Clinical trial NCT03880838: Evaluation of a Letter Intervention Promoting a Plant-based Diet
Official title: Evaluation of a Letter Intervention Among At-risk Adults Promoting a Plant-based Diet Using a Combination of Provider Testimonials, the Forks Over Knives Documentary, and Commitment- or Prevention-focused Behavioral Nudges
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Cardiovascular Diseases
Diabetes Mellitus
Obesity
Keywords: Plant-based diet
Behavioral nudge
Mail distribution
Randomized controlled trial
Insurance claims
Chronic disease
Letter-based intervention
Health behaviors
Prevention focus
Loss framing
Commitment
Provider testimonial
Lead sponsor: Geisinger Clinic
Sponsor class: OTHER
First posted: 2019-03-19
Enrollment: 11234
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: FACTORIAL
Intervention model description: One group of participants will not be contacted at all (n = 6200). One group will only received a letter promoting a plant-based diet (n = 2200). Twelve groups (n = 550 for each group) will receive the letter promoting a plant-based diet, along with the Forks Over Knives documentary. The documentary will be delivered through 3 different methods, and the accompanying letter will contain 4 different combinations of behavioral nudges.

* 1 primary control group (no contact)
* 1 group contacted by letter
* 3 groups (documentary distribution: online link, DVD, online link + DVD) x 4 groups (behavioral nudges in the letter: no nudge, commitment nudge, prevention nudge, commitment and prevention nudges)

Note: The control group size is an estimate of number of participants who match the eligibility criteria but were not randomly assigned to an experimental group.
Primary purpose: SUPPORTIVE_CARE

Brief summary: The researchers' mission is to promote healthier eating behavior and to reduce costs associated with healthcare. The purpose of this study is to evaluate the effects of mailing randomly selected participants a letter promoting a plant-based diet. Depending on the experimental condition, participants may additionally receive a free documentary, Forks Over Knives, and they may also get letters which use commitment- or prevention-focused messages to encourage watching the documentary and changing their eating behavior. The researchers hypothesize that receiving the documentary will be associated with lower insurance claims and improved health outcomes one and two years later. The researchers also hypothesize that using either commitment- or prevention-focused messages will also contribute to lower insurance claims and improved health outcomes compared to experimental conditions where materials did not include these messages. This study will help the researchers design evidence-supported programs that can improve people's health.

Detailed description: Note that participant selection and assignment will be done at the level of the household, but analysis of outcomes will include individual-level analysis. This analytic decision was made because the researchers assume that the intervention may potentially affect other members of the household. While one person in a household will be selected for matching the eligibility criteria, the mailed materials will be addressed to all adult members of the household (defined as adults 18+ who are the spouse or child of the selected member) who are members of the Geisinger Health Plan. Outcome data will be pulled from all adult members of the household who have data through the Geisinger Health Plan.

The researchers will analyze the data using standard survey research analyses methods, including computing bivariate correlations, using general linear models, using non-parametric models for non-normally distributed insurance data, and entering variables as independent predictors in regression models to attempt to predict desired outcomes. The researchers will also use multilevel models to account for household- and individual-level data. The analysis of primary outcomes will focus on data one year after the intervention begins. Follow-up analysis on secondary outcomes will be conducted two years after the intervention begins. The researchers will conduct separate analyses of the selected participant (i.e., the individual who met the eligibility criteria) and other members of that participant's household. This will test whether there are any spillover effects of the intervention to other people in the household.

For clarity in this record, any discussion of sample size and participants refers to households, as this is the primary level for participant selection and assignment.

Eligibility criteria: Inclusion Criteria:

* Has two out of the three following conditions:

  * Body mass index over 30
  * Diagnosis of type 2 diabetes (specifically with at least one medication)
  * Diagnosis of cardiovascular disease
* Has health insurance through Geisinger Health Plan (is an active member with a full 12-month enrollment in the previous year) under one of the following categories:

  * Medicare with required primary care provider
  * Medicaid
  * Individual policy under the Affordable Care Act
* Has visited their primary care provider in the past 12 months

Exclusion Criteria:

* Is institutionalized
* Has active cancer, cirrhosis, renal failure, dementia, or active psychosis
* Is in the same household as another selected participant

Primary outcomes:
measure: Medical Cost in US Dollars From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Number of Visits From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Number of Prescriptions From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Number of Unique Prescribed Medication From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Body Mass Index From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Systolic Blood Pressure From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Diastolic Blood Pressure From One Year Before to One Year After Intervention
timeFrame: 2 years
Secondary outcomes:
measure: Triglyceride Levels From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Low-density Lipoprotein (LDL) Levels From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Five Years Before to Two Years After Intervention in Depressed Mood and Anhedonia as Assessed by the Patient Health Questionnaire-2 (PHQ-2) (Extended Time Frame)
timeFrame: 7 years
measure: Hemoglobin A1c (hbA1c) From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Low-density Lipoprotein/High-density Lipoprotein (LDL/HDL) Ratios From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: High-density Lipoprotein (HDL) Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Low-density Lipoprotein (LDL) Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Triglyceride Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Diastolic Blood Pressure From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Systolic Blood Pressure From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Body Mass Index From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Number of Unique Prescribed Medication From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Number of Prescriptions From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Number of Visits From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Medical Cost in US Dollars From Five Years Before to Two Years After Intervention (Extended Time Frame)
timeFrame: 7 years
measure: Values From One Year Before to One Year After Intervention of Depressed Mood and Anhedonia as Assessed by the Patient Health Questionnaire-2 (PHQ-2)
timeFrame: 2 years
measure: Hemoglobin A1c (hbA1c) From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: Low-density Lipoprotein/High-density Lipoprotein (LDL/HDL) Ratios From One Year Before to One Year After Intervention
timeFrame: 2 years
measure: High-density Lipoprotein (HDL) Levels From One Year Before to One Year After Intervention
timeFrame: 2 years
Other outcomes:
Locations:
city: Danville
country: United States
facility: Geisinger Health System
state: Pennsylvania
Study officials:
affiliation: Program Director
name: Amir Goren, PhD
role: PRINCIPAL_INVESTIGATOR
affiliation: Post-doctoral Fellow
name: Henri Carlo Y Santos, PhD
role: STUDY_DIRECTOR
affiliation: Professor
name: Christopher Chabris, PhD
role: STUDY_DIRECTOR
affiliation: Assistant Professor
name: Michelle N Meyer, PhD, JD
role: STUDY_DIRECTOR
affiliation: Vice President
name: Allison Hess, BS
role: STUDY_DIRECTOR
References:
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citation: Tversky A, Kahneman D. The framing of decisions and the psychology of choice. Science. 1981 Jan 30;211(4481):453-8. doi: 10.1126/science.7455683.