Impact of BC Farmers' Market Nutrition Coupon Program on Diet Quality and Psychosocial Well-being of Low-income Adults

NCT ID: NCT03952338

Last Updated: 2024-12-16

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 285 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2019-06-03
• Study Completion Date: 2020-03-31

Brief Summary

The British Columbia (BC) Farmers' Market Nutrition Coupon Program (FMNCP) provides low-income households with $21/week in coupons to purchase healthy foods at farmers' markets and supportive nutrition skill-building activities. This randomized controlled trial will assess the impact of the BC FMNCP on the overall diet quality (primary outcome), diet quality subscores, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition (secondary outcomes) and subjective social status (exploratory outcome) of low-income adults immediately post-intervention and 16 weeks post-intervention.

Detailed Description

Background: The British Columbia (BC) Farmers' Market Nutrition Coupon Program (FMNCP) is a healthy eating initiative funded by the BC Ministry of Health. The program provides low-income households with $21/week in coupons to purchase healthy foods at farmers' markets and supportive nutrition skill-building activities. It is not clear if the BC FMNCP is achieving its aims of improving the diet quality, well-being and health of low-income adults, as its outcomes have not been investigated, and studies of similar programs are limited by weak designs that cannot demonstrate causality. This randomized controlled trial will assess the impact of the FMNCP on the overall diet quality (primary outcome), diet quality subscores, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition (secondary outcomes) and subjective social status (exploratory outcome) of low-income adults immediately post-intervention and 16 weeks post-intervention. A qualitative investigation will also explore mechanisms of action and strategies to maximize positive program impacts.

Methods: Low-income adults (≥ 18 years) from up to 15 rural and urban communities will be randomized to a FMNCP intervention (n=132) or a no-intervention control group (n=132), with a 1:1 allocation ratio. An independent researcher from the Clinical Research Unit at the University of Calgary will generate a blocked randomization sequence that stratifies participants into blocks according to sex (male, female), geographic location (rural, urban), pregnancy (yes, no) and breastfeeding (yes, no). In the existing BC FMNCP, community partners distribute one to two sheets of coupons per week (each sheet contains $21 in coupons) to program participants for a total of 16 sheets. Coupons can be used over 16-20 weeks to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets. However, to allow sufficient time to recruit participants for this study, community partners will distribute 16 coupon sheets to the FMNCP group over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets). To ensure participants receive all 16 coupon sheets, community partners will provide two coupon sheets per household during the first 1-6 weeks of the intervention. Participants in the FMNCP group will also be invited to participate in nutrition skill-building activities (e.g., cooking classes). At baseline (0 weeks), immediately post-intervention (10-15 weeks) and 16 weeks post-intervention (26-31 weeks), participants will access a pilot-tested web-based platform to report sociodemographics, health-related variables, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition and subjective social status. Dietary intake will be assessed via two 24-hour dietary recalls at each time point using the Automated Self-Administered Dietary Assessment Tool for Canada (ASA24-Canada-2018). Diet quality scores will be calculated using the Healthy Eating Index-2015. In addition, immediately post-intervention only, participants will report whether they received FMNCP coupons and attended nutrition skill-building activities (to assess contamination of the control group), how often and how much of their own money was spent at farmers' markets during the intervention period and the types of foods purchased.

Data analysis: Descriptive analyses will be conducted to examine participant characteristics by group at each time point. Characteristics of study completers (i.e., provided data 16-weeks post-intervention) and non-completers will also be compared.

Analyses will be intention-to-treat, in which participants will be analysed within the groups to which they were randomized regardless of adherence (e.g., failure to redeem coupons) or dropout. The analyses will include all participants who provided data at baseline. Repeated measures mixed-effect regression will assess differences in mean HEI-2015 scores, HEI-2015 subscores, mental well-being, sense of community, and subjective social status between the FMNCP and control groups immediately post-intervention and 16-weeks post-intervention. Repeated measures multinomial logistic regression will be used to assess differences in the odds of experiencing household food insecurity and risk of malnutrition for the FMNCP group compared to the control group immediately post-intervention and 16-weeks post-intervention. Statistical models will include intervention group (FMNCP vs control), time from baseline, intervention-by-time interaction, blocking variables (i.e., sex, rural/urban, pregnancy, breastfeeding), baseline values of the outcome, and household size as fixed effects covariates. Participant-specific (i.e., repeated measures) variations in outcomes will be modeled using random effects. Models will also include covariates specific to each outcome to increase the precision of estimates (86). For the primary outcome of overall diet quality, models will include the following: children living in the home (yes, no), sex, age, BMI, marital status, race/ethnicity, perceived health, smoking, day of data collection, and educational level. Adjusted group differences (i.e., FMNCP group vs control group) in outcomes will be estimated using 95% confidence intervals and corresponding p-values.

Subgroup analyses will examine whether the impact of the intervention on primary and secondary outcomes differs according to age group or sex. Dose-response analyses will examine whether the impact of the BC FMNCP on overall diet quality depends on the number of coupons redeemed and the number of nutrition skill-building activities attended. Interactions will be retained in statistical models if p<0.10. Analyses will be conducted in Stata (v15.1, Stata Corp, TX, USA), with p<0.05 indicating statistically significant differences between groups. Data interpretation will jointly consider effect sizes, confidence intervals and statistical significance.

Expected outcomes: Findings will show whether and how a scalable population-level policy that links the agricultural and health sectors influences diet quality, psychosocial well-being and other outcomes among low-income adults. Study findings will inform program adjustments to improve participant outcomes. Other jurisdictions can use these data to determine whether and how to initiate similar programs.

Post-hoc analysis: In a post-hoc analysis, a random forest model will be used to explore heterogeneity of program effects on diet quality (total HEI-2015 scores) among different subgroups of FMNCP study participants. Candidate predictors entered into the algorithm will include all variables examined at baseline, including sociodemographic characteristics (e.g., age, sex, and income) and health-related variables (e.g., self-rated health and smoking). The outcome of the random forest analysis will be total HEI-2015 scores for both the FMNCP and control groups.

Conditions

Diet, Healthy; Health Risk Behaviors

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: DOUBLE

Study Groups

Nutrition Coupons

Participants in the FMNCP group will receive 16 coupon sheets (each sheet contains $21 in coupons) over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets) to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets. To ensure participants receive all 16 coupon sheets, community partners will provide two coupon sheets per household during the first 1-6 weeks of the intervention. Participants in the FMNCP group will also be invited to participate in nutrition skill-building activities (e.g., cooking classes) offered by community partners throughout the intervention period, however participation is not required (this is consistent with the existing FMNCP).

Group Type: EXPERIMENTAL

Food coupons

Intervention Type: OTHER

Participants will receive 16 coupon sheets (each sheet contains $21 in coupons) over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets) to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets.

Nutrition skill-building

Intervention Type: OTHER

Participants will be invited to participate in nutrition skill-building activities throughout the intervention period. To be consistent with the real-world program, the frequency and types of skill-building activities offered will vary by community partner, and participation is not required.

Control

No intervention provided. Participants will be eligible to participate in the BC Farmers' Market Nutrition Coupon Program during the next farmers' market season (i.e. one year following the current intervention).

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

Food coupons

Participants will receive 16 coupon sheets (each sheet contains $21 in coupons) over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets) to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets.

Intervention Type: OTHER

Nutrition skill-building

Participants will be invited to participate in nutrition skill-building activities throughout the intervention period. To be consistent with the real-world program, the frequency and types of skill-building activities offered will vary by community partner, and participation is not required.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Adults (age ≥ 18 years)
• Low-income as determined by community-specific thresholds (~$18,000/year annual household income before taxes)
• No expected change in household income prior to study completion (March 2020)
• 8 or fewer people living in the home (including the participant)
• No expected change in household composition prior to study completion (March 2020)
• Primary food shopper for the household
• Does not have self-reported dementia or Alzheimer's Disease
• Able to speak, read and write in English (or have someone who can assist them)
• No plans to move from principal residence prior to study completion (March 2020)
• Has not previously participated in the BC FMNCP

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Canadian Institutes of Health Research (CIHR)

OTHER_GOV

Sponsor Role: collaborator

British Columbia Farmers' Market Nutrition Coupon Program

OTHER

Sponsor Role: collaborator

University of Calgary

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Dana Olstad, PhD, RD

Role: PRINCIPAL_INVESTIGATOR

University of Calgary

Locations

Community Partners

Rural and Urban, British Columbia, Canada

Countries

Canada

References

Aktary ML, Dunn S, Sajobi T, O'Hara H, Leblanc P, McCormack GR, Caron-Roy S, Ball K, Lee YY, Nejatinamini S, Reimer RA, Pan B, Minaker LM, Raine KD, Godley J, Downs S, Nykiforuk CI, Olstad DL. Impact of a farmers' market healthy food subsidy on the diet quality of adults with low incomes in British Columbia, Canada: a pragmatic randomized controlled trial. Am J Clin Nutr. 2023 Apr;117(4):766-776. doi: 10.1016/j.ajcnut.2023.01.017. Epub 2023 Feb 1.

Reference Type: DERIVED

PMID: 36804420 (View on PubMed)

Aktary ML, Caron-Roy S, Sajobi T, O'Hara H, Leblanc P, Dunn S, McCormack GR, Timmins D, Ball K, Downs S, Minaker LM, Nykiforuk CI, Godley J, Milaney K, Lashewicz B, Fournier B, Elliott C, Raine KD, Prowse RJ, Olstad DL. Impact of a farmers' market nutrition coupon programme on diet quality and psychosocial well-being among low-income adults: protocol for a randomised controlled trial and a longitudinal qualitative investigation. BMJ Open. 2020 May 5;10(5):e035143. doi: 10.1136/bmjopen-2019-035143.

Reference Type: DERIVED

PMID: 32371514 (View on PubMed)

Provided Documents

Document Type: Study Protocol and Statistical Analysis Plan

View Document

Related Links

https://bcfarmersmarket.org/coupon-program/how-it-works/

BC Farmers' Market Nutrition Coupon Program

Other Identifiers

REB18-0508

Identifier Type: -

Identifier Source: org_study_id