LOS ANGELES – Use of a mobile phone app alone or personal coaching with smartphone self-monitoring was no better than were simple paper handouts for reducing weight after 24 months in obese or overweight young adults, the prospective CITY trial shows.
Patients given the free Android app lost the least amount of weight, averaging –0.87 kg, –1.48 kg, and –0.99 kg at months 6, 12, and 24.
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Three handouts on healthy eating and physical activity from the Eat Smart, Move More North Carolina program were just as effective as use of a mobile phone app alone or in concert with personal training.
This was similar to mean losses of –1.14 kg, –2.25 kg, and –1.44 kg among controls, who received three handouts on healthy eating and physical activity from the Eat Smart, Move More North Carolina program and were not asked to self-monitor.
Patients randomly assigned to personal coaching plus smartphone self-monitoring lost the most weight at months 6, 12, and 24 (mean –3.07 kg, –3.58 kg, –2.45 kg).
This was significantly more than controls at 6 months (net effect –1.92 kg; P = .003), but not at 12 months or 24 months, according to results to be presented formally at Obesity Week 2015 and simultaneously published online (Obesity. 2015 Nov. doi:10.1002/oby.21226).
“Although conclusions can only be drawn about the specific app tested, the CITY trial sounds a cautionary note concerning intervention delivery by mobile applications alone,” principal investigator Laura Svetkey of Duke University, Durham, N.C., advised.
CITY (Cell Phone Intervention for Young Adults) involved 365 individuals aged 18-35 years with a body mass index of at least 25 kg/m2, and was described as the largest and longest comparative-effectiveness trial to examine theory-based behavioral weight loss interventions that may be suitable for widespread use. At entry, the average age was 29.4 years, 69.6% were women, and average BMI was 35 kg/m2.
The results are surprising because both active interventions included behavior principles and tools, and intervention engagement and study retention remained high, according to the researchers.
Participants continued to use the investigator-designed phone app an average of twice weekly for 2 years, and final weight measurements at 2 years were available in 86% of patients: 104 patients randomized to the cell phone (CP) app, 104 to personal coaching (PC), and 105 controls.
The lack of efficacy of the CP and PC interventions at 2 years may be in part related to the behavior of the control group, which had better-than-expected outcomes, Dr. Svetkey suggested. Based on observational data, the control group was expected to gain 1.5 kg per year, but instead, 22% had a clinically meaningful weight loss of at least 5%, which did not differ significantly from the CP and PC groups at 25.5% and 27.5%.
Notably, 54% of controls also reported using at least one commercial weight loss app during the trial. Mean weight change at 24 months, however, was similar in the control group among commercial app users and nonusers (–1.2 kg vs. –1.8 kg), she reported at the meeting, which was presented by the Obesity Society and the American Society for Metabolic and Bariatric Surgery.
It’s also possible the CP app was ineffective because its design wasn’t sufficiently compelling and couldn’t be individually tailored to adapt to participants’ behavior and needs, the authors noted.
The CP intervention was delivered solely through the Android app, which included goal setting, challenge games, and social support via a “buddy system” that allowed predetermined messages to be sent to a randomly assigned buddy participant. A free Bluetooth-enabled scale was used to automatically transmit weight through the smartphone to the study database. Self-management behaviors were prompted by the app based on a protocol-driven schedule.
“Indeed, future trials may need to consider rapid, responsive, relevant (R3) design in which rapid assessment of usage and outcomes allows for response design changes that keep the app relevant to users,” Dr. Svetkey and colleagues wrote.
CP also may have been ineffective because it lacked human contact, while the PC intervention included six weekly face-to-face sessions, followed by monthly telephone calls.
Although PC led to significantly greater weight loss than did the phone app at 6 months (net effect –2.19 kg; P less than .001) and 12 months (net effect –2.10 kg; P = .025), the effect size was smaller than in studies in older adults with more in-person sessions, suggesting that the dose or intensity may have been insufficient for a sustained effect or that this approach is less effective in younger than older adults.