Assessing the validity of childhood blood pressure screening: unbiased estimates of sensitivity, specificity, and predictive values.

Blood pressure measurement in childhood can be considered as a screening test for future blood pressure levels. Evaluating this test involves calculating sensitivities, specificities, and predictive values for a blood pressure measurement at an initial time for predicting underlying true blood pressure at a subsequent time. We demonstrate the use of childhood blood pressure tracking correlations that are corrected for within-person variability to calculate unbiased estimates of these test characteristics. In a cohort of 333 schoolchildren, we measured blood pressure on multiple visits in each of 4 successive years. Using these data for within-person variances and corrected tracking correlations, and U.S. population data for means and total variances, we tabulated positive predictive values, sensitivities, and specificities for the case of predicting a 9-year-old male's true systolic blood pressure 3 years later. For example, if a 9-year-old's average blood pressure from 4 visits is 115 mmHg, the probability of his true blood pressure being greater than 116 mmHg (90th percentile) at age 12 is 0.50. With longer follow-up, the use of predictive values, sensitivities, and specificities that incorporate corrected correlations should allow determination of the accuracy of predicting adult blood pressure from childhood values, and therefore the usefulness of screening children for those at high risk of developing hypertension.     

Isolated systolic hypertension in Dutch middle aged and all-cause mortality: a 25-year prospective study

In the early 1950s, the blood pressure of 3901 Dutch civil servants and their spouses aged 40-65 years was measured in a general health survey. Isolated systolic hypertension (systolic pressure greater than 160 mmHg, diastolic pressure less than 90 mmHg) was observed in 6.3% of the women and 3.0% of the men. The prevalence increased with age and it was more common in women in all age groups. Using logistic regression, with adjustment for potential confounders (age, smoking, serum cholesterol, Quetelet index, alcohol consumption, haemoglobin level, pulse rate and diastolic blood pressure) the association of 15- and 25-year total mortality with isolated systolic hypertension was determined. Compared to normotensive people (systolic pressure less than or equal to 135 mmHg, diastolic pressure less than 90 mmHg), the risk of death from all causes was significantly higher for men with isolated systolic hypertension after 15 and 25 years of follow-up (odds ratio OR = 2.4, 95% confidence interval (CI) 1.2-4.8 and OR = 3.2, 95% CI 1.3-8.0). For women 15-years mortality risk was strongly associated with isolated systolic hypertension (OR = 3.7, 95% CI 1.4-9.7). The increased risk was less pronounced after 25 years of follow-up (OR = 1.7, 95% CI 0.96-3.0). Our results support those of other studies and indicate that isolated systolic hypertension is an important independent risk factor for all-cause mortality. Since isolated systolic hypertension may be an indicator for the early onset of ageing, it is important to study its determinants and to pay more attention to its diagnosis and treatment in middle-aged populations.     

Migration, blood pressure pattern, and hypertension: the Yi Migrant Study.

Rural-urban migration provides an ideal opportunity to examine the effects of environment and genes on blood pressure. The effect of migration on the Yi people of China was studied. The Yi people live in a remote mountain area in southwestern China. In 1989, blood pressure was measured in 14,505 persons (8,241 Yi farmers, 2,575 urban Yi migrants, and 3,689 Han urban residents) aged 15-89 years. Different patterns were seen for men and women. Among the men, Yi farmers had the lowest mean blood pressure, the least rise in blood pressure with age (systolic blood pressure, 0.13 mmHg/year; diastolic blood pressure, 0.23 mmHg/year), and the lowest prevalence of hypertension (0.66%). In contrast, both Yi migrant men and Han men had higher levels of mean blood pressure, rise in blood pressure with age (Yi migrants: systolic pressure, 0.33 mmHg/year; diastolic pressure, 0.33 mmHg/year; Han: systolic pressure, 0.36 mmHg/year; diastolic pressure, 0.23 mmHg/year), and prevalence of hypertension (Yi migrants, 4.25%; Han, 4.91%). Among the women, however, mean systolic pressure was higher in Yi farmers than in Yi migrants or in Han. Diastolic pressure was similar among the three groups. However, the Yi farmer women's age-related rise in blood pressure (systolic pressure, 0.06 mmHg/year; diastolic pressure, 0.14 mmHg/year) and their prevalence of hypertension (0.33%) were lