@Article{info:doi/10.2196/jmir.3332,
author="Jerome, Gerald J
and Dalcin, Arlene
and Coughlin, Janelle W
and Fitzpatrick, Stephanie
and Wang, Nae-Yuh
and Durkin, Nowella
and Yeh, Hsin-Chieh
and Charleston, Jeanne
and Pozefsky, Thomas
and Daumit, Gail L
and Clark, Jeanne M
and Louis, Thomas A
and Appel, Lawrence J",
title="Longitudinal Accuracy of Web-Based Self-Reported Weights: Results From the Hopkins POWER Trial",
journal="J Med Internet Res",
year="2014",
month="Jul",
day="15",
volume="16",
number="7",
pages="e173",
keywords="self-report; weight loss; obesity; Internet",
abstract="Background: Websites and phone apps are increasingly used to track weights during weight loss interventions, yet the longitudinal accuracy of these self-reported weights is uncertain. Objective: Our goal was to compare the longitudinal accuracy of self-reported weights entered online during the course of a randomized weight loss trial to measurements taken in the clinic. We aimed to determine if accuracy of self-reported weight is associated with weight loss and to determine the extent of misclassification in achieving 5{\%} weight loss when using self-reported compared to clinic weights. Methods: This study examined the accuracy of self-reported weights recorded online among intervention participants in the Hopkins Practice-Based Opportunities for Weight Reduction (POWER) trial, a randomized trial examining the effectiveness of two lifestyle-based weight loss interventions compared to a control group among obese adult patients with at least one cardiovascular risk factor. One treatment group was offered telephonic coaching and the other group was offered in-person individual coaching and group sessions. All intervention participants (n=277) received a digital scale and were asked to track their weight weekly on a study website. Research staff used a standard protocol to measure weight in the clinic. Differences (self-reported weight -- clinic weight) indicate if self-report under (-) or over (+) estimated clinic weight using the self-reported weight that was closest in time to the clinic weight and was within a window ranging from the day of the clinic visit to 7 days before the 6-month (n=225) and 24-month (n=191) clinic visits. The absolute value of the differences (absolute difference) describes the overall accuracy. Results: Underestimation of self-reported weights increased significantly from 6 months (mean -0.5kg, SD 1.0kg) to 24 months (mean -1.1kg, SD 2.0kg; P=.002). The average absolute difference also increased from 6 months (mean 0.7kg, SD 0.8kg) to 24 months (mean 1.3, SD 1.8kg; P<.001). Participants who achieved the study weight loss goal at 24 months (based on clinic weights) had lower absolute differences (P=.01) compared to those who did not meet this goal. At 24 months, there was 9{\%} misclassification of weight loss goal success when using self-reported weight compared to clinic weight as an outcome. At 24 months, those with self-reported weights (n=191) had three times the weight loss compared to those (n=73) without self-reported weights (P<.001). Conclusions: Underestimation of weight increased over time and was associated with less weight loss. In addition to intervention adherence, weight loss programs should emphasize accuracy in self-reporting. Trial Registration: ClinicalTrials.gov: NCT00783315; http://clinicaltrials.gov/show/NCT00783315 (Archived by WebCite at http://www.webcitation.org/6R4gDAK5K). ",
issn="1438-8871",
doi="10.2196/jmir.3332",
url="http://www.jmir.org/2014/7/e173/",
url="https://doi.org/10.2196/jmir.3332",
url="http://www.ncbi.nlm.nih.gov/pubmed/25042773"
}