Assessing the user experience and usability of the PRECIOUS system: a randomized controlled trial in obese patients.

Objective To assess users' usability, satisfaction, acceptance and effectiveness of the PRECIOUS system to promote behavior change toward healthier lifestyles. Design: Thirty-one adult patients with BMI>30 (M = 44.23, SD = 5.91) were recruited and randomized into three conditions for a longitudinal study (3 months length): 1) Control group (TAU + biofeedback + follow-ups); 2) PRECIOUS only (app + biofeedback + follow-ups); 3) PRECIOUS + MI (app + biofeedback + motivational interviewing follow-ups). Main Outcome Measures: Usability, satisfaction, acceptance and effectiveness of PRECIOUS, and stages of change (S-Weight questionnaire). Results: The system was described as easy to use, flexible, fairly satisfying and good as a preventive health system. Participants rated biofeedback and the Physical Activity module as the most satisfying features. However, participants were unsatisfied with the Diet module. All additional features received acceptable scores in terms of satisfaction. Despite this, the PRECIOUS only group reported that they would probably recommend the system to others because it meets its purposes quite well. Conclusion: PRECIOUS was found a usable and acceptable solution, although improving several features in the Diet module in successive versions of the app would promote sustained use and satisfaction among users, possibly increasing its effectiveness in promoting healthier lifestyles. Abbreviations: ADA American Diabetes Association; BG2: BodyGuard2; BMI: Body Mass Index; CBT: Cognitive-behavioral therapy; EMA: Ecological Momentary Assessment; eHealth: Electronic health; mHealth: Mobile health; MI: Motivational interviewing; NCD: Non-communicable diseases; PA: Physical activity; PRECIOUS: PREventive Care Infrastructure based On Ubiquitous Sensing.