Association between obesity and heart rate variability indices: an intuition toward cardiac autonomic alteration - a risk of CVD.

BACKGROUND: Obese people have a higher prevalence of cardiovascular disease, which is supposed to be due to autonomic dysfunction and/or metabolic disorder. The alterations in cardiac autonomic functions bring out the changes in the heart rate variability (HRV) indicators, an assessing tool for cardiac autonomic conditions. OBJECTIVE: To compare the cardiac autonomic activity between obese and normal weight adults and find out the highest association between the indices of HRV and obesity. METHODS: The study was conducted in 30 adult obese persons (body mass index [BMI] >30 kg/m2) and 29 healthy normal weight controls (BMI 18-24 kg/m2). Short-term HRV variables were assessed using standard protocol. Data were compared between groups using Mann-Whitney U test. Obesity indices such as waist circumference, hip circumference, waist-hip ratio (WHR), and BMI were measured and calculated, and they were correlated with HRV indices using Spearman's correlation analysis. RESULTS: In the obese group, there was a significant increase in the mean heart rate, whereas the HRV parasympathetic indicators were less (eg, root mean square of differences of successive RR intervals [28.75 {16.72-38.35} vs 41.55 {30.6-56.75} ms, p=0.018], number of RR intervals that differ by >50 ms, that is, NN50 [15.5 {2-39} vs 83.5 {32.75-116.25}, p=0.010], etc) and the sympathetic indicator low frequency (LF)/high frequency (HF) ratio (1.2 [0.65-2.20] vs 0.79 [0.5-1.02], p=0.045) was more than that of the normal weight group. Spearman's correlation between HRV and obesity indices showed significant positive correlation of WHR with LF in normalized unit (r=0.478, p<0.01) and LF/HF ratio (r=0.479, p<0.01), whereas it had significant negative correlation with high frequency power ms2 (r=-0.374, p<0.05) and HF in normalized unit (r=-0.478, p<0.01). There was a nonsignificant correlation of BMI with HRV variables in obese individuals. CONCLUSION: Increased WHR, by far an indicator of visceral adiposity, was strongly associated with reduced cardiac parasympathetic and increased sympathetic activity in obese individuals defined by BMI. However, BMI itself has a weak relationship with HRV cardiac autonomic markers. Thus, even with a slight increase in WHR in an individual, there could be a greater risk of cardiovascular morbidity and mortality brought about by cardiac autonomic alterations.

Association of high-sensitivity C-reactive protein and uric acid with the metabolic syndrome components.

Metabolic syndrome (MetS) has been found to be associated with inflammatory molecules. This study was conducted among 125 MetS patients at B P Koirala Institute of Health Sciences, Dharan, Nepal to find an association of high-sensitivity C-reactive protein (hs-CRP) and serum uric acid with MetS components. Anthropometric measurements, blood pressure, medical history and blood samples were taken. Estimation of hs-CRP, serum uric acid, blood glucose, triglyceride and high density lipoprotein (HDL) cholesterol was done. hs-CRP had positive correlation with blood glucose (r = 0.2, p = 0.026) and negative with HDL cholesterol (r = -0.361, p < 0.001). Serum uric acid had positive correlation with waist circumference (r = 0.178, p = 0.047). Patients with elevated hs-CRP and uric acid had higher waist circumference (p = 0.03), diastolic BP (p = 0.002) and lower HDL cholesterol (p = 0.004) than others. Elevated hs-CRP and high uric acid were individually associated with higher odds for low HDL cholesterol (7.992; 1.785-35.774, p = 0.002) and hyperglycemia (2.471; 1.111-5.495, p = 0.029) respectively. Combined rise of hs-CRP and uric acid was associated with severity of MetS (p < 0.001) and higher odds for hyperglycemia (8.036; 2.178-29.647, p = 0.001) as compared to individual rise of hs-CRP or uric acid. The present study demonstrates that hs-CRP and serum uric acid are associated with MetS components, and the combined rise of hs-CRP and uric acid is associated with the increase in severity of MetS.

Thyroid dysfunction in metabolic syndrome patients and its relationship with components of metabolic syndrome.

BACKGROUND: A growing body of evidence suggests that metabolic syndrome is associated with endocrine disorders including thyroid dysfunction. Thyroid dysfunction in metabolic syndrome patients may further add to cardiovascular disease risk thereby increasing mortality. This study was done to assess thyroid function in metabolic syndrome patients and evaluate its relationship with the components of metabolic syndrome. METHODS: A cross sectional study was carried out among 169 metabolic syndrome patients at B P Koirala Institute of Health Sciences, Dharan, Nepal. Anthropometric measurements (height, weight, waist circumference) and blood pressure were taken. Fasting blood samples were analysed to measure glucose, triglyceride, high density lipoprotein (HDL) cholesterol and thyroid hormones (triiodothyronine, thyroxine and thyroid stimulating hormone). RESULTS: Thyroid dysfunction was seen in 31.9 % (n = 54) metabolic syndrome patients. Subclinical hypothyroidism (26.6 %) was the major thyroid dysfunction followed by overt hypothyroidism (3.5 %) and subclinical hyperthyroidism (1.7 %). Thyroid dysfunction was much common in females (39.7 %, n = 29) than males (26 %, n = 25) but not statistically significant (p = 0.068). The relative risk of having thyroid dysfunction in females was 1.525 (CI: 0.983-2.368) as compared to males. Significant differences (p = 0.001) were observed in waist circumference between patients with and without thyroid dysfunction and HDL cholesterol which had significant negative correlation with thyroid stimulating hormone. CONCLUSIONS: Thyroid dysfunction, particularly subclinical hypothyroidism is common among metabolic syndrome patients, and is associated with some components of metabolic syndrome (waist circumference and HDL cholesterol).

Thyroid Dysfunction and Associated Risk Factors among Nepalese Diabetes Mellitus Patients.

Objectives. To assess thyroid function and associated risk factors in Nepalese diabetes mellitus patients. Methods. A cross-sectional study was carried out among 419 diabetes mellitus patients at B. P. Koirala Institute of Health Sciences, Dharan, Nepal. Information on demographic and anthropometric variables and risk factors for thyroid dysfunction was collected. Blood samples were analysed to measure thyroid hormones, blood sugar, and lipid profile. Results. Prevalence rate of thyroid dysfunction was 36.03%, with subclinical hypothyroidism (26.5%) as the most common thyroid dysfunction. Thyroid dysfunction was much common in females (42.85%) compared to males (30.04%) (p = 0.008) and in type 1 diabetes (50%) compared to type 2 diabetes mellitus (35.41%) (p = 0.218). Diabetic patients with thyroid dysfunction had higher total cholesterol, HDL cholesterol, and LDL cholesterol in comparison to patients without thyroid dysfunction. Significant risk factors for thyroid dysfunction, specifically hypothyroidism (overt and subclinical), were smoking (relative risk of 2.56 with 95% CI (1.99-3.29, p < 0.001)), family history of thyroid disease (relative risk of 2.57 with 95% CI (2.0-3.31, p < 0.001)), and female gender (relative risk of 1.44 with 95% CI (1.09-1.91, p = 0.01)). Conclusions. Thyroid dysfunction is common among Nepalese diabetic patients. Smoking, family history of thyroid disease, and female gender are significantly associated with thyroid dysfunction.