Last Updated: 2009-07-28 18:19:07 -0400 (Reuters Health)

Nasal continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA) reduces levels of the inflammatory marker C-reactive protein (CRP), Japanese researchers report in the July issue of Chest.

"The role of OSA versus obesity in sleep apnea has been somewhat controversial," investigator Dr. Masahiko Kato told Reuters Health. "These data, showing that effective treatment of OSA lowers CRP, are suggestive of OSA itself being a factor in increasing CRP."

Dr Kato of Tottori University and colleagues note that a strong association has been reported between the degree of sleep-disordered breathing and serum levels of CRP. To gauge the effect of nasal CPAP on these findings, the researchers studied 55 patients with newly diagnosed OSA who were prescribed CPAP treatment.

At 6 months, there was a significant reduction from baseline in CRP levels. When the researchers divided the participants into "good" and "poor" compliance groups, this difference was no longer significant in the poor compliance group.

Moreover, further division into those with and without high CRP levels at baseline showed that a significant reduction was apparent only in good compliance patients with initially elevated CRP.

This may have cardiovascular implications, the researchers point out. However, Dr. Kato concluded that "whether CRP is important in raising the cardiovascular risk associated with OSA, and whether reducing CRP by treating OSA reduces that risk, remains to be determined."

Chest 2009; 136:125-129.