Sodium Intake and Mortality Follow-Up in the Third National Health and Nutrition Examination Survey (NHANES III)

Background  Sodium restriction is commonly recommended as a measure to lower blood pressure and thus reduce cardiovascular disease (CVD) and all-cause mortality. However, some studies have observed higher mortality associated with lower sodium intake. Objective  To test the hypothesis that lower sodium is associated with subsequent higher cardiovascular disease (CVD) and all cause mortality in the Third National Health and Nutrition Examination Survey (NHANES III). Design  Observational cohort study of mortality subsequent to a baseline survey. Participants  Representative sample (n = 8,699) of non-institutionalized US adults age ≥30, without history of CVD events, recruited between 1988–1994. Measurements and main results  Dietary sodium and calorie intakes estimated from a single baseline 24-h dietary recall. Vital status and cause of death were obtained from the National Death Index through the year 2000. Hazard ratio (HR) for CVD mortality of lowest to highest quartile of sodium, adjusted for calories and other CVD risk factors, in a Cox model, was 1.80 (95% CI 1.05, 3.08, p = 0.03). Non-significant trends of an inverse association of continuous sodium (per 1,000 mg) intake with CVD and all-cause mortality were observed with a 99% CI of 0.73, 1.06 (p = 0.07) and 0.86, 1.04 (p = 0.11), respectively, while trends for a direct association were not observed. Conclusion  Observed associations of lower sodium with higher mortality were modest and mostly not statistically significant. However, these findings also suggest that for the general US adult population, higher sodium is unlikely to be independently associated with higher CVD or all-cause mortality.     

Relations between QRS|T angle, cardiac risk factors, and mortality in the third National Health and Nutrition Examination Survey (NHANES III)

On the surface electrocardiogram, an abnormally wide QRS|T angle reflects changes in the regional action potential duration profiles and in the direction of the repolarization sequence, which is thought to increase the risk of ventricular arrhythmia. We investigated the relation between an abnormal QRS|T angle and mortality in a nationally representative sample of subjects without clinically evident heart disease. We studied 7,052 participants ≥40 years old in the third National Health and Nutrition Examination Survey with 12-lead electrocardiograms. Those with self-reported or electrocardiographic evidence of a previous myocardial infarction, QRS duration of ≥120 ms, or history of heart failure were excluded. Borderline and abnormal spatial QRS|T angles were defined according to gender-specific 75th and 95th percentiles of frequency distributions. All-cause (1,093 women and 1,191 men) and cardiovascular (462 women and 455 men) mortality during the 14-year period was assessed through linkage with the National Death Index. On multivariate analyses, an abnormal spatial QRS|T angle was associated with an increased hazard ratio (HR) for cardiovascular mortality in women (HR 1.82, 95% confidence interval 1.05 to 3.14) and men (HR 2.21, 95% confidence interval 1.32 to 3.68). Also, the multivariate adjusted HR for all-cause mortality associated with an abnormal QRS|T angle was 1.30 (95% confidence interval 0.95 to 1.78) for women and 1.87 (95% confidence interval 1.29 to 2.7) for men. A borderline QRS|T angle was not associated with an increased risk of all-cause or cardiovascular mortality. In conclusion, an abnormal QRS|T angle, as measured on a 12-lead electrocardiogram, was associated with an increased risk of cardiovascular and all-cause mortality in this population-based sample without known heart disease.     

Serum Cystatin C and Emphysema: Results from the National Health and Nutrition Examination Survey (NHANES)

Background  

Cystatin C (CysC) is a potent nonorgan-specific cysteine protease inhibitor and may contribute to elastolysis and tissue destruction by a mechanism of protease–antiprotease imbalance. Given the prevalence of CysC in the serum of smokers and its role in tissue destruction, we aimed to evaluate the association between CysC and emphysema.     

The metabolic syndrome and mortality from cardiovascular disease and all-causes: findings from the National Health and Nutrition Examination Survey II Mortality Study

The prospective associations between the metabolic syndrome as defined by the National Cholesterol Education Program (NCEP/ATP III) expert panel and mortality from cardiovascular disease and all-causes has not been extensively examined. Using data from the National Health and Nutrition Examination Survey II Mortality Study (1976-1992), the author examined the association between the metabolic syndrome and mortality from all-causes and cardiovascular disease among 2431 US adults aged 30-75 years. The NCEP/ATP III criteria were modified to substitute body mass index >/=25 kg/m(2) for waist circumference for women and >/=30 kg/m(2) for men. After multiple-adjustment, the hazard ratios for participants with the metabolic syndrome were 1.37 (95% confidence interval (CI): 1.02, 1.85) for mortality from cardiovascular disease, 1.29 (95% CI: 0.92, 1.82) for mortality from coronary heart disease, 1.68 (95% CI: 0.86, 3.27) for mortality from stroke, 1.23 (95% CI: 0.95, 1.59) for mortality from diseases of the circulatory system, and 1.15 (95% CI: 0.92, 1.45) for all-cause mortality compared with participants without the syndrome. The association between the number of metabolic syndrome criteria and mortality from cardiovascular disease was near linear (P = 0.007). Three criteria of the syndrome-excess weight, hypertriglyceridemia, and low high-density lipoprotein cholesterol concentration-were not independently associated with any of the outcomes. Additional prospective studies are needed to examine the association between the metabolic syndrome and the incidence of cardiovascular disease and mortality from cardiovascular disease and all-causes.     

Uric acid and mortality from all-causes and cardiovascular disease among adults with and without diagnosed diabetes: findings from the National Health and Nutrition Examination Survey III Linked Mortality Study

Using data from the National Health and Nutrition Examination Survey III Linked Mortality Study, uric acid concentration was significantly related to mortality from all-causes (978 diabetic participants: hazard ratio per mg/dl, 1.14; 95% confidence interval, 1.01-1.28; 12,824 nondiabetic participants: hazard ratio, 1.06; 95% confidence interval, 1.02-1.11) but not major CVD.     

Serum ascorbic acid and gallbladder disease prevalence among US adults: the Third National Health and Nutrition Examination Survey (NHANES III)

BACKGROUND: Ascorbic acid-deficient guinea pigs frequently develop gallstones, and ascorbic acid status may also affect the risk of gallbladder disease in humans. To examine the relationship of ascorbic acid, an antioxidant nutrient involved in cholesterol catabolism, to gallbladder disease, we analyzed data collected from a probability sample of US adults. METHODS: Analyses of data from 7042 women and 6088 men enrolled in the Third National Health and Nutrition Examination Survey, 1988-1994, were performed. Multiple logistic regression models stratified by sex were examined, controlling for the effects of age, race, diet, body mass index, and other potential confounders. RESULTS: A total of 761 women (11%) and 235 men (4%) reported a history of clinical gallbladder disease (symptomatic gallstones or cholecystectomy). Of the 9650 participants without a history of clinical gallbladder disease or abdominal pain consistent with gallbladder disease, and with valid abdominal ultrasonography, 408 (8%) of 4863 women and 274 (6%) of 4787 men had asymptomatic gallstones. Serum ascorbic acid level was inversely related to prevalence of clinical and asymptomatic gallbladder disease among women, but not among men. Among women, each SD (27 micromol/L) increase in serum ascorbic acid level was independently associated with a 13% lower prevalence of clinical gallbladder disease (P = .006) and asymptomatic gallstones (P = .048). CONCLUSION: Ascorbic acid, which affects the catabolism of cholesterol to bile acids and, in turn, the development of gallbladder disease in experimental animals, may affect the risk of gallbladder disease among women.     

Association of C-reactive protein and microalbuminuria (from the National Health and Nutrition Examination Surveys, 1999 to 2004)

Chronic kidney disease and cardiovascular disease share many risk factors. Injury to the vascular endothelium, measured by elevated levels of serum C-reactive protein (CRP), may play a role in kidney and cardiovascular disease. We therefore examined the association of CRP with microalbuminuria, a marker of early kidney injury. We conducted a cross-sectional analysis of a nationally representative, population-based survey. Weighted multiple logistic regression was used to study the association between CRP and microalbuminuria, adjusting for well-known risk factors. CRP was analyzed by a continuous variable and two categorized variables using quartiles and clinically recommended cutpoints. CRP concentration was positively associated with microalbuminuria. In the multivariate model, a one unit (in milligrams per liter) increase in CRP concentration was associated with a 2% increased odds of microalbuminuria (odds ratio 1.02, 95% confidence interval [CI] 1.01 to 1.02, p=0.0003). When CRP concentrations were stratified by clinically recommended cutpoints, compared with persons with CRP concentrations<1 mg/dl, persons with CRP concentrations between 1 and 3 mg/L and >3 mg/L were 1.15 times (95% CI 0.94 to 1.42) and 1.33 times (95% CI 1.08 to 1.65) more likely to have microalbuminuria, respectively. In subgroup analyses, the strength of association was comparable or stronger. In conclusion, elevated CRP levels were associated with microalbuminuria in a large, nationally representative data set. Vascular inflammation, as measured by CRP, may be a common contributor to early heart and kidney disease.     

Relationship between Mediterranean Diet Score and atherothrombotic risk: Findings from the Third National Health and Nutrition Examination Survey (NHANES III), 1988–1994

Background

Mediterranean diet has been promoted as the preferred dietary model for cardiovascular disease prevention in the United States.

Objective

We sought to evaluate the degree to which the Mediterranean diet is associated with reduced levels of atherothrombotic biomarkers in a population-based sample in the U.S.

