Home telemonitoring of vital signs and cardiorespiratory signals in heart failure patients: System architecture and feasibility of the HHH model

Abstract

Background

The Home or Hospital in Heart Failure Study (HHH) is a European Community funded trial (QLGA-CT-2001-02424) which compares usual care of heart failure (HF) with three home-based interventions in a multicenter, multicountry (Italy, Poland and UK), randomized controlled clinical trial. Home telemonitoring (HT) of clinical parameters represents a potential alternative (or addition) to traditional home care models. Nocturnal respiratory disorders (periodic breathing, sleep apnea) are very common in HF, and are associated with increased morbidity and mortality. We developed an integrated HT system for monitoring of both vital signs and respiration. All measurements were patient-managed. This paper describes the architecture of this system, and assesses its feasibility.

Methods and results

461 clinically stable patients were randomized first to usual vs home-monitored care; the latter were further randomized to 3 strategies. Over a 12-month follow-up 2 of these 3 groups (195 patients, age: 60 ± 11 years, NYHA class II–III: 97%, LVEF 28 ± 7%) underwent self-administered home monitoring of vital signs (weekly — 12 parameters using an interactive voice response system) and respiration (monthly — 24-hour recording). Data were transmitted over conventional telephone lines; 81% of actually practicable vital signs measurements were completed by the patients (range: 75% (PL)–93% (UK)), as well as 92% of practicable respiratory recordings (range: 85% (PL)–99% (UK)). 87% of nighttime recordings were eligible for the study (good quality signals for ≥ 2.5 h).

Conclusions

This study, the largest so far, demonstrates that self-managed home telemonitoring of both vital signs and respiration is feasible in HF patients, with surprisingly high compliance. We found an excellent rate of acceptable nocturnal respiratory recordings, which are those with the greatest clinical relevance.

Introduction

Heart failure (HF) is now a major public health problem in industrialized countries [1], [2]. Mortality remains high, 4–8 times that of the age matched population [3]. HF accounts for 1–2% of health-care expenditure and 75% of this is due to rehospitalization [4]. Re-admission is common: about 10–20% of HF patients are readmitted with worsening of heart failure within 3 months from discharge and approximately 20–30% within 6 months [5]. New disease management models [6], [7] aim to reduce rehospitalization by early detection and treatment of deterioration, by telephone and home-based surveillance and management [5], [8]. Home telemonitoring (HT) of vital signs might integrate with these home care models. Previous studies of similar models gave mixed results [8], [9], [10], [11], [12], [13].

Nocturnal respiratory disorders (periodic breathing or sleep apnea) are very common in HF and are associated with increased morbidity and mortality [14], [15], [16]. Breathing disorders also often appear during wakefulness [17], [18]. Whether these breathing disorders relate to deterioration, including readmission, is unknown. Limited availability, high cost and low accessibility of polysomnography are major research impediments. Intermittent home telemonitoring of respiratory signals might be an alternative to polysomnography, if recording and transmission can be managed by the patients without specialized support.

We have therefore developed and evaluated an integrated home telemonitoring system to monitor vital signs and the respiratory signal, totally self-managed by patients, with minimal requirements for costly human resources. We carried out a multicenter, multicountry, randomized, controlled clinical trial HHH (Home or Hospital in Heart Failure) funded by the European Community (QLGA-CT-2001-02424) [19]. The study compares three levels of home telemonitoring of HF patients with usual care. This paper describes the architecture of the HHH telemonitoring system and provides a detailed report on its feasibility and patients' compliance.