JMIR Publications

ABSTRACT

Background:

Investigating participant engagement and non-usage attrition can help researchers identify which are the likely ‘active ingredients’ of eHealth interventions. Research on engagement can identify which intervention components predict health outcomes. Research on non-usage attrition is important to make recommendations for retaining participants in future studies.

Objective:

To investigate engagement and non-usage attrition in the Physical Activity Loyalty (PAL) scheme, a six month complex physical activity intervention implemented in workplaces in Northern Ireland. The intervention included financial incentives with reward redemption, and self-regulation techniques. Specific objectives included: (1) To determine whether engagement in specific intervention components predicted physical activity at six months; (2) To determine whether engagement in specific intervention components predicted mediators targeted by the intervention at six months; (3) To investigate predictors of non-usage attrition for participants recording daily activity via the PAL scheme physical activity monitoring system and logging onto the website.

Methods:

Physical activity was assessed at baseline and six months using pedometers (Yamax Digiwalker CW-701, Japan). Markers of engagement and website use, monitoring system use and reward redemption were collected throughout the scheme. Random-effects generalised least squares regressions determined whether engagement with specific intervention components predicted six month physical activity and mediator variables. Cox proportional hazards regressions were used to investigate predictors of non-usage attrition (days until first two week lapse).

Results:

A multivariable generalised least squares regression model (n=230) showed frequency of hits on the website's monitoring and feedback component (b=50.2, SE=24.5, P=.04) and percentage of earned points redeemed for financial incentives (b=9.1, SE=3.3, P=.005) were positively related to six month pedometer steps/day. Frequency of hits on the discussion forum (b=-69.3, SE=26.6, P=.009) was negatively related to six month pedometer steps/day. Reward redemption was not related to levels of more internal forms of motivation. Multivariable Cox proportional hazards regression models identified several baseline predictors associated with non-usage attrition. These included identified regulation (hazard ratio [HR]=0.88, 95% CI: 0.81, 0.97), recovery self-efficacy (HR=0.88, 95% CI: 0.80, 0.98), and perceived workplace environment safety (HR=1.07, 95% CI: 1.02, 1.11) for using the physical activity monitoring system to record daily activity. The EuroQol health index (HR=0.33, 95% CI: 0.12, 0.91), financial motivation (HR=0.93, 95% CI: 0.87, 0.99) and perceived availability of physical activity opportunities in the workplace environment (HR=0.96, 95% CI: 0.93, 0.99) were associated with website non-usage attrition.

Conclusions:

Our results provide evidence that opposes one of the main hypotheses of Self-Determination Theory by showing that financial rewards are not necessarily associated with decreases in more internal forms of motivation when offered as part of a complex multi-component intervention. Identifying baseline predictors of non-usage attrition can help future researchers to develop strategies and study designs to ensure maximum adherence to interventions in their intended form. Clinical Trial: ISRCTN17975376 (Registered 19/09/2014).