Evaluation of a Letter Intervention Promoting a Plant-based Diet

Not Applicable

Completed

Conditions: Obesity
Cardiovascular Diseases
Diabetes Mellitus

Interventions: Behavioral: Personal testimonial
Behavioral: Forks Over Knives Documentary
Behavioral: Prevention nudge
Behavioral: Commitment nudge

Registration Number: NCT03880838

Lead Sponsor: Geisinger Clinic

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 11234

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: FACTORIAL

Arm && Interventions

Group	Intervention	Description
Link and no nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.
Link and commitment nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.
Link and commitment nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.
Link and prevention nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.
Link and prevention nudge	Prevention nudge	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.
Letter	Personal testimonial	Participants are only contacted through a letter with a personal testimonial.
Link and commitment nudge	Commitment nudge	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.
DVD and no nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.
DVD and commitment nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.
Link and prevention nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.
Link and both nudges	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and both commitment and prevention nudges.
DVD and commitment nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.
DVD and commitment nudge	Commitment nudge	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.
Link and no nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.
Link and both nudges	Prevention nudge	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and both commitment and prevention nudges.
DVD and both nudges	Commitment nudge	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and both nudges	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and both commitment and prevention nudges.
DVD and no nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.
DVD and both nudges	Prevention nudge	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and commitment nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a commitment nudge.
Link and DVD and prevention nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a prevention nudge.
Link and DVD and prevention nudge	Prevention nudge	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a prevention nudge.
Link and both nudges	Commitment nudge	Participants are sent the Forks Over Knives documentary online link and a letter with a personal testimonial and both commitment and prevention nudges.
DVD and prevention nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.
DVD and both nudges	Personal testimonial	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and commitment nudge	Commitment nudge	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a commitment nudge.
Link and DVD and prevention nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a prevention nudge.
Link and DVD and both nudges	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and commitment nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and a commitment nudge.
DVD and prevention nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.
DVD and prevention nudge	Prevention nudge	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.
DVD and both nudges	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and no nudge	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and no behavioral nudges.
Link and DVD and no nudge	Forks Over Knives Documentary	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and no behavioral nudges.
Link and DVD and both nudges	Commitment nudge	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and both nudges	Personal testimonial	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Link and DVD and both nudges	Prevention nudge	Participants are sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.

Primary Outcome Measures

Name	Time	Method
Medical Cost in US Dollars From One Year Before to One Year After Intervention	2 years	Total annual amount of medical and pharmacy costs (sum) as reported by Geisinger Health Plan. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Lower costs is the desirable outcome.
Diastolic Blood Pressure From One Year Before to One Year After Intervention	2 years	Taken from annual checkup with primary care provider. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Systolic blood pressure that is 80 millimeters of mercury (mmHg) or less is the desirable outcome.
Number of Visits From One Year Before to One Year After Intervention	2 years	Total number of primary care physician and specialist visits (sum) as reported by Geisinger Health Plan. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Fewer visits is the desirable outcome.
Number of Prescriptions From One Year Before to One Year After Intervention	2 years	Total number of prescriptions (fills) as reported by Geisinger Health Plan. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Fewer prescriptions is the desirable outcome.
Number of Unique Prescribed Medication From One Year Before to One Year After Intervention	2 years	Total number of unique prescribed medication in the past year as reported by Geisinger Health Plan. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Less unique prescribed medication is the desirable outcome.
Body Mass Index From One Year Before to One Year After Intervention	2 years	Taken from annual checkup with primary care provider. Computed from height (in meters) and weight (in kilograms) data with the formula kilograms/meters\^2. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. A body mass index between the range of 18.5 to 25 is the desirable outcome.
Systolic Blood Pressure From One Year Before to One Year After Intervention	2 years	Taken from annual checkup with primary care provider. General linear models are used to model change between the data from the year before the intervention and the data from one year after intervention. Systolic blood pressure that is 120 millimeters of mercury (mmHg) or less is the desirable outcome.

Secondary Outcome Measures

Name	Time	Method
Triglyceride Levels From One Year Before to One Year After Intervention	2 years	One component of cholesterol, used if data is on health record. A triglyceride level of 150 milligrams per deciliter (mg/dl) or lower is the desirable outcome.
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)	7 years	Assesses depressed mood and anhedonia in the past two weeks; used if data is on health record. The sum of two items (each scored 0-3) is computed with a total score range of 0-6. A lower score is the desired outcome.
Low-density Lipoprotein (LDL) Levels From One Year Before to One Year After Intervention	2 years	One component of cholesterol, used if data is on health record. An LDL level of 100 milligrams per deciliter (mg/dl) or lower is the desirable outcome.
Hemoglobin A1c (hbA1c) From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Test for diabetes, used if data is on health record. Percentage score reflects blood-glucose levels. An hbA1c level of 5.7% and below is the desirable outcome.
High-density Lipoprotein (HDL) Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	One component of cholesterol, used if data is on health record. An HDL level of 60 milligrams per deciliter (mg/dl) or higher is the desirable outcome.
Triglyceride Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	One component of cholesterol, used if data is on health record. A triglyceride level of 150 milligrams per deciliter (mg/dl) or lower is the desirable outcome.
Diastolic Blood Pressure From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Taken from annual checkup with primary care provider. Systolic blood pressure that is 80 millimeters of mercury (mmHg) or less is the desirable outcome.
Number of Unique Prescribed Medication From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Total number of unique prescribed medication in the past year as reported by Geisinger Health Plan. Less unique prescribed medication is the desirable outcome.
Medical Cost in US Dollars From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Total annual amount of medical and pharmacy costs (sum) as reported by Geisinger Health Plan. Lower costs is the desirable outcome.
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)	2 years	Although originally listed as secondary, this outcome measure was intended to be exploratory. Due to the largely null pattern of results on the primary outcomes, it was decided to forgo additional analysis at this time.
Hemoglobin A1c (hbA1c) From One Year Before to One Year After Intervention	2 years	Test for diabetes, used if data is on health record. Percentage score reflects blood-glucose levels. An hbA1c level of 5.7% or lower is the desirable outcome.
Low-density Lipoprotein/High-density Lipoprotein (LDL/HDL) Ratios From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Computed as the ratio of LDL/HDL. An LDL/HDL ratio of 3 or less for men and 2.5 or less for women is the desirable outcome.
Low-density Lipoprotein (LDL) Levels From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	One component of cholesterol, used if data is on health record. An LDL level of 100 milligrams per deciliter (mg/dl) or lower is the desirable outcome.
Body Mass Index From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Taken from annual checkup with primary care provider. Computed from height (in meters) and weight (in kilograms) data with the formula kilograms/meters\^2. A body mass index between the range of 18.5 to 25 is the desirable outcome.
Systolic Blood Pressure From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Taken from annual checkup with primary care provider. Systolic blood pressure that is 120 millimeters of mercury (mmHg) or less is the desirable outcome.
Number of Prescriptions From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Total number of prescriptions (standard unit is prescription per number of days supplied) as reported by Geisinger Health Plan. Fewer prescriptions is the desirable outcome.
Number of Visits From Five Years Before to Two Years After Intervention (Extended Time Frame)	7 years	Total number of primary care physician and specialist visits (sum) as reported by Geisinger Health Plan. Fewer visits is the desirable outcome.
Low-density Lipoprotein/High-density Lipoprotein (LDL/HDL) Ratios From One Year Before to One Year After Intervention	2 years	Computed as the ratio of LDL/HDL. An LDL/HDL ratio of 3 or less for men and 2.5 or less for women is the desirable outcome.
High-density Lipoprotein (HDL) Levels From One Year Before to One Year After Intervention	2 years	One component of cholesterol, used if data is on health record. An HDL level of 60 milligrams per deciliter (mg/dl) or higher is the desirable outcome.