Effectiveness of a behavioral incentive scheme linked to goal achievement: study protocol for a randomized controlled trial

Study design

The study is a cluster RCT (Fig. 1) delivered within the context of the existing Go4Fun program with 10 week, 6 month,
and 12 month follow-up (n?=?40 sites, 570 participants), which compares the effectiveness of participation
in the standard Go4Fun program with an enhanced goal setting and structured incentive
scheme (intervention) versus participation in the existing Go4Fun program (control).
Individual randomization is not possible given the nature of the intervention, so
randomization by site will be conducted. Building on our existing research platform,
we propose a pragmatic and feasible trial to determine the effectiveness, acceptability,
and sustainability of the enhanced intervention at 6 and 12 months after the program.
The CONSORT statements for cluster RCTs 43] and for nonpharmacological interventions 44] will be followed.

Fig. 1. Behavioral incentive study schema. BMI, body mass index; QOL, quality of life

Eligibility/recruitment: Sites (namely programs where Go4Fun is delivered)

To be eligible to participate in the trial, sites must meet the following criteria:

1. Are delivering the standard Go4Fun program in 2015;

2. Show a 2014 attendance average of at least 10 children enrolled per program per
term; and

3. Are willing to participate in a trial and adhere to standardized procedures for
the duration of the trial.

For site recruitment, all NSW LHDs (where Go4Fun is delivered) were invited to participate,
40 programs agreed to participate, and ethical approval was secured from the relevant
LHDs. Based on prior process evaluation work 17] and from prior attendance records, the recruited sites are likely to enroll an average
of 12 to 15 children per site per term. Local program leaders will assess eligibility,
obtain informed consent, and conduct baseline study visits, and research assistants
will conduct the follow-up assessments. Previous RCTs conducted by the research team
have underscored the critical importance of site-based program leader involvement
and engagement to maximize downstream sustainability.

Eligibility/recruitment: Participants

To be eligible to participate in this trial, leaders were instructed that children
must meet the following criteria:

i. Aged 7 to 13 years;

ii. Have a body mass index??85th percentile for their age and sex (according to AIHW
classification of overweight/obesity in children) 19], 45];

iii. Be enrolled in and meet the general criteria to participate in the Go4Fun program
at one of the sites participating in this study, which includes having a parent or
adult carer able to accompany them to each session; and

iv. Parent/guardian provides written and informed consent.

Participant/child eligibility for the Go4Fun program is assessed at the time of referral/contact
with their LHD. No changes will be made to this standard program enrolment process.
Eligibility will be determined by the program leaders based on assessment of the above
criteria once the child attends the initial intake appointment, and written informed
consent will be sought prior to collection of baseline data.

Randomization

Eligible sites have been randomized to either deliver the intervention (standard Go4Fun
plus incentives) or control (standard Go4Fun) program for 10 weeks. Randomization
was conducted using a computer-generated sequence (1:1) managed by the research team
based at The George Institute and independent of the Department of Premier and Cabinet
NSW (DPC), any program leader or LHD. Clusters were stratified according to local
health district to ensure equal representation across groups within each LHD.

Development of incentive scheme and standardized program

In late 2014, an iterative process combining literature review, focus groups, and
consensus meetings took place with three aims: namely, to (i) identify the best possible
incentive scheme based on available literature, (ii) standardize the existing Go4Fun
attendance rewards system across all treatment and control sites, and (iii) develop
and agree on the goal setting scheme and incentive structure to be used for the intervention
group. Participants included representatives from authorship group, program leaders
representing all LHDs, DPC (the Government department responsible for delivery of
Government priorities in NSW, Australia), Better Health Company, and the NSW Office
of Preventive Health. In addition, investigators from DPC conducted six field research
visits (including interviews) to collect feedback and ideas from the Go4Fun leaders
about potential ways to enhance the goal setting process and practical considerations
regarding delivery and impact as well as post-program engagement opportunities. A
literature review demonstrated the importance of incentivizing behavior rather than
outcomes. This approach was confirmed by Go4Fun leaders during early fieldwork so
that, despite being a core part of the Go4Fun program, goal-setting structures could
be improved by making the goals specific, measureable, achievable, relevant, and timely
(SMART) 32]. This emphasized the importance of enhancing the goal-setting process, including
resetting/stretching them if they are achieved too easily in the program, as well
as linking goal achievement to incentives 32].

Preliminary work highlighted the need for a standardized reward system for the control
program, and “healthy,” positive, and low-cost incentives (for example, items that
encourage physical activity and nutrition) were needed for the intervention group.
It was also agreed that incentives should be of increasing value as they become harder
to achieve. Once consensus was reached regarding the control program and the incentive
scheme for the intervention, formal standard operating procedures were prepared and
circulated for revision and refinement until consensus was reached. This process was
important to facilitate engagement and satisfaction of site leaders and to minimize
potential variability between sites. Specific rewards and associated delivery structure
are outlined further in the “intervention” section of this proposal.

Control group

Sites randomly allocated to the control group will continue to deliver the standard
Go4Fun program. As described above, the standard program consists of weekly group
sessions (one per week) for 10 weeks during the school term. Exercise sessions involve
one hour of activities that progressively develop skills, strength, fitness, confidence
and self-esteem 17]. Nutrition sessions include healthy eating advice, food label reading and recipes
17]. Behavioral change sessions include goal setting, problem solving and role modelling
to influence habits and behavior around eating and exercise 17]. Through preliminary focus groups, consensus was reached to ensure the standardization
of Go4Fun between sites. In particular, when and how children receive reward “stickers”
was standardized throughout the control program. It was also agreed that children
would receive incentives such as water bottles (for attending one session), bouncy
balls (for attending three sessions), and skipping ropes (for attending 10 sessions)
based on their record of attendance.

Intervention group

Sites randomly allocated to the intervention arm will deliver the Go4Fun program with
the enhanced goal setting and structured incentive scheme developed during our preliminary
work. As described above, the standard program consists of weekly group sessions (one
per week) for 10 weeks during the school term. No sessions have been lengthened or
combined for the intervention sites. All children participating in the intervention
sites will receive the same information and participate in the same exercise and nutrition
sessions as the control group. They will also receive the same system of “reward stickers”
and standardized attendance rewards throughout the program. However, at intervention
sites, participating children will be eligible to participate in an enhanced goal-setting
component and receive incentives for reaching certain levels of goal attainment. That
is, for the intervention, participants will set SMART 32] behavioral goals and achieving these goals will result in the incentives being provided.
This emphasizes the importance of enhancing the goal-setting process, including resetting/stretching
them if they are achieved too easily in the program, as well as linking goal achievement
to incentives 32]. The incentives will only be received for the period of the 10-week program.

The goal setting component and incentive scheme was developed and agreed upon during
the preliminary work for this study with an overview of the goal setting enhancement
and incentives being as follows:

1.
Goal setting: At the third session in the program, the children and their parent/ guardian in the
intervention group are provided with an enhanced resource to guide them through jointly
setting an exercise and a nutrition goal (child and parent/guardian in collaboration).
Examples include ‘I will play soccer for 30 minutes on 3 days a week at the park with
dad’ and ‘I will try a new vegetable two times a week for dinner on Wednesday and
Sunday nights.’

2.
Goal attainment incentives: Children will receive milestone-based incentives for achieving their set goals. There
will be three levels as follows: (i) a vegetable slicer once two exercise and two
nutrition goals are achieved; (ii) a sports store voucher (value of $AUS10) once four
exercise and four nutrition goals are achieved, and (iii) a height-adjustable tennis
set once six exercise and six nutrition goals are achieved. In addition, Go4Fun leaders
will ask the children on a weekly basis if they have achieved their goal and prompt
them to reset them if they were too easy.

3.
Goal attainment reminders via text message and lottery style incentive: After the 10-week program, parents/ guardians will receive weekly mobile phone text
message reminders to support and encourage children to achieve their goals (and set
new ones where relevant). Parents/ guardians will be encouraged to text back with
goal achievements with each goal achieved being rewarded with a ticket entry (maximum
of eight tickets per month) into a prize draw (one per program) for a family pass
to a local zoo (or similar family activity, depending on local availability) that
will be drawn at 6 months.

Outcomes

Data will be collected for all participants at baseline, end of program, at 6 months,
and 12 months. The primary outcome is a mean change in BMI z score at 12-month follow-up. BMI z scores indicate how many units (of the standard deviation) a child’s BMI is above
or below the average BMI value for their age and sex. BMI z scores will be calculated from raw BMI measures using the Centers for Disease Control
growth reference data 46]. Secondary outcomes include anthropometric measures (body weight, height, and waist
circumference) assessed according to standardized procedures 47] and behavioral measures collected via validated questionnaires (Table 1). Similar to the BMI z scores, waist measures in centimeters will be converted to a waist circumference
z score based on reference data 46]. The Physical Activity Enjoyment Scale (PACES) will be used to assess physical activity,
and this tool has been found to have good internal consistency, item-total correlations,
and validity in primary school children (n?=?564) 48]. Scores were also correlated with task goal orientation, athletic competence, physical
appearance and self-reported physical activity 48]. For nutrition questions, we selected relevant questions from the NSW Centre for
Public Health Nutrition recommendations for nutrition questions 49]. These questions are recommended for practical assessment and have been developed
based on evidence and guidelines for children 49]. An adapted version of the Rosenberg Self-Esteem Scale will be used and is one of
the most widely used self-esteem measures in social science research 50]. This scale has been tested for reliability and validity in many languages and has
been found to be effective including in children 50].

