Evaluating the Effectiveness of Financial Incentives in Promoting Weight Loss Among Obese Individuals.
Condition: Obesity
MeSH terms: Weight Loss
Study type: Interventional

Summary: 
      Obesity is a major cause of premature aging and the second leading cause of preventable
      mortality in the United States, accounting for approximately 110,000 deaths per year.
      Financial incentives have been effective in modifying a number of health behaviors but they
      have rarely been applied to weight loss, and to the best of our knowledge never to weight
      loss by low-SES obese veterans.

      We propose testing two different approaches to using financial incentives to encourage weight
      loss. In the first, we build on previous work showing the effectiveness of 'deposit
      contracts', in which subjects are given the opportunity to put their own money at risk if
      they do not lose weight. In this incentive condition, subjects receive a direct payment
      conditional on daily weight loss, and an optional additional payment based on their own
      contributions to the deposit contract. We will match their contribution 1:1 to make the
      option of depositing their own money attractive to this predominantly low SES population. In
      the second approach we build on our own prior work using lotteries to promote drug adherence.
      In this incentive condition, participants are entered into a daily lottery, and receive any
      payoffs they earn from the lottery only if they stay on track with their weight-loss goal.
      Given their popularity in the general population, lotteries hold the promise of providing a
      cost-effective means of motivating weight loss and making efforts to lose weight more salient
      to obese patients.
    

Detailed description: 
      Fifty-seven obese patients at the Philadelphia VAMC (BMI between 30-40) will be randomly
      assigned to one of three conditions: weight monitoring only (WM), deposit contract incentive
      (DC$+WM), or lottery-based incentive (L$+WM). Exclusion criteria for the study will be
      minimal to maximize generalizability, focusing only on exclusions that may make participation
      unfeasible or unsafe (myocardial infarction within 6 months; uncontrolled hypertension,
      defined as BP>170 mm Hg systolic or BP>110 mm Hg diastolic; metastatic cancer, self-report of
      6 or more alcoholic beverages per day; schizophrenia; severe depression; active substance
      abuse; inability to read or severe cognitive deficits that would preclude ability to read
      consent form or fill out surveys). Patients with severe depression will be referred for
      treatment and considered ineligible until effectively treated. This exclusion is appropriate
      because those who are severely depressed are too ill to undertake weight reduction and
      because weight loss is often a symptom of severe depression. Subjects will also be asked how
      interested they are in losing weight (5 point scale, ranging from extremely uninterested to
      extremely interested, minimum score of 3 for inclusion). Subjects will be required to be
      between ages 30-70, as weight loss may be more difficult and less beneficial in the elderly.
      No other exclusions will be applied, as we aim to make the study as generalizable as
      possible. Initial screening of BMI's and comorbidities will be done using the VALOR data
      system at CHERP. Subjects who on paper meet criteria will then be sent letters and asked to
      call us if interested. The remaining eligibility criteria will be assessed over the phone,
      and subjects who meet the criteria will be invited for an in-person intake visit.

      At the initial intake visit, study procedures will be explained, and staff will create a
      linear graph depicting the course of weight loss required to lose 16 pounds over the course
      of 16 weeks (see figure). Subjects who provide written consent to participate will be
      randomized to one of the 3 arms at this visit. Participants randomized to one of the two
      incentive arms will be informed of the incentive plan (described in detail below).
      Physiologic measurements will be limited to weight and height which will be measured by our
      staff. To minimize fluctuations in weight due to diurnal variation, subjects will be asked to
      commit to having all morning appointments (e.g. between 8 and 1 pm) for both intake and f/u
      visits if possible. For those who cannot come in mornings, they will be asked to commit to
      coming in at approximately the same time in the afternoon for intake and f/u visits (e.g.
      between 2 and 4 pm). As soon as possible, following the intake visit, all participants will
      have a one-on-one consultation with a dietician (Kelly McBride) in which diet and exercise
      will be discussed. During this session, participants will receive guidance on strategies for
      weight loss.

