Predictors of racial differences in weight loss: the PROPEL trial
See Commentary, pg. 450.
Abstract
Objective
Studies have consistently shown that African American individuals lose less weight in response to behavioral interventions, but the mechanisms leading to this result have been understudied.
Methods
Data were derived from the PROmoting Successful Weight Loss in Primary CarE in Louisiana (PROPEL) study, which was a cluster-randomized, two-arm trial conducted in primary care clinics. In the PROPEL trial, African American individuals lost less weight compared with patients who belonged to other racial groups after 24 months. In the current study, counterfactual mediation analyses among 445 patients in the intervention arm of PROPEL were used to determine which variables mediated the relationship between race and weight loss. The mediators included treatment engagement, psychosocial, and lifestyle factors.
Results
At 6 months, daily weighing mediated 33% (p = 0.008) of the racial differences in weight loss. At 24 months, session attendance and daily weighing mediated 35% (p = 0.027) and 66% (p = 0.005) of the racial differences in weight loss, respectively. None of the psychosocial or lifestyle variables mediated the race-weight loss association.
Conclusions
Strategies specifically targeting engagement, such as improving session attendance and self-weighing behaviors, among African American individuals are needed to support more equitable weight losses over extended time periods.
CONFLICT OF INTEREST STATEMENT
Corby K. Martin received in kind support via donation of portion-controlled foods for this project from Health and Nutrition Technology and Nutrisystem. Research funds were provided to the institution of Dr. Martin by the following: Individuals Dedicated to Excellence and Achievement (IDEA) Public Schools, Louisiana LiftFund, WW (formerly WeightWatchers), Pack Health, American Society for Nutrition, RAND Corporation, Richard King Mellon Foundation, Evidation Health, Leona M. and Harry B. Helmsley Charitable Trust, the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Foundation for Food and Agriculture Research, National Institute for Health Research, National Science Foundation, and Eli Lilly and Company. Royalties from Access Business Group LLC (ABGIL) were paid to Dr. Martin via his institution as a result of licensing fees for SmartLoss, which includes a weight graph approach to facilitate adherence to dietary interventions. Dr. Martin has received consulting fees as a paid member of the scientific advisory boards of Wondr Health. Dr. Martin was paid to speak at the Obesity Action Coalition, and he is a paid member of the UAB Nutrition Obesity Research Center's External Advisory Board. Dr. Martin is a paid mentor for junior faculty seeking NIH funding at University of Nebraska Lincoln, and he is a paid facilitator for continuing education events from the Commission on Dietetic Registration and a paid planning committee member of Bray Course Planning Committee. Dr. Martin has received travel reimbursements from the following: Wondr Health and Commission on Dietetic Registration. Dr. Martin has US and European Patent applications for a body weight management and activity tracking system. Dr. Martin is a paid Data and Safety Monitoring Board (DSMB) member for Duke University, specifically Nia Mitchell's grant #R01 AG058725. Tina K. Thethi has received funding from grants/contracts from the following: Janssen Vaccines & Prevention B.V., Novo Nordisk A/S, Bayer, and Juvenile Diabetes Research Foundation (JDRF). Dr. Thethi received consulting fees and paid travel to meetings from Novo Nordisk A/S. Dr. Thethi received payments from Pri-Med for Council for Continuing Medical Education (CME) talks. Dr. Thethi was a paid member of the Bayer Advisory Board. Daniel F. Sarpong participates on the boards of New York University (NYU) Task Strengthening Strategy for hypertension control (TASSH), Nigerian Institute of Medical Research (NIMR) DSMB, Old School Hip Hop (5R21AG054536-02), and NYU AHA Addressing Social Determinants to Prevent Hypertension (RESTORE) Network DSMB. Carl J. Lavie serves on the DSMB for Novo Nordisk A/S. Eboni G. Price-Haywood serves on the PCORI Board of Governors. The other authors declared no conflict of interest.
Open Research
DATA AVAILABILITY STATEMENT
Complete deidentified data described in the article, code book, and analytic code are available from the Principal Investigator (PTK) by reasonable request pending the approval of the PROPEL publication committee.
