App stores are exploding with programs designed to help people monitor their health using a smart phone. But the majority of these apps merely make it easier for patients to record health measures, such as weight or blood pressure. It's unclear if they actually significantly improve health behavior.

Joseph Cafazzo, a biomedical engineer at the University Health Network, in Toronto, and collaborators have developed apps that do much more. Their apps interface wirelessly with medical devices—including a blood-pressure monitor and a blood-sugar monitor—and offer suggestions based on the readings. They found that people using the programs lowered their blood pressure and were more vigilant about monitoring and testing their blood sugar.

One of the most interesting findings was that doctors seemed to play no role in the change. "It was solely patients becoming responsible for their own care," says Cafazzo, who heads the university's Centre for Global eHealth Innovation.

Cafazzo's efforts were partly a result of the growing use of smart phones as medical tools, as well as an increase in remote and home monitoring devices that are moving medicine outside the doctor's office.

But unlike many existing monitoring systems, Cafazzo sees his work bringing greater responsibility to the patient. "The goal of classic home monitoring is to collect information and deliver it to the doctor, who has to analyze and act on it, then return that information to the patient," he says. "It's not really self-care."

In a yearlong clinical trial of the system involving 110 patients with diabetic hypertension, Cafazzo and colleagues had some people use the app and a home blood-pressure monitor, while others used only a monitor. Those who used the app had a drop in systolic blood pressure of 10 millimeters of mercury, on average, which would reduce the risk of cardiac events by about 25 percent. Those who used just the conventional pressure monitor saw no reduction in blood pressure.

Physicians didn't significantly alter patients' medication or treatment regimens during the course of the study, so researchers say any changes in health must have been solely due to the monitoring app and related changes in patient behavior, such as new eating patterns and better medication compliance. "Just giving the monitor isn't enough," says Cafazzo. "Active telemonitoring keeps patients engaged."