Using a digital health intervention “INTERCEPT” to improve secondary prevention in coronary heart disease (CHD) patients: protocol for a mixed methods non-randomised feasibility study [version 1; peer review: 2 approved]

Background: Digital health interventions (DHIs) are increasingly used for the secondary prevention of cardiovascular disease (CVD). The aim of this study is to determine the feasibility of “INTERCEPT”, a co-designed DHI developed to improve secondary prevention in hospitalised coronary heart disease patients (CHD). Methods: This non-randomised feasibility study will be conducted using a mixed methods process evaluation with a sample of 40 patients in an acute hospital setting. Informed by behaviour change theory, the Intercept application (I-App) integrates a smartphone interface, health care professional portal, a fitness wearable and a blood pressure monitor. I-App is designed to support and motivate patients to set goals, self-monitor lifestyle and medical risk factors, and manage their medications, with the health care professional portal enabling monitoring and communication with patients. Using convenience sampling, eligible patients will be recruited in two phases, a pre-implementation phase and an implementation phase. During the pre-implementation phase participants will not immediately receive the I-App but will be invited to receive the I-App at 3 months follow-up. This will enable early learning about the processes of recruitment and conducting the assessment prior to full scale deployment of the I-App. During the implementation phase, participants will be invited to download the I-App to their smartphone prior to hospital discharge. Qualitative interviews will be conducted among a subset of patients and health care professionals to gain a greater insight into their experience of using the I-App. Primary outcomes will be assessed at baseline and 3-month follow-up. Using pre-defined feasibility criteria, including recruitment, retention and engagement rates, together with data on intervention acceptability, will determine the appropriateness of progressing to a definitive trial. Discussion: This study will provide important insights to help inform the feasibility of conducting a definitive trial of “INTERCEPT” among coronary heart disease patients in a critical health care setting.