An investigation into the relationship between sleep-disordered breathing, the metabolic syndrome, cardiovascular risk profiles, and inflammation between South Asians and Caucasians residing in the United Kingdom.

Department of Diabetes Research, University Hospitals of Leicester, NHS Trust, Leicester, United Kingdom.
Metabolic syndrome and related disorders (Impact Factor: 1.92). 01/2012; 10(2):152-8. DOI: 10.1089/met.2011.0073
Source: PubMed

ABSTRACT The aim of this study was to determine the prevalence of sleep-disordered breathing (SDB) in a South Asian and a Caucasian population and to compare the cardiovascular risk factors in those with SDB within these ethnic groups and determine if SDB is independently associated with the metabolic syndrome and markers of inflammation.
A total of 1,598 participants within a U.K. multiethnic population underwent an oral glucose tolerance test, completed the Berlin Sleep Questionnaire, and provided anthropometric data and fasting bloods. Metabolic syndrome was classified according to National Cholesterol Education Program Adult Treatment Panel III criteria.
The prevalence of SDB was 28.3% and did not differ between the two ethnic groups. South Asians with SDB had a higher body fat percentage (38.4±10% vs. 35.6±9%, P=0.016), glycosylated hemoglobin (5.6±0.5% vs. 5.6±0.5%, P=0.001) and lower high-density lipoprotein cholesterol (1.21±0.23 mmol/L vs. 1.29±0.34 mmol/L, P=0.002) compared to Caucasians with SDB, who were older (59.6±8.6 years vs. 50.4±10.3 years, P<0.001) and had higher systolic blood pressure (139.8±18.5 mmHg vs. 131.7±18.6 mmHg, P<0.001). SDB was associated with metabolic syndrome after adjustment for age, gender, ethnicity, and waist circumference (odds ratio=1.54, 95% confidence interval 1.12-2.09, P=0.01). There was no independent association between SDB and markers of inflammation.
The relationship between SDB and metabolic syndrome is not driven via the inflammatory pathway. The prevalence of SDB is significantly higher in those with metabolic syndrome although these South Asians had a greater cardiovascular disease (CVD) risk profile the relationship is independent of ethnicity. Routine screening for SDB within primary/secondary care may have a role in the prevention of CVD and type 2 diabetes mellitus.

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    ABSTRACT: Study Objectives: The South Asian population is at increased risk of cardiovascular disease. We compared the prevalence and severity of obstructive sleep apnea (OSA) in South Asians and white Europeans with severe obesity. Methods: Data from consecutive patients attending a specialist weight management service were analyzed. Self-reported age, gender, and ethnicity were recorded. Objective measurements of blood pressure, body mass index (BMI), and apnea-hypopnea index (AHI) were also acquired. Results: A total of 308 patients (72.7% women; 13% South Asian) were included, with mean age and BMI of 46 +/- 12 y and 49 +/- 8 kg/m(2), respectively. South Asians had significantly increased prevalence of OSA compared to white Europeans (85% vs. 66% [p = 0.017]) and were more likely to have severe OSA (42.5% vs. 21.6% [p = 0.015]). South Asians had significantly higher median AHI (24 events/h: interquartile range [IQR] 9.3-57.6 vs. 9 events/h: IQR 3.4-26.6; p < 0.01), significantly lower minimum oxygen saturation (76%: IQR 64% to 84% vs. 83%: IQR 77% to 87%; p < 0.01), and spent a significantly greater amount of time < 90% oxygen saturation (8.4%: IQR 1.0% to 24.3% vs. 2.4%: IQR 0.2% to 16.0%; p = 0.03). South Asian ethnicity, independent of demographics, BMI, and comorbidities, was associated with beta = 1.84 (95% CI: 1.27-2.65) increase in AHI+1 compared to white Europeans. Furthermore, we confirmed other independent OSA risk factors including increasing age, BMI, and male gender (all p < 0.001). Conclusions: Severely obese South Asians had significantly greater prevalence and severity of OSA than white Europeans. OSA may contribute to increased cardiovascular risk in South Asians compared to white Europeans with severe obesity. Mechanisms mediating the observed associations between these ethnicities require further investigation.
    Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine 09/2013; 9(9):853-8. DOI:10.5664/jcsm.2978 · 2.83 Impact Factor
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    ABSTRACT: Abstract Background: Obstructive sleep apnea (OSA) is often accompanied by the metabolic syndrome. Because both conditions are associated with depressed heart rate variability (HRV) separately, our aim was to study whether co-morbid OSA is associated with more reduced HRV in male patients with the metabolic syndrome. Methods: In this cross-sectional study, 35 men (age, 57±11 years) with the metabolic syndrome (according to International Diabetes Federation criteria) were included. OSA severity was defined by the apnea-hypopnea index (AHI). HRV was assessed by 24-hr ambulatory electrocardiographic monitoring. Standard deviation of all normal-to-normal RR intervals (SDNN), the high frequency power (HFP), and the ratio of low- to high-frequency power (LF/HF) were measured. Results: There were 14, 6, and 8 cases of severe (AHI ≥30/hr), moderate (15/hr≤AHI <30/hr), and mild (5/hr ≤AHI <15/hr) OSA, respectively. Seven patients had no OSA. Patients with mild-moderate or severe OSA had reduced SDNN and HFP values compared to those without OSA. Increasing OSA severity was associated significantly with lower daytime LF/HF ratio [standardized β regression coefficient (β)=-0.362, P=0.043] and higher night/day LF/HF ratio (β=0.377, P=0.023) after controlling for age, duration of diabetes, and severity of metabolic syndrome. Conclusions: Co-morbid OSA is associated with decreased overall HRV, parasympathetic loss, and impaired diurnal pattern of sympathovagal balance that may further increase the cardiovascular vulnerability of male patients with the metabolic syndrome. The role of the HRV analysis in the risk assessment of these patients warrants further studies.
    Metabolic syndrome and related disorders 12/2013; DOI:10.1089/met.2013.0111 · 1.92 Impact Factor
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