Table 1. Primary and secondary outcomes (measured at baseline, end of program, 6 months, and
12 months)

Data collection

Data will be collected at baseline, end of program, 6 months, and 12 months by research
assistants. For baseline measures, staff members have been trained by the Better Health
Company investigator team in measuring height, weight, and waist circumference using
standardized procedures 47]. All participants will be contacted to attend the follow-up sessions, and they will
be incentivized with a gift voucher (value of $AUS25) for attending each of the 6-
and 12-month health checks These payments are to maximize the rate of follow-up for
the research study and are offered to both control and intervention site participants.
Data will be entered into a secure online database that will require minor additional
functionality for the collection of goal attainment and 6- and 12-month follow-up
data.

Sample size

Intraclass correlation was calculated based on preliminary data (214 individuals)
across the recruited 40 sites and was found to be 0.16 for the BMI z score. To detect a between-group difference of 0.24 (±0.43) in the BMI z score (based on outcome data from a previous Australian RCT examining 12-month weight
loss outcomes in children) 12], 12 participants from each of the 40 sites (20 intervention, 20 control) are required
to achieve 80 % power based on an alpha of 0.05.

Statistical analysis

Analysis will be conducted at the individual level and will follow the intention-to-treat
principle. The control and intervention groups will be compared on baseline characteristics
using independent t-tests for continuous variables or chi square tests for categorical
variables. For the primary outcome, the mean difference in BMI z score at 12 months between control and intervention groups will be analyzed after
adjusting for the baseline characteristics using regression models. Similar regression
models will be used for the secondary outcomes. These models will account for the
between-cluster variance and will be adjusted for baseline characteristics. All analyses
will be undertaken using SAS 9.4 for Windows (SAS Institute Inc. Cary, NC, USA), and
statistical significance will be set at P??0.05.

Process evaluation

Process evaluations explore the implementation, receipt, and setting of an intervention
and help in the interpretation of outcome results 51]. Information generated from the process evaluation will inform downstream translation
by informing policymakers and program developers about the intervention strengths,
weaknesses, and areas for improvement. We will use a mixed methods approach to investigate
why the incentive scheme may or may not have been effective/sustainable and which
intervention components were most influential. Four data sources will be used: (i)
quantitative data related to “reach” on participant attendance and outcomes described
above; (ii) for those in intervention group, participant and parent/guardian surveys
to examine intervention value, satisfaction, utility and health behaviors influenced;
(ii) semi-structured interviews with Go4Fun program leaders to investigate implementation
along with associated barriers and enablers; and (iv) focus groups with participants
and parents/guardians to explore uptake, acceptability and suggestions for improvement.
Taken together, qualitative data will explore participant and program leader views
on benefits, disadvantages, acceptability of and potential improvements for the incentive
scheme. To obtain a broad range of views, we will use a maximum variation sampling
method based on patient demographics and health service characteristics 52]. Sampling will continue until no new themes or categories emerge (“thematic saturation”).
Analyses will be thematic, and coding will be carried out inductively based on emergent
themes. NVivo 9 will be used to assist with interview data management.

Ethical approval

This study will adhere to the Australian National Health and Medical Research Council
ethical guidelines for human research. Lead ethical approval has been obtained from
the Sydney South Western LHD Research and Ethics Office (HREC/13/LPOOL/157), and necessary
governance clearances have been approved as follows: South West Sydney Human Ethics
Committee: HREC/14/LPOOL/480 and local project number: 14/278; South Eastern Sydney
Local Health District Research Governance: SSA/14/G/398; Western Sydney Local Health
District Research Governance: SSA/15/WMEAD/ 40; Hunter New England Local Health District
Research Governance: SSA/15/HNE/110; Northern Sydney Local Health District Research
Governance: SSA/15/HAWKE/110; and North Coast Local Health District Research Governance:
SSA/14/NCC/126. Written informed consent will be obtained from all child participants
and their parent/guardian prior to their participation. Participants will be free
to withdraw at any time.