Trial Outcomes & Findings for Evaluation of a Letter Intervention Promoting a Plant-based Diet (NCT NCT03880838)

Results Overview

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.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

11234 participants

Primary outcome timeframe

2 years

Results posted on

2025-05-20

Participant Flow

The list of eligible participants was randomized before mail was sent (or not sent for no contact control group).

Participant milestones

Participant milestones
Measure	No Contact Control Participants were not contacted.	Letter Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges Participants were 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 Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges Participants were 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 Participants were 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 Commitment Nudge Participants were 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 Participants were 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 Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Overall Study STARTED	2434	2200	550	550	550	550	550	550	550	550	550	550	550	550
Overall Study COMPLETED	2434	2200	550	550	550	550	550	550	550	550	550	550	550	550
Overall Study NOT COMPLETED	0	0	0	0	0	0	0	0	0	0	0	0	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Data was not collected.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	No Contact Control n=2434 Participants Participants were not contacted.	Letter n=2200 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=550 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=550 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=550 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=550 Participants Participants were 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 n=550 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=550 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=550 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=550 Participants Participants were 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 n=550 Participants Participants were 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 Commitment Nudge n=550 Participants Participants were 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 n=550 Participants Participants were 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 n=550 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.	Total n=11234 Participants Total of all reporting groups
Age, Categorical <=18 years	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Data was not collected.
Age, Categorical Between 18 and 65 years	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Data was not collected.
Age, Categorical >=65 years	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Data was not collected.
Sex: Female, Male Female	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Data was not collected.
Sex: Female, Male Male	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Data was not collected.
Race and Ethnicity Not Collected	—	—	—	—	—	—	—	—	—	—	—	—	—	—	0 Participants Race and Ethnicity were not collected from any participant.
Region of Enrollment United States	2434 participants n=2434 Participants	2200 participants n=2200 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	550 participants n=550 Participants	11234 participants n=11234 Participants

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=1997 Participants Participants were not contacted.	Letter n=1849 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=434 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=466 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=459 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=447 Participants Participants were 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 n=453 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=453 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=458 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=458 Participants Participants were 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 n=472 Participants Participants were 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 Commitment Nudge n=454 Participants Participants were 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 n=451 Participants Participants were 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 n=457 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Medical Cost in US Dollars From One Year Before to One Year After Intervention 2019	6123.39 dollars Standard Deviation 9447.33	5863.82 dollars Standard Deviation 11818.81	5901.99 dollars Standard Deviation 11124.11	5630.26 dollars Standard Deviation 7461.85	6427.50 dollars Standard Deviation 9412.89	6343.24 dollars Standard Deviation 9206.43	6270.08 dollars Standard Deviation 9647.26	6336.36 dollars Standard Deviation 9452.46	6129.37 dollars Standard Deviation 10795.32	5542.03 dollars Standard Deviation 7632.87	6681.14 dollars Standard Deviation 10538.91	6850.98 dollars Standard Deviation 11812.93	6202.43 dollars Standard Deviation 8509.40	5305.93 dollars Standard Deviation 6743.15
Medical Cost in US Dollars From One Year Before to One Year After Intervention 2020	6101.54 dollars Standard Deviation 10076.51	6309.49 dollars Standard Deviation 13727.90	5754.70 dollars Standard Deviation 11157.93	5932.12 dollars Standard Deviation 8279.96	6078.06 dollars Standard Deviation 9847.06	7047.98 dollars Standard Deviation 14827.87	6284.85 dollars Standard Deviation 10203.78	6772.89 dollars Standard Deviation 10159.36	6709.80 dollars Standard Deviation 14548.68	5753.38 dollars Standard Deviation 7720.93	6723.81 dollars Standard Deviation 13785.71	6795.82 dollars Standard Deviation 12895.57	6275.88 dollars Standard Deviation 9067.47	5260.87 dollars Standard Deviation 6808.98

