Interrelationships between obesity, obstructive sleep apnea syndrome and cardiovascular risk in obese adolescents.
OBJECTIVE
Obstructive sleep apnea syndrome (OSAS) may be a cardiovascular disease (CVD) risk factor independently of obesity in adults. Pediatric studies have associated OSAS with endothelial dysfunction, but few studies have examined relationships between OSAS and macrovascular sequelae. Our objective was to examine OSAS's independent contribution to macrovascular CVD risk measures in obese adolescents.


METHODS
This cross-sectional observational study was conducted at Children's Hospital of Philadelphia Clinical Research and Academic Sleep Centers, and University of Pennsylvania Vascular Research Unit. Thirty-one obese non-diabetic adolescents underwent anthropometric measurements, overnight polysomnography, fasting laboratory draw and cardiovascular imaging. Cardiovascular outcome measures included maximal carotid intima-media thickness (cIMTmax), a measure of carotid structural changes, and carotid-femoral pulse wave velocity (CFPWV), an aortic stiffness measure whose relationship vis-à-vis OSAS in children has not been previously examined. Carotid diameter and augmentation index (AIx, measuring central pressure augmentation from wave reflections) were assessed. Potential confounding variables examined included blood pressure, lipoproteins, high-sensitivity C-reactive protein, insulin and glucose.


RESULTS
The apnea hypopnea index, a primary OSAS measure, was not associated with cIMTmax, carotid diameter, CFPWV or AIx. body mass index (BMI) associated positively with cIMTmax (r=0.52, P=0.006) and CFPWV (r=0.45, P=0.01). Mean asleep end-tidal CO2 was negatively associated with carotid diameter (r=-0.63, P<0.0005). Insulin levels were negatively associated with AIx (r=-0.53, P=0.02).


CONCLUSIONS
OSAS did not predict carotid structural changes or arterial stiffness independently of BMI in obese adolescents. Higher insulin levels associated with lower central pressure wave augmentation. Finally, long-term hypercapnia may predispose to carotid narrowing.
Pediatrics-Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL, USA.
D
D
Koren
Perelman School of Medicine and Philadelphia VA Medical Center, University of Pennsylvania, Philadelphia, PA, USA.
J A
JA
Chirinos
Pediatrics-Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
L E L
LE
Katz
Department of Medicine, Cardiovascular Division, Vascular Medicine Section, Perelman School of Medicine at the University of Pennsylvania,Philadelphia, PA, USA.
E R
ER
Mohler
Biostatistics Core, Clinical and Translational Research Center, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
P R
PR
Gallagher
Cardiovascular Engineering Inc, Norwood, MA, USA.
G F
GF
Mitchell
Pediatrics-Sleep Center, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA, USA.
C L
CL
Marcus
D000293:Adolescent; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D059168:Carotid Intima-Media Thickness; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008074:Lipoproteins / Q000378:metabolism; D008297:Male; D063766:Pediatric Obesity / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D015143:Philadelphia / Q000453:epidemiology; D017286:Polysomnography; D011237:Predictive Value of Tests; D063177:Pulse Wave Analysis; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D059289:Vascular Stiffness
D008074:Lipoproteins; D002097:C-Reactive Protein