      Following this consultation, participants will be asked to return to PVAMC to see the
      coordinator at CHERP once a month for each of four consecutive months to: be weighed (all
      participants), receive any payment they have earned (DC$+WM) or (L$+WM), and complete a
      follow-up questionnaire. Subjects will be instructed to drink only one 8 ounce glass of
      liquid and have a small breakfast and/or lunch (Examples of a small breakfast would be 2
      slices of whole grain toast with jelly or one serving of a whole grain cereal with skim milk
      or a piece of fruit and glass of skim milk. Light lunch could include any of the ones listed
      above, or a broth based soup or half of a turkey sandwich or half of a peanut butter) prior
      to coming in for follow-up visits. To compensate subjects for their time and trouble, all
      participants will receive a financial incentive each time they attend a monthly weigh-in,
      regardless of whether or not they have attained their monthly weight loss goal. Subjects will
      also receive a financial incentive for attending the initial intake visit and a financial
      incentive for attending their appointment with the dietician (Kelly McBride) and for coming
      to a f/u weigh in at 3 months after the incentives for weight loss cease. Those in the two
      incentives conditions will be provided with daily feedback, as described below. All such
      messages will be transmitted by text -enabled pagers that we will provide for the duration of
      the study for this purpose.

      Subjects will be asked to measure their weight each morning upon awakening, after urinating,
      but before eating or drinking and to transmit it to the study administrator by telephone (by
      leaving a message). We will provide scales that are accurate to 0.1 pounds to each subject
      for use for the duration of the study. We will tell participants at entry into the study that
      the scale is theirs to keep if they remain enrolled in the study for the duration but that
      they will be asked to return them if they drop out of the study before then. These scales
      will be calibrated initially to match the weights recorded by the scale used at CHERP.

      As mentioned above, there will be two different financial incentive conditions that we will
      be testing, both of which have a strong conceptual basis and for which there is suggestive
      evidence in the literature that these could be effective approaches to help obese patients
      lose weight.

      Patients randomized to the lottery financial incentives arm will be eligible for a daily
      lottery prize with an expected value of $3/day (a rough estimate of the savings per day to a
      health plan from reducing the incidence of type 2 diabetes and other consequences of obesity
      by achieving weight loss of 10-20 lbs) only if, prior to the lottery being resolved, they
      have reported a weight at or below their desired weight loss trajectory (see figure). The
      lottery is tailored both to provide infrequent large payoffs (a 1 in 100 chance at a $100
      reward) and frequent small payoffs (a 1 in 5 chance at a $10 reward). This is because lottery
      players are motivated by both a forward looking element (fixation on large $ amounts) and a
      backward looking element - how often did I win.

      The lottery is designed such that, each day, subjects who send their early morning weights
      will receive rapid feedback about whether they won, and non-adherent subjects will receive
      feedback about whether they would have won had they been adherent. Subjects will be asked to
      choose a 2-digit number upon entry into the study, e.g. "27". Each morning subjects will be
      asked to call in to report their weight from that morning. A two digit random number will be
      generated for each day. If the last digit includes either a "2" or "7" (which has
      approximately a 1 in 5 chance), and the subject reported a weight that was at or below their
      target weight for that day, they would be eligible to win $10. If the number is "27" (a 1 in
      100 chance) they would win $100. Information on whether they won would be transmitted to them
      each day, via text message, so that they receive this feedback immediately. If a subject does
      not report their weight that morning (by 12pm) or reports a weight that is above the target
      weight (with an allowance for the inaccuracy of the scale), they will be informed that they
      would have won the lottery that day had they been below target. We believe that a desire to
      avoid the regret associated with not winning, but learning that one would have won had one
      been adherent, will powerfully motivate subjects to adhere - beyond what one might anticipate
      based only on the expected value of the rewards. Moreover, this effect will probably
      strengthen with experience - i.e., after a given subject has experienced the remorse of
      failing to obtain rewards that they would have received if they had been adherent. Subjects
      who achieve a 20 pounds or more weight loss over the 16 weeks will be eligible for a one-time
      bonus of at least $50.

      Because the above daily weights are all self-reported, we will inform patients that they will
      only receive the calculated amount they are due if their weight at their monthly weigh-in is
      at or below their target weight (typically a 4 pound weight loss over 1 month). A 0.2 pound
      differential will be allowed between the office scale reading and the participant's reported
      weight at the time of their monthly visit to account for 0.1 pound scale variances on either
      the office or take home scales (e.g. if a subject loses 3.8 instead of 4.0 pounds per the
      office scale, they will receive their full incentive). These payments would be provided using
      the "Authorization and Invoice for Medical and Hospital Services Form" that allows
      participants to be paid directly through VA Agent Cashier.

