At a follow-up of around four years, patients treated with CPAP had a slightly lower incidence of high blood pressure, heart attack, stroke, and other heart-related events than patients not treated with CPAP, but the difference was not found to be significant -- a finding the researchers themselves admitted, though, might have had a more positive outcome if the study had been longer or had more participants.
Use of CPAP for more than four hours per night did however appear to lower high blood pressure risk, suggesting that adherence with treatment may be critical in this group of patients.
CPAP: If at First You Don't Succeed…
The second study included close to 1,900 sleep apnea patients without high blood pressure who were followed for an average of 11 years.
Researchers from Zaragoza, Spain's, Hospital Universitario Miguel Servet found that patients who were prescribed CPAP but declined the treatment had about twice the risk for developing high blood pressure as people without sleep apnea.
Patients who were non-adherent with prescribed CPAP therapy had about an 80% greater risk.
Sleep specialist Yosef P. Krespi, MD, of Lenox Hill Hospital in New York City, says adherence with CPAP therapy could be improved if more clinicians worked with patients to get the treatment right.
As many as half of people who try CPAP abandon it after a few days or weeks, studies suggest.
"We used to tell patients who said they couldn't use CPAP not to worry about it," he tells WebMD. "Now we tell them to come back in and we work with them. We can readjust the pressure, change the mask, and even add a humidifier if it is too hot. We can do a lot of tweaking."