New index for analysis of polysomnography, 'integrated area of desaturation', is associated with high cardiovascular risk in patients with mild to moderate obstructive sleep apnea.
BACKGROUND
Although obstructive sleep apnea (OSA) severity is evaluated by the apnea-hypopnea index (AHI), the value of AHI in evaluating cardiovascular risks, especially in mild to moderate OSA, is unclear.


OBJECTIVE
The purpose of this study is to evaluate the validity of a new index, the integrated area of desaturation (IAD), to detect the incidence of cardiovascular events (CVEs) in such patients.


METHODS
We enrolled 230 consecutive patients with mild to moderate OSA and 354 with severe OSA diagnosed by polysomnography, of whom 53 and 112, respectively, had CVEs. The IAD was calculated by dividing the area of desaturation by total sleep time in polysomnography. C-reactive protein (CRP) was also measured for all patients.


RESULTS
In the mild to moderate OSA patients, the mean IAD of the CVEs group was significantly higher than that of the non-CVE group (94.4 +/- 82.7 vs. 62.3 +/- 50.8, p = 0.001), whereas mean AHI and 3% oxygen desaturation index were similar in both groups. Multivariate analysis demonstrated that the IAD was an independent variable for CVEs (OR 1.006, 95% confidence interval 1.001-1.012, p = 0.031). Moreover, the IAD level of the high CRP group was significantly higher than that of the low CRP group (92.9 +/- 84.8 vs. 63.9 +/- 54.5, p = 0.009). There was no significant difference in AHI, IAD or other polysomnographic parameters in the severe OSA patients.


CONCLUSIONS
IAD might be superior to AHI alone in the evaluation of the history of CVEs in mild to moderate OSA patients, and it deserves attention as a possible predictor of future CVEs.
Asano
Kihiro
K
Department of Cardiology, Tokyo Medical University, Tokyo, Japan. kihiro24@sirius.ocn.ne.jp
Takata
Yoshifumi
Y
Usui
Yasuhiro
Y
Shiina
Kazuki
K
Hashimura
Yuki
Y
Kato
Kota
K
Saruhara
Hirokazu
H
Yamashina
Akira
A
D000328:Adult; D000368:Aged; D002097:C-Reactive Protein / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017286:Polysomnography; D015995:Prevalence; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000150:complications* / Q000453:epidemiology
D002097:C-Reactive Protein