Evaluating the Effectiveness of Financial Incentives in Promoting Weight Loss Among Obese Individuals.

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.