Scientists at the University of Chicago Medicine and Northwestern University argue that the commonly used definition of CPAP adherence—at least four hours of CPAP use per night—is inadequate. The amount of therapy that patients need varies from person to person nightly because it should align closely with how many hours they sleep, they say. 

So the researchers developed a new adherence metric alongside a new tool for monitoring adherence to CPAP therapy for patients and physicians. The resulting CPAP adherence module within a weight loss app integrates information from a wearable sleep and activity tracker and weight scale into a measurement for the percentage of time a user wears their CPAP relative to their objectively assessed time spent sleeping. 

“Sleep apnea can be effectively treated only when CPAP is used during the entire time spent in bed sleeping,” says Esra Tasali, MD, director of the UChicago Sleep Center and senior author of the paper, in a release. “We know that sleep patterns can vary considerably, so one-size-fits-all adherence guidelines are insufficient for most patients. By developing a tool for personalized CPAP treatment for sleep apnea, we are providing an opportunity for patients and providers to deliver and track therapy based on individual need.”

The research was published on December 5 in the Journal of Medical Internet Research.

Patients can unintentionally remove their CPAP devices during the night. Telling patients that four hours of CPAP use per night constitutes adequate treatment for their sleep apnea is “arbitrary and misleading,” Tasali says. “This guidance remains in common use today, despite a lack of strong evidence showing that it’s sufficient or has clear benefits for health outcomes.”

Unlike other therapies—such as medications—that continue to treat a health problem for hours after delivery, CPAP treatment is only effective while it is in use during sleep. That means four hours of CPAP wear might be an adequate “dose” for a patient who sleeps just four hours, but someone who sleeps for eight hours is getting the equivalent of a half-dose of treatment.

“The goal for therapy should be using the device for 100% of the time you spent in bed sleeping,” Tasali says. “By integrating a wearable sleep tracker, our tool provides a personal dose for CPAP therapy and a more meaningful metric for adherence monitoring that can be implemented into clinical guidelines.”

For the study, the Northwestern University team led by Bonnie Spring, PhD, and Angela Pfammatter, PhD, professors of preventive medicine, modified a weight-loss app they developed that tracks diet, physical activity, and weight. To support weight loss, the mobile technology system integrates information from a wearable sleep and activity tracker and weight scale. Since excess weight is a major risk factor for sleep apnea, the investigators modified the app to have it chart patients’ CPAP wear time and check it against a goal of wearing the device for 100% of time spent sleeping.

“The patients wanted to see the 100% goal displayed in the app as a target to reach every night,” Tasali says.

By showing progress toward a sleep goal alongside other icons that track progress toward diet, activity, and weight goals, the app helps people see how making improvements in one health behavior can make it easier to make changes in others.

“That’s important,” says Spring in a release, “because insufficient sleep, poor quality diet, physical inactivity, and overweight tend to occur together. It’s a great efficiency to have tools and strategies that can help people change multiple risk behaviors at the same time.”

Based on the patients’ feedback, the researchers added features like push notifications to remind users to wear their CPAP before bedtime. The new CPAP tracking technology could be used by physicians to deliver more comprehensive and effective sleep apnea treatment.

“Right now, it’s hard for providers to counsel the patient on how to optimally use their CPAP machine, as well as for the patient to grasp how much use is adequate every night,” Tasali says. “So, not only could this app be used as a self-management tool for patients, but also as a more accurate and personalized treatment efficacy monitoring method for healthcare providers.”

As a next step, the researchers are planning additional studies to test the tool against traditional methods for monitoring CPAP use to determine whether it improves patient adherence to therapy. In addition, Tasali hopes to study the impact of percent CPAP adherence on health outcomes such as blood pressure and sugar levels.

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