Design

Data from 13,197 adults between the ages of 18 and 90 were collected and atherothrombotic risk factors assessed as part of the NHANES III, 1988–1994. Adherence to the Mediterranean diet was evaluated using food frequency questionnaires, supplemented by the 24-h dietary recall data, to develop Mediterranean Diet Scores (MedDietScore) that were analyzed in tertiles. The cross-sectional relationship of MedDietScore to atherothrombotic factors were analyzed using multiple variable regression analysis adjusted for complex sampling design using SUDAAN.

Results

The components of the Mediterranean diet and the dietary pattern's associations with atherothrombotic risk factors differed by age and gender. For men <45 years of age as MedDietScore increased: total cholesterol/HDL cholesterol (TC/HDL) ratio (p = 0.0390), serum insulin (p = 0.0414), and white blood cell (WBC) (p = 0.0246) decreased. For men ≥45 years as MedDietScore increased: TC/HDL ratio (p = 0.0008), Hemoglobin A1c (HgbA1c) (p = 0.0001), HOMA index (p = 0.0486), C-reactive protein (p = 0.0034), fibrinogen (p = 0.0028) decreased and HDL cholesterol (HDL-c) levels (p < 0.0001) increased. For pre-menopausal women, as MedDietScore increased: TC/HDL ratio (p < 0.0001), non-HDL cholesterol (p = 0.0012), apolipoprotein B (p = 0.0112), HgbA1c (p = 0.0001), decreased and HDL-c levels (p < 0.0001) increased. For post-menopausal women, as MedDietScore increased: TC/HDL ratio (p = 0.0005), Triglycerides (p < 0.0001), serum insulin (p = 0.0062), HOMA index (p = 0.0063) and Homocysteine (Hcy) (0.0046) levels decreased and HDL-c levels (p = 0.0005) increased.

Conclusions

Mediterranean diet appears to be associated with selective measures of cardioprotective lipid profiles, glucose metabolism, and inflammation and coagulation levels.     

The prevalence of low sex steroid hormone concentrations in men in the Third National Health and Nutrition Examination Survey (NHANES III)

Background Physiologic processes during ageing leading to multi‐morbidity and diseases that increase risk of premature death may be influenced by ageing‐associated changes in endogenous hormone production. Objective To evaluate the decline in sex steroid hormone levels across age and estimate the number of US men 40+ years old who may have low hormone levels. Design We measured serum testosterone, oestradiol and sex hormone binding globulin by immunoassay in 1351 men 20+ years old in Third National Health and Nutrition Examination Survey. We estimated free hormones by mass action. Results Free testosterone declined most rapidly with age (a 2% decline in geometric mean concentration occurred after ageing 1·3 years), followed by total testosterone (2·4 years), free oestradiol (4·1 years) and total oestradiol (8·1 years). These hormone changes with age translated into 25·0% and 30·2% of men 70+ years old having low total (which we defined as <10·4 nm ) and free (<0·17 nm ) testosterone, respectively, and 8·3% and 23·9% having low total (<73·4 pm ) and free (<2·2 pm ) oestradiol. Using population size projections between the 2000 and 2010 Censuses, we estimated that 8·4 (95% CI 4·7–12·2), 6·2 (3·1–9·2) and 6·0 (3·1–9·0) million men 40+ years old may have low total testosterone, free testosterone and free oestradiol, respectively. The prevalences were only modestly lower in men without prevalent chronic diseases. Conclusion Although no consensus exists for defining low hormone levels in ageing men, a substantial number of US men may have low sex steroid hormone levels, possibly putting them at risk for adverse health consequences and premature death.     

Heavy metals and cardiovascular disease: results from the National Health and Nutrition Examination Survey (NHANES) 1999-2006

We assessed the role of lead and cadmium as partial mediators between smoking and composite cardiovascular and cerebrovascular disease (CCVD). We also studied the association between urinary heavy metals and CCVD. Pooled data from NHANES 1999-2006 were examined. Cardiovascular and cerebrovascular disease was determined using a standardized questionnaire asking about history of stroke, angina, heart attack, coronary artery disease, and congestive heart failure. Increasing serum cadmium levels were associated with increasing prevalence of CCVD (P-trend: .03). Adjusted odds-ratio (OR) for active smokers versus never smokers was 2.09 (1.67-2.63). Adjustment for lead did not affect the OR but adjustment for cadmium significantly attenuated the OR (1.54 [1.17-2.03]). Significant association was observed between CCVD and urinary antimony, cadmium, cobalt, and tungsten. High levels of serum cadmium (>0.61 μg/L) were associated with CCVD. The relationship between smoking and CCVD was partially mediated through cadmium. Urinary antimony, cadmium, cobalt, and tungsten may be associated with CCVD.