I am often asked, regarding connected health, "What is the evidence base?"  The question is rooted in our Western beliefs that phenomena are orderly and things happen for a reason. Most agree that the highest degree of evidence comes from rigorous science and the most rigorous science comes about when comparing two identical groups, while varying only one thing between them.  This method of discovery is relatively easy in the lab, but becomes much more unwieldy when studying people and interventions in 'real life.'  Thus in clinical research, the gold standard is the randomized, controlled trial. 

Randomized trials are expensive, often lengthy, and really do not approximate reality. Subjects are usually compensated for participating, and we surround them with reminders that they are being studied, which may alter their behavior.  So clinical research, in an odd way, has some drawbacks, though it is the best way we know of to document whether a medical intervention makes sense.  Some practices are adopted because a large number of clinicians simply integrate them into work flow, not as the result of rigorous research.  The use of the stethoscope and coronary artery bypass surgery are two examples.

With these caveats in mind, I thought it would be a good idea to review the evidence base for one connected health intervention that is gaining adoption, telemonitoring for congestive heart failure (CHF). 

In general, patients with CHF are given equipment enabling them to transmit vital signs over a telecommunications network and interact with health care providers (usually nurses).  However, telemonitoring for CHF is not uniformly defined in the literature.  Some programs use weight only as a vital sign, whereas many incorporate blood pressure, heart rate and oximetry as well.  Some programs have telephone communication between providers and patients whereas some use 'videophones.'  Some programs treat a variety of folks with a variety of chronic illnesses, i.e. not just heart failure. Then there is the matter of what outcome to measure.  Some follow clinical outcomes such as death or worsening of CHF. Some follow hospital admissions (and in that group there are subgroups, i.e. 30, 60, 90 day admissions and CHF-related vs all cause readmissions).  Others have reported on bed days of care, homecare nurse utilization and other indirect efficiency measures.
Muddy waters you say? Indeed!!  But when asked by a public health jock or policy maker's well-meaning staffer, one can't ramble on like this. One has to have answers!

There are three large trials to review and some interesting ancillary studies.  The TEN-HMS study, published in 2003, showed that patients on telemonitoring had shorter hospital admissions and significantly better one-year mortality.  Another large trial, the WHARF trial published in 2005, showed that patients on telemonitoring had a significant reduction in mortality after six months.  Recently, the Veterans Administration published the results of its longitudinal study of over 17,000 veterans and showed that patients on home telemonitoring had a 25 percent reduction in bed days of care and a 19 percent reduction in admissions.  In a meta-analysis published in 2007, the authors found that remote monitoring programs reduced admissions by 21 percent.  Our own work at the Center for Connected Health has shown telemonitoring to be a promising intervention for our CHF patients.  In one study, we showed that telemonitoring led to a reduction in the number of skilled nursing visits for a homecare population and in another (6), we showed that a telemonitoring intervention decreased admissions by 50 percent over a six month period.

Presented this way, it is easy to see why some folks can say, legitimately, that the evidence base for CHF telemonitoring is solid.  Its use appears to be associated with improved mortality, decreased readmissions, decreased time in hospital and reduced need for skilled nursing visits.  On the other hand, studies are of varying degrees of rigor, compare slightly different outcomes, and use slightly different interventions. 

This leads me back to the 'real world' assessment.  For CHF, telemonitoring makes sense.  It teaches patients the relationship between salt intake, weight gain and pulmonary edema.  It enables them to care for themselves better at home and avoid the crisis visit to the emergency room which often turns into an admission.

The question we should be asking is not whether it is valuable, but rather how does it compare to other monitoring tools such as phone-based outreach (disease management) and intensive clinic-based monitoring.  These questions should form the substrate for the next wave of research on telemonitoring.