Abstract P035: Accuracy of Self-Reported Weights Recorded Online: Results from the POWER Trial at Hopkins
Introduction: Websites are increasingly used to track weights during weight loss interventions, yet the accuracy of these self-reported weights is unclear.
Methods: This study examined the accuracy of self-reported weights recorded online among intervention participants in the Hopkins 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. All intervention participants (n=277) received a digital scale and were asked to track their weight weekly on a study website. In addition to website access, one treatment group was offered telephonic coaching and the other group was offered individual coaching and group sessions. Differences (self-reported weight - clinic weight) indicate under(-) or over(+) reporting using the closest self-reported weight recorded within 14 days of the weight taken by trained staff who were masked to treatment condition at the month 6 (n=231) and month 24 (n=205) follow-up clinic visits. The absolute value of the relative differences (absolute difference) describes the overall accuracy.
Results: Underestimation of self-reported weights increased (p<0.001) from month 6 [mean(SD)= -0.97(3.22) lbs] to month 24 [-2.37 (4.21) lbs]. The average absolute difference also increased (p<0.000) from month 6 [1.71(2.90) lbs] to month 24 [2.83(3.91) lbs]. Participants who achieved the study goal of 5% weight loss at 24 months had a lower absolute difference compared to those who did not meet this goal (p=0.018). No treatment effects were identified.
Conclusion: In this weight loss trial, self-reported weights recorded online were lower than weights taken in the clinic by trained staff. Participants who achieved 5% weight loss had less variability between self-reported weight and clinic weight compared to other participants.
- © 2013 by American Heart Association, Inc.