Designing meaningful outcome parameters using mobile technology: a new mobile application for telemonitoring of patients with heart failure

Aims Health data captured by commercially available smart devices may represent meaningful patient-reported outcome measures (PROMs) in heart failure (HF) patients. The purpose of this study was to test this hypothesis by evaluating the feasibility of a new telemonitoring concept for patients following initial HF hospitalization. Methods and results We designed a cardio patient monitoring platform (CPMP) that comprised mobile iOS-based applications for patients' smartphone/smartwatch and the equivalent application on a physicians' tablet. It allowed for safe and continuous data transmission of self-measured physiological parameters, activity data, and patient-reported symptoms. In a prospective feasibility trial with 692 patient days from 10 patients hospitalized for newly diagnosed HF with reduced ejection fraction (mean left ventricular ejection fraction (LVEF) 26.5 +/- 9.8%), we examined the CPMP during the first 2 months following discharge (69 +/- 15 observation days per patient). The mean daily step count recorded by the mobile devices emerged as a promising new PROM. Its 14 day average increased over the study period (3612 +/- 3311 steps/day at study inclusion and 7069 +/- 5006 steps/day at end of study; P < 0.0001). It is unique for continuously reflecting real-life activity and correlated significantly with traditional surrogate parameters of cardiac performance including LVEF (r = 0.44; 95% CI 0.07-0.71; P = 0.0232), 6 min walk test (r = 0.67; 95% CI 0.38-0.84; P = 0.0002), and scores in health-related quality of life questionnaires. Conclusions We provide the first patient monitoring platform for HF patients that relies on commercially available iOS/watchOS-based devices. Our study suggests it is ready for implementation as a tool for recording meaningful PROMs in future HF trials and telemonitoring.