      Deposit contract financial incentive ($+WM) participants will be paid a base amount
      corresponding to $3 for each day they are on track toward losing 16 pounds of weight by the
      end of the 16-week study. Specifically, they receive this payment for every day that their
      weight is at or below the ideal threshold line (see figure). In addition, these participants
      will be given the opportunity to contribute between $0-$3 per day of their own funds,
      refundable at the end of the month only if they have met or exceeded their monthly weight
      loss goal. As an incentive for participants to contribute to deposit contracts, we will match
      their money 1:1. Thus, participants in this condition have the opportunity to earn as much as
      $9 per day ($3 base payment plus their $3 plus our $3 match). Participants will decide at the
      beginning of each month how much, if any, they wish to deposit for the upcoming month. They
      can therefore change the amount of their deposit contracts from month to month. Any deposit
      contract money that is forfeited by participants because they do not lose a sufficient amount
      of weight will be contributed to a pool of money that will be divided equally among all
      subjects who lose 20 pounds or more over the 16 weeks. The size of this bonus will be not
      less than $50, with any shortfall to be made up by study funds. Because not all subjects will
      complete the study at the same time we will give each subject who is eligible for this bonus
      $50 at the final follow-up visit. If the eventual amount ends up being more, we will mail
      them a money order or the "Authorization and Invoice for Medical and Hospital Services Form"
      to make up the difference.

      Participants will be asked to self-monitor their weight on a daily basis and to transmit it
      to the central office by phone. Each morning before eating or drinking and after urinating,
      participants will be asked to a) weigh themselves in their pajamas, b) record their weights,
      and c) transmit their weight to the central office before 12 noon. To maintain comparability
      between the lottery and deposit contract groups, every afternoon, participants will receive a
      text message telling them whether they are below their threshold weight for payment and, if
      they are, how much they have received; if they are not at or below their threshold weight,
      how much they would have received if they had been. At their monthly weigh-in, participants
      will be given a report that captures how their report weights compare to the ideal weight
      loss trajectory sketched in the initial consultation session and giving them information on
      how much they will be paid if these weights are accurate, as well as how much they would have
      received if they had stayed on target.

      The daily monitoring provides participants with a constant reminder of their weight loss
      goals. This frequency was chosen based on the finding that people tend to adopt a narrow
      (daily) frame of reference to diets, "rededicating" themselves to it at the start of each
      day. The daily weigh-ins are designed to reduce binge eating by making participants
      constantly "accountable" for their weight. The monthly feedback provides encouragement and a
      symbolic reward for slow and steady weight loss.

      Falsification of weights will be minimized because patients will only get paid the amounts
      identified in the weekly reports if the degree of weight loss recorded at the monthly
      weigh-ins done by our coordinator are consistent with their self reports.

      A key aspect of the weight loss trajectory is that it can be reset at monthly intervals. This
      feature is critical in the likely event that a person falls short of attaining a monthly
      weight loss goal. Disheartened at the prospect of having to lose double the weight in order
      to get "back on track" by the end of the next month, such a person might drop out of the
      study. To avoid this problem, each person who has not reached the weight loss for the
      previous month will be given the opportunity for a "fresh start." The overall weight loss
      goal will stay the same, however, the slope of the trajectory will adjust (i.e. steepen) such
      that the participant need not "binge diet" following a month of poor weight loss performance
      (see "Fresh start trajectory" in figure, which assumes the subject lost 2 lbs. instead of 4
      lbs. in first month). Keeping the overall weight loss goal constant makes the procedure fair
      for those participants who maintain the ideal trajectory, while adjusting the slope of the
      weight loss line allows for subjects who have occasional slip-ups to stay engaged and get
      back on track.

      Our standard approach to receiving information from subjects will involve subjects calling us
      by telephone. We will not require subjects to have access to a home computer and electronic
      mail.

      Weight Monitoring only participants (control group) will be given the goal of losing 16
      pounds in 16 weeks but will receive usual care only, e.g. care provided by their regular
      clinical providers. They will not be given any financial incentive to lose the weight. They
      will be asked to come for a monthly f/u visit and weigh in, but will not receive any
      communications between these visits from the study coordinator.
    

Intervention name(s): Financial Incentives; Financial Incentives
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Participants call in their weight on daily basis. Participants must report under their daily targets to qualify for entry into lottery. Call-in weights are verified at monthly weigh-ins.; Participants call in their weight on daily basis. Participants must report under their daily targets to qualify to receive daily incentive. Call-in weights are verified at monthly weigh-ins.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Obesity; Weight Loss; Financial Incentives; Lottery; Deposit