will be increased to $15-an-hour over the study period. Receives: Other: Increase Minimum Wage to $15-an-hour | |
| Low-Wage Workers from Raleigh, NC | Low-wage workers from Raleigh, NC, where the minimum wage will not be significantly changed over the study period. Receives: Other: No Increase in Minimum Wage |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Body Mass Index
Body mass index (BMI) will be measured over 5 years among low-wage workers in Minneapolis compared to workers in a comparison (control) city, as assessed by objective annual height and weight measurements.
Measured: 5 years
Secondary outcomes (3)
Change Purchase of Healthier Foods
Change in purchasing of healthier foods (e.g. fruits and vegetables) and less healthy foods (e.g. sugar sweetened beverages) will be measured by 2 weeks of food purchase receipts, among a cohort of low-wage workers in Minneapolis compared to a control city.
Measured: 5 years
Change in Food Insecurity
Change in food insecurity will be measured by the U.S. Household Food Security Survey Module: Six-Item Short Form (from the Economic Research Service, USDA September 2012), among a cohort of low-wage workers in Minneapolis compared to a control city. Scores are calculated by simple addition for the 6 items. Scores range from 0 (high food security) to 6 (very low food security).
Measured: 5 years
Change in Food Assistance Program Participation
Change in participation in government-supported food assistance program (SNAP, WIC, FRPL) will be measured by self report among a cohort of low-wage workers in Minneapolis compared to a control city.
Measured: 5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 May 2019
- Study start1 Feb 2018
- Primary completion15 Feb 2023
- Study completion20 Mar 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 974 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Connecticut
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Caitlin Caspi, University of Connecticut
- Investigators
- Caitlin E Caspi, ScD, Principal investigator, University of Connecticut
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03962712
- Sponsor's protocol ID
- H20-0087
- Acronym
- wages
- Status last verified
- Sep 2023
- First submitted
- 21 May 2019
- Last updated
- 21 Sep 2023
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 21 Sep 2023. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Natural Experiment Evaluating the Effect of a Minimum Wage Increase on Obesity and Diet-related Outcomes
- ClinicalTrials.gov ID
- NCT03962712
- Acronym / sponsor ID
- wages / H20-0087
- Conditions
- Obesity, Nutrition Poor
- Keywords
- obesity, overweight, food insecurity, food assistance program, minimum wage
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 974 participants (actual)
- Lead sponsor
- University of ConnecticutUniversity, hospital or other
- Study start
- 1 Feb 2018 (actual)
- Primary completion
- 15 Feb 2023 (actual)
- Study completion
- 20 Mar 2023 (actual)
- First posted
- 24 May 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
To evaluate the effect of the Minneapolis minimum wage ordinance on change in body mass index among low-wage workers.
Detailed description
On June 30 2017, Minneapolis became the 40th local jurisdiction to set the minimum wage above the state level, following a succession of other cities and counties across the U.S that have passed similar ordinances since 2012. The city of Minneapolis will incrementally increase the minimum wage from $9.50 to $15 by July 1, 2022 for all businesses with greater than 100 employees; minimum wage in smaller businesses will increase from $7.75 to $13.50 during this same time period. The ordinance specifically states that its purpose is to "maintain worker's health, efficacy, and general well-being." A report by members of the study team at the Humphrey School of Public Affairs at University of Minnesota estimates that the ordinance would increase wages by an average of 22% for the 71,000 city workers making minimum wage or just above minimum wage; moreover, it would affect 41% of non-Hispanic black workers and 54% of Hispanic workers, compared with 17% of white workers. The report also projects a post-policy decrease in food insecurity of 3.8 percentage points and an increase in food expenditures of $26 per week among affected workers.
The available evidence suggests that minimum wage laws may be associated with a range of health outcomes, including obesity. Obesity affects 36.5% of Americans, and is disproportionately high among non-Hispanic blacks and Hispanics. A study by Meltzer and Chen (2009) estimated that 10% of the increase in body mass in the U.S. since 1970 can be explained through the diminished value of minimum wages by inflation, while Kim \& Leigh (2010) used instrumental variables to demonstrate that low wages increase the risk of obesity. Mechanisms through which increasing the minimum wage could reduce obesity include improving food security and reducing cost constraints for purchasing healthier foods. However, existing studies linking wages and weight have design weaknesses that limit causal inference and the ability to identify causal mechanisms. A prospective study with a strong counterfactual condition is needed to test whether and how an increase in minimum wage results in improved obesity-related outcomes among low-wage workers.
Throughout the 4.5-year implementation period of the Minneapolis minimum wage ordinance (January 1, 2018-July 1, 2022), the team will follow a cohort of low-wage workers in a natural experiment, using a difference-in-difference design to compare a panel of obesity-related measures among low-wage workers (those earning ≤$10 an hour at baseline) in Minneapolis (n = 400) with low-wage workers in a comparison city with no minimum wage increase (Raleigh, North Carolina, n = 400).
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Low-Wage Workers from Minneapolis, MN | – | Other: Increase Minimum Wage to $15-an-hourLow-wage workers from Minneapolis, MN, where the minimum wage will be increased to $15-an-hour over the study period. |
| Low-Wage Workers from Raleigh, NC | – | Other: No Increase in Minimum WageLow-wage workers from Raleigh, NC, where the minimum wage will not be significantly changed over the study period. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Low wage workers living in Minneapolis, MN or Raleigh, NC.
Key inclusion criteria (6 listed)
- Age 18 or older.
- Plan to serve in the workforce for at least 5 years
- Have an address and phone number where they can receive mail and phone calls (though they do not necessarily need to own a phone or have a permanent home)
- Speak English or Spanish well enough to complete the survey
- Either A OR B must be true:
Key exclusion criteria (3 listed)
- Federal or state workers
- Full-time students
- Plan to retire or move more than 100 miles away in the next 5 years
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Increase Minimum Wage to $15-an-hourIncrease in minimum wage to $15-an-hour | Other | Low-Wage Workers from Minneapolis, MN |
| No Increase in Minimum WageNo increase in minimum wage | Other | Low-Wage Workers from Raleigh, NC |
Primary outcome
Change in Body Mass Index
Time frame: 5 years
Body mass index (BMI) will be measured over 5 years among low-wage workers in Minneapolis compared to workers in a comparison (control) city, as assessed by objective annual height and weight measurements.
3 secondary outcomes
Change Purchase of Healthier Foods
Time frame: 5 years
Change in Food Insecurity
Time frame: 5 years
Change in Food Assistance Program Participation
Time frame: 5 years
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Sep 2023.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Caitlin E Caspi, ScD principal investigator
University of Connecticut
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity and Nutrition Poor, run by University of Connecticut at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 21 Sep 2023. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Body Mass Index (time frame: 5 years). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Sep 2023.