Interrelationships between obesity, obstructive sleep apnea syndrome and cardiovascular risk in obese adolescents.

BACKGROUND/OBJECTIVES: 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. SUBJECTS/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.

The Latin American Consortium of Studies in Obesity (LASO).

Current, high-quality data are needed to evaluate the health impact of the epidemic of obesity in Latin America. The Latin American Consortium of Studies of Obesity (LASO) has been established, with the objectives of (i) Accurately estimating the prevalence of obesity and its distribution by sociodemographic characteristics; (ii) Identifying ethnic, socioeconomic and behavioural determinants of obesity; (iii) Estimating the association between various anthropometric indicators or obesity and major cardiovascular risk factors and (iv) Quantifying the validity of standard definitions of the various indexes of obesity in Latin American population. To achieve these objectives, LASO makes use of individual data from existing studies. To date, the LASO consortium includes data from 11 studies from eight countries (Argentina, Chile, Colombia, Costa Rica, Dominican Republic, Peru, Puerto Rico and Venezuela), including a total of 32,462 subjects. This article describes the overall organization of LASO, the individual studies involved and the overall strategy for data analysis. LASO will foster the development of collaborative obesity research among Latin American investigators. More important, results from LASO will be instrumental to inform health policies aiming to curtail the epidemic of obesity in the region.

Interethnic differences in the accuracy of anthropometric indicators of obesity in screening for high risk of coronary heart disease.

BACKGROUND: Cut points for defining obesity have been derived from mortality data among Whites from Europe and the United States and their accuracy to screen for high risk of coronary heart disease (CHD) in other ethnic groups has been questioned. OBJECTIVE: To compare the accuracy and to define ethnic and gender-specific optimal cut points for body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) when they are used in screening for high risk of CHD in the Latin-American and the US populations. METHODS: We estimated the accuracy and optimal cut points for BMI, WC and WHR to screen for CHD risk in Latin Americans (n=18 976), non-Hispanic Whites (Whites; n=8956), non-Hispanic Blacks (Blacks; n=5205) and Hispanics (n=5803). High risk of CHD was defined as a 10-year risk > or =20% (Framingham equation). The area under the receiver operator characteristic curve (AUC) and the misclassification-cost term were used to assess accuracy and to identify optimal cut points. RESULTS: WHR had the highest AUC in all ethnic groups (from 0.75 to 0.82) and BMI had the lowest (from 0.50 to 0.59). Optimal cut point for BMI was similar across ethnic/gender groups (27 kg/m(2)). In women, cut points for WC (94 cm) and WHR (0.91) were consistent by ethnicity. In men, cut points for WC and WHR varied significantly with ethnicity: from 91 cm in Latin Americans to 102 cm in Whites, and from 0.94 in Latin Americans to 0.99 in Hispanics, respectively. CONCLUSION: WHR is the most accurate anthropometric indicator to screen for high risk of CHD, whereas BMI is almost uninformative. The same BMI cut point should be used in all men and women. Unique cut points for WC and WHR should be used in all women, but ethnic-specific cut points seem warranted among men.

Is TEE useful in patients with small subcortical strokes?

Although the role of transesophageal echocardiography (TEE) in the investigation of stroke mechanism is well established, the value of this test in patients with lacunar presentation is unclear. Review of 214 patients with acute cerebral ischemia referred for TEE to exclude cardioaortic sources of embolism after non-diagnostic basic work-up including carotid ultrasound and transthoracic echocardiography. TEE was considered positive when it showed large or complex aortic arch plaques, left atrial thrombus, mitral or aortic valve vegetations, or patent foramen ovale with atrial septal aneurysm. Multivariate regression analysis was performed to assess the value of lacunar syndrome and radiological small subcortical infarctions in predicting TEE result. Predictive values and likelihood ratios for these variables were calculated. Fifty-two patients (24%) had positive TEE. The most common embolic source was large or complex aortic plaques in 19% of patients. Neither clinical presentation with lacunar syndrome nor the presence of small subcortical infarction on CT scan predicted a negative TEE result on univariate or multivariate analysis. However, the combination of lacunar syndrome with radiological small subcortical infarction was uniformly associated with negative TEE (P=0.01; negative predictive value 100%). The combination of lacunar syndrome with small subcortical radiological infarct predicts the absence of cardioaortic sources of embolism on TEE in patients with acute cerebral ischemia.