Abstract
BACKGROUND: Most individuals with heart disease struggle to adhere to cardiovascular health behaviors, despite their known health benefits. Text message interventions (TMIs) are a promising treatment modality for health behavior promotion, but existing TMIs typically deliver a fixed set of messages and do not target well-being constructs associated with adherence and cardiovascular health. OBJECTIVE: To develop a 4-week TMI, which delivers daily messages to promote well-being and adherence to health behaviors and dynamically adapts based on participant feedback to deliver increasingly customized messages; and to assess its feasibility, acceptability, and preliminary efficacy in a single-arm, proof-of-concept trial in 14 individuals with coronary artery disease (age mean = 67.9, standard deviation = 8.7). METHODS: Participants received daily text messages related to well-being, physical activity, or diet, rated each message's utility, and these ratings informed the TMI's choice of future text messages. Feasibility was assessed by the proportion of messages successfully sent, and acceptability was assessed by participant ratings of intervention burden and text message utility. Finally, the intervention's preliminary efficacy was explored by measuring pre-post changes in psychologic and behavioral outcomes. RESULTS: The TMI was both feasible (93% of participants received all messages) and well-accepted (mean text message utility: 7.0 of 10 [standard deviation 2.5]; mean intervention utility: 6.4 of 10 [standard deviation 0.9]; mean intervention burden: 0.5 of 10 [standard deviation 0.9]). Participants reported that messages related to well-being were particularly helpful and that most messages led to an action (e.g., eating more vegetables, being kind to others). The TMI led to nonsignificant, small-to-medium effect size improvements in happiness, optimism, determination, depression, anxiety, self-rated health, and diet (d = 0.19-0.48), and, unexpectedly, small reductions in activity and physical function (d = -0.20 and -0.32). CONCLUSIONS: The adaptive TMI was feasible, well-accepted, and associated with nonsignificant improvements in psychologic outcomes and mixed effects on behavioral outcomes. Larger, well-powered studies are needed to determine whether this TMI will be able to improve well-being and health-related outcomes in this high-risk population.