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=1997 Participants Participants were not contacted.	Letter n=1849 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=434 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=466 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=459 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=447 Participants Participants were 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 n=453 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=453 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=458 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=458 Participants Participants were 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 n=472 Participants Participants were 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 Commitment Nudge n=454 Participants Participants were 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 n=451 Participants Participants were 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 n=457 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Number of Visits From One Year Before to One Year After Intervention 2019	5.59 visits Standard Deviation 6.31	5.57 visits Standard Deviation 6.12	5.17 visits Standard Deviation 5.91	5.66 visits Standard Deviation 6.76	5.69 visits Standard Deviation 6.12	5.77 visits Standard Deviation 5.84	5.69 visits Standard Deviation 5.49	5.43 visits Standard Deviation 6.08	5.60 visits Standard Deviation 6.74	5.88 visits Standard Deviation 6.13	5.71 visits Standard Deviation 6.25	5.59 visits Standard Deviation 7.87	5.53 visits Standard Deviation 5.89	5.26 visits Standard Deviation 6.15
Number of Visits From One Year Before to One Year After Intervention 2020	4.77 visits Standard Deviation 5.65	4.80 visits Standard Deviation 5.56	4.26 visits Standard Deviation 5.30	4.88 visits Standard Deviation 5.78	4.89 visits Standard Deviation 5.52	5.13 visits Standard Deviation 5.36	4.82 visits Standard Deviation 5.29	4.51 visits Standard Deviation 5.31	4.49 visits Standard Deviation 5.49	5.27 visits Standard Deviation 5.80	5.15 visits Standard Deviation 5.85	4.69 visits Standard Deviation 6.24	4.63 visits Standard Deviation 5.18	4.34 visits Standard Deviation 5.06

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=1735 Participants Participants were not contacted.	Letter n=1580 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=381 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=403 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=391 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=404 Participants Participants were 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 n=403 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=395 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=399 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=411 Participants Participants were 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 n=413 Participants Participants were 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 Commitment Nudge n=395 Participants Participants were 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 n=382 Participants Participants were 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 n=399 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Number of Prescriptions From One Year Before to One Year After Intervention 2019	48.96 prescriptions Standard Deviation 49.89	48.02 prescriptions Standard Deviation 48.47	47.44 prescriptions Standard Deviation 49.70	50.85 prescriptions Standard Deviation 46.95	50.50 prescriptions Standard Deviation 46.08	49.66 prescriptions Standard Deviation 43.44	49.14 prescriptions Standard Deviation 54.80	52.71 prescriptions Standard Deviation 53.75	48.66 prescriptions Standard Deviation 43.52	49.34 prescriptions Standard Deviation 48.53	48.82 prescriptions Standard Deviation 51.30	50.02 prescriptions Standard Deviation 49.10	50.26 prescriptions Standard Deviation 49.83	43.81 prescriptions Standard Deviation 44.03
Number of Prescriptions From One Year Before to One Year After Intervention 2020	29.87 prescriptions Standard Deviation 47.45	26.82 prescriptions Standard Deviation 31.06	29.09 prescriptions Standard Deviation 62.85	29.86 prescriptions Standard Deviation 32.26	29.32 prescriptions Standard Deviation 33.00	30.35 prescriptions Standard Deviation 32.78	28.05 prescriptions Standard Deviation 32.78	30.24 prescriptions Standard Deviation 51.07	30.32 prescriptions Standard Deviation 35.34	31.70 prescriptions Standard Deviation 34.24	29.83 prescriptions Standard Deviation 36.16	27.83 prescriptions Standard Deviation 29.20	31.69 prescriptions Standard Deviation 36.72	27.30 prescriptions Standard Deviation 32.97

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=1735 Participants Participants were not contacted.	Letter n=1580 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=381 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=403 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=391 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=404 Participants Participants were 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 n=403 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=395 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=399 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=411 Participants Participants were 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 n=413 Participants Participants were 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 Commitment Nudge n=395 Participants Participants were 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 n=382 Participants Participants were 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 n=399 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Number of Unique Prescribed Medication From One Year Before to One Year After Intervention 2019	8.12 prescriptions Standard Deviation 6.08	8.15 prescriptions Standard Deviation 6.22	7.90 prescriptions Standard Deviation 6.08	8.50 prescriptions Standard Deviation 6.25	8.47 prescriptions Standard Deviation 6.29	8.48 prescriptions Standard Deviation 5.76	7.84 prescriptions Standard Deviation 6.18	8.77 prescriptions Standard Deviation 7.52	8.32 prescriptions Standard Deviation 6.11	8.39 prescriptions Standard Deviation 7.07	8.25 prescriptions Standard Deviation 6.17	8.45 prescriptions Standard Deviation 6.43	8.53 prescriptions Standard Deviation 6.63	7.50 prescriptions Standard Deviation 6.15
Number of Unique Prescribed Medication From One Year Before to One Year After Intervention 2020	5.92 prescriptions Standard Deviation 4.86	5.82 prescriptions Standard Deviation 5.05	5.80 prescriptions Standard Deviation 4.93	6.27 prescriptions Standard Deviation 5.28	6.00 prescriptions Standard Deviation 5.31	6.28 prescriptions Standard Deviation 5.36	5.70 prescriptions Standard Deviation 4.77	5.98 prescriptions Standard Deviation 6.18	6.13 prescriptions Standard Deviation 5.43	6.44 prescriptions Standard Deviation 5.99	6.28 prescriptions Standard Deviation 5.28	5.88 prescriptions Standard Deviation 4.68	6.39 prescriptions Standard Deviation 5.47	5.66 prescriptions Standard Deviation 4.96

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=2206 Participants Participants were not contacted.	Letter n=2022 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=500 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=506 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=505 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=497 Participants Participants were 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 n=503 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=510 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=499 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=506 Participants Participants were 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 n=516 Participants Participants were 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 Commitment Nudge n=512 Participants Participants were 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 n=498 Participants Participants were 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 n=509 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Body Mass Index From One Year Before to One Year After Intervention 2019	36.44 kg/m^2 Standard Deviation 7.35	36.48 kg/m^2 Standard Deviation 7.72	36.46 kg/m^2 Standard Deviation 7.53	36.20 kg/m^2 Standard Deviation 7.81	37.26 kg/m^2 Standard Deviation 7.59	36.58 kg/m^2 Standard Deviation 7.67	36.83 kg/m^2 Standard Deviation 8.76	36.56 kg/m^2 Standard Deviation 7.93	36.48 kg/m^2 Standard Deviation 7.33	37.00 kg/m^2 Standard Deviation 8.16	36.12 kg/m^2 Standard Deviation 7.67	36.83 kg/m^2 Standard Deviation 7.87	36.68 kg/m^2 Standard Deviation 7.80	35.76 kg/m^2 Standard Deviation 7.05
Body Mass Index From One Year Before to One Year After Intervention 2020	36.06 kg/m^2 Standard Deviation 7.44	36.05 kg/m^2 Standard Deviation 7.61	36.16 kg/m^2 Standard Deviation 7.67	36.18 kg/m^2 Standard Deviation 8.11	36.77 kg/m^2 Standard Deviation 7.72	36.19 kg/m^2 Standard Deviation 7.63	36.39 kg/m^2 Standard Deviation 8.42	35.96 kg/m^2 Standard Deviation 7.58	36.11 kg/m^2 Standard Deviation 7.72	36.77 kg/m^2 Standard Deviation 8.80	35.73 kg/m^2 Standard Deviation 7.66	36.42 kg/m^2 Standard Deviation 8.08	36.30 kg/m^2 Standard Deviation 7.92	35.30 kg/m^2 Standard Deviation 7.05

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=2199 Participants Participants were not contacted.	Letter n=2018 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=498 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=505 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=502 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=494 Participants Participants were 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 n=503 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=510 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=497 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=506 Participants Participants were 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 n=514 Participants Participants were 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 Commitment Nudge n=512 Participants Participants were 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 n=497 Participants Participants were 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 n=506 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Systolic Blood Pressure From One Year Before to One Year After Intervention 2019	130.00 mmHg Standard Deviation 17.57	129.88 mmHg Standard Deviation 17.19	130.47 mmHg Standard Deviation 17.97	131.4 mmHg Standard Deviation 16.59	130.72 mmHg Standard Deviation 17.33	129.27 mmHg Standard Deviation 17.18	129.88 mmHg Standard Deviation 16.97	127.98 mmHg Standard Deviation 18.50	129.19 mmHg Standard Deviation 17.03	131.46 mmHg Standard Deviation 16.85	130.41 mmHg Standard Deviation 17.32	129.59 mmHg Standard Deviation 17.10	130.39 mmHg Standard Deviation 17.17	129.29 mmHg Standard Deviation 17.90
Systolic Blood Pressure From One Year Before to One Year After Intervention 2020	129.50 mmHg Standard Deviation 17.94	129.97 mmHg Standard Deviation 18.31	130.57 mmHg Standard Deviation 17.00	130.26 mmHg Standard Deviation 19.08	129.91 mmHg Standard Deviation 17.03	129.73 mmHg Standard Deviation 18.17	129.53 mmHg Standard Deviation 17.33	127.58 mmHg Standard Deviation 18.13	129.37 mmHg Standard Deviation 17.20	131.79 mmHg Standard Deviation 17.33	129.63 mmHg Standard Deviation 17.55	129.25 mmHg Standard Deviation 18.01	129.90 mmHg Standard Deviation 17.29	129.70 mmHg Standard Deviation 17.67

PRIMARY outcome

Timeframe: 2 years

Population: Number of participants analyzed was based on the number of baseline (2019) records with no missing data for this outcome.

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.

Outcome measures

Outcome measures
Measure	No Contact Control n=2199 Participants Participants were not contacted.	Letter n=2018 Participants Participants were only contacted through a letter with a personal testimonial.	Link and no Nudge n=498 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and no nudges.	Link and Commitment Nudge n=505 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a commitment nudge.	Link and Prevention Nudge n=502 Participants Participants were sent the Forks Over Knives documentary online link and a letter with a personal testimonial and a prevention nudge.	Link and Both Nudges n=494 Participants Participants were 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 n=503 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and no behavioral nudges.	DVD and Commitment Nudge n=510 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a commitment nudge.	DVD and Prevention Nudge n=497 Participants Participants were sent the Forks Over Knives documentary DVD and a letter with a personal testimonial and a prevention nudge.	DVD and Both Nudges n=506 Participants Participants were 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 n=514 Participants Participants were 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 Commitment Nudge n=512 Participants Participants were 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 n=497 Participants Participants were 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 n=506 Participants Participants were sent the Forks Over Knives documentary online link and DVD and a letter with a personal testimonial and both commitment and prevention nudges.
Diastolic Blood Pressure From One Year Before to One Year After Intervention 2020	72.48 mmHg Standard Deviation 11.07	72.90 mmHg Standard Deviation 11.42	73.07 mmHg Standard Deviation 10.96	73.10 mmHg Standard Deviation 11.85	72.41 mmHg Standard Deviation 10.85	72.65 mmHg Standard Deviation 11.28	72.42 mmHg Standard Deviation 11.38	72.77 mmHg Standard Deviation 11.12	72.64 mmHg Standard Deviation 11.34	73.88 mmHg Standard Deviation 11.20	72.97 mmHg Standard Deviation 10.79	72.47 mmHg Standard Deviation 10.64	72.58 mmHg Standard Deviation 10.79	72.79 mmHg Standard Deviation 11.37
Diastolic Blood Pressure From One Year Before to One Year After Intervention 2019	72.91 mmHg Standard Deviation 10.99	72.79 mmHg Standard Deviation 10.91	72.95 mmHg Standard Deviation 10.89	73.48 mmHg Standard Deviation 10.09	72.93 mmHg Standard Deviation 10.90	72.27 mmHg Standard Deviation 10.40	72.57 mmHg Standard Deviation 10.37	72.44 mmHg Standard Deviation 11.13	72.80 mmHg Standard Deviation 10.51	73.44 mmHg Standard Deviation 10.78	73.26 mmHg Standard Deviation 10.41	73.21 mmHg Standard Deviation 10.51	73.11 mmHg Standard Deviation 10.79	73.04 mmHg Standard Deviation 10.68

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 7 years

Total number of primary care physician and specialist visits (sum) as reported by Geisinger Health Plan. Fewer visits is the desirable outcome.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 7 years

Total annual amount of medical and pharmacy costs (sum) as reported by Geisinger Health Plan. Lower costs is the desirable outcome.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: 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.