Elevated C-Reactive Protein in Patients With Obstructive Sleep Apnea
Background— Obstructive sleep apnea (OSA) has been increasingly linked to cardiovascular and cerebrovascular disease. Inflammatory processes associated with OSA may contribute to cardiovascular morbidity in these patients. We tested the hypothesis that OSA patients have increased plasma C-reactive protein (CRP).
Methods and Results— We studied 22 patients (18 males and 4 females) with newly diagnosed OSA, who were free of other diseases, had never been treated for OSA, and were taking no medications. We compared CRP measurements in these patients to measurements obtained in 20 control subjects (15 males and 5 females) who were matched for age and body mass index, and in whom occult OSA was excluded. Plasma CRP levels were significantly higher in patients with OSA than in controls (median [range] 0.33 [0.09 to 2.73] versus 0.09 [0.02 to 0.9] mg/dL, P<0.0003). In multivariate analysis, CRP levels were independently associated with OSA severity (F=6.8, P=0.032).
Conclusions— OSA is associated with elevated levels of CRP, a marker of inflammation and of cardiovascular risk. The severity of OSA is proportional to the CRP level.
Received February 27, 2002; revision received April 8, 2002; accepted April 8, 2002.