Effects of Individualized Follow-Up With an App Postcardiac Rehabilitation: Five-Year Follow-Up of a Randomized Controlled Trial

Background Adherence to healthy behaviors initiated or adapted during cardiac rehabilitation (CR) remains a significant challenge, with few patients meeting guideline standards for secondary prevention. The use of mobile health (mHealth) interventions has been proposed as a potential solution to improve adherence to healthy behaviors after CR. In particular, app-based interventions have shown promise due to their ability to provide monitoring and feedback anytime and anywhere. Growing evidence supports the use of apps in post-CR settings to enhance adherence. In 2020, we demonstrated that individualized follow-up via an app increased adherence to healthy behaviors 1 year after CR. However, it remains uncertain whether these effects persist once the follow-up is discontinued. Objective This study aims to evaluate the long-term effects of individualized follow-up using an app, assessed 4 years after the intervention. Methods A single-blinded multicenter randomized controlled trial was conducted. Patients were recruited from 2 CR centers in eastern Norway. The intervention group (IG) received individualized follow-up through an app for 1 year, while the control group (CG) received usual care. After the 1-year follow-up, the app-based follow-up was discontinued for the IG, and both groups were encouraged to maintain or improve their healthy behaviors based on their individual risk profiles. The primary outcome was the difference in peak oxygen uptake (VO2peak). The secondary outcomes included exercise performance, body weight, blood pressure, lipid profile, exercise habits, health-related quality of life, health status, cardiac events, and physical activity. Linear mixed models for repeated measurements were used to analyze differences between groups. All tests were 2-sided, and P values ≤0.05 were considered statistically significant. Results At the 5-year follow-up, 101 out of the initial 113 randomized participants were reassessed. Intention-to-treat analyses, using a mixed model for repeated measurements, revealed a statistically significant difference (P=.04) in exercise habits in favor of the IG, with a mean difference of 0.67 (95% CI 0.04-1.29) exercise sessions per week. Statistically significant differences were also observed in triglycerides (mean difference 0.40, 95% CI 0.00-0.79 mmol/l, P=.048) and walking (P=.03), but these were in favor of the CG. No differences were found between the groups for other evaluated outcomes. Conclusions Most of the benefits derived from the app-based follow-up diminished by 4 years after the intervention. Although the IG reported statistically significantly higher levels of exercise, this did not translate into improved VO2peak or exercise performance. Our study highlights the need for follow-up from health care providers to enhance adherence to healthy behaviors in the long term following CR. Trial Registration ClinicalTrials.gov NCT03174106; https://clinicaltrials.gov/ct2/show/NCT03174106 (original study protocol) and NCT05697120; https://clinicaltrials.gov/ct2/show/NCT05697120 (updated study protocol)