SLEEP: Treatment for Apnea Needs Follow-Up Fine Tuning

SALT LAKE CITY, June 22 - Adherence to treatment with continuous positive airway pressure (CPAP) by patients with obstructive sleep apnea may be considerably less than believed.

A retrospective analysis of 528 new users of CPAP machines showed that only 17% were using them as prescribed, said Carl Stepnowsky, Ph.D., of the University of California at San Diego.

Another 63% "are below what we would usually consider to be acceptable, which is four hours a night," he reported here at Sleep 2006, the joint meeting of the Sleep Research Society and the American Academy of Sleep Medicine.

Moreover, he said, the failure to use the machines properly appears to begin almost immediately.

What's needed, Dr. Stepnowsky said, is more emphasis on follow-up and long-term treatment, rather on diagnosis and acute care. "There's so much emphasis on diagnosis and titration (of the CPAP pressure) and then it's like - here's a CPAP machine, go use it," he said in an interview.

"This is really about moving from an acute-care model to a chronic care model," he said.

Dr. Stepnowsky and colleagues looked at the records of more than 900 CPAP users from a San Diego sleep clinic, focusing on the 528 new users in the database. Patient adherence to CPAP was classified as poor if a patient used the machine less than four hours a night, while between four and six hours was acceptable, and greater than six hours was optimum.

The analysis found:

• Overall, patients used their machines 63% of the time.
• Mean CPAP adherence was 3.1 hours/night (SD=2.5; range=0.1-9.3).
• People with more severe apnea were likely to use their machines for longer durations (r=.268; P<.0001).

A parallel analysis looked at when the failure to adhere to the prescribed use began. The researchers grouped the patients according to their long-term adherence, and then looked at differences over the first month of use, Dr. Stepnowksy said.

It turned out, Dr. Stepnowksy said, that patients who would turn out to optimum users were good from the beginning, while those who would turn out to be poor users were already failing to adhere in the first month - and, in some cases, as early as the first day of treatment.

"As a physician, of course, you want to obtain as much adherence as you can," said Susheel Patil, M.D., of Johns Hopkins in Baltimore, who chaired the session in which Dr. Stepnowsky spoke.

But, Dr. Patil said, the adherence rates cited by Dr. Stepnowsky are "terrible when you look at the numbers, but it's not that bad when you compare it to other diseases," such as asthma or hypertension.

On the other hand, he said, a key point brought out by Dr. Stepnowsky is that failure to adhere starts early. For physicians, that means early follow-up "in order to improve adherence over time," Dr. Patil said, rather than waiting for weeks to assess the therapy.