Rewards-based systems work to bring people into an online health management program, but they don't do much to encourage sustained engagement, according to a study recently published in the Journal of Internet Medical Research.

The study, conducted by researchers at the University of Toronto in Canada, looked at 140,000 potential users of an online health intervention called My Health eSupport. About half of the patients were recruited via an airline miles website, with the promise of 10 frequent flyer miles for completing a health risk assessment and an additional 10 miles for enrolling in the support program. The other half were simply recruited via the Heart and Stroke Risk Foundation website.

The rewards were successful in getting sign-ups: 52 percent of the experiment group enrolled in the program, compared to just 4 percent of the control group. Researchers found people gaining rewards were 27 times as likely to enroll. Both groups dropped off dramatically before the next step after enrolling, "assessing their readiness for change and selecting a priority area for lifestyle change." Only 13 percent of the rewards group and 8 percent of the control group completed that step.

When it came to the second assessment six weeks later, the control group had actually passed up the rewards group in terms of percent participation, with 24 percent participation to the experiment group's 21 percent.

Notably, the study didn't offer ongoing rewards to either group, using the rewards only as a way to "get people in the door." But the study shows that immediately after receiving their last reward, most participants dropped out. This illustrates an oft-cited criticism of rewards-based health behavior change strategies: By offering up extrinsic rather than intrinsic rewards, programs create only a superficial dedication to health, rather than the meaningful development of healthy habits.

"Our findings suggest that a single exposure of loyalty rewards may be used to encourage individuals to enroll in an internet-based preventative health program, but additional strategies are required to maintain engagement level," the authors conclude. "Future studies need to examine the schedules of loyalty reward reinforcement on the long-term engagement level of internet-based health programs."

This news comes just a few days after Walgreens announced an update to its Walgreens Balance Rewards program to better line up with the methods of influential behavior change expert BJ Fogg. Walgreens employs a number of strategies over and above extrinsic rewards.

The reward model in digital health has been a staple for years and has led to at least two acquisition deals. Rewards platform Earndit was bought by Lupe Fiasco's health kiosk company higi at the end of last year, and social health management company Welltok bought IncentOne a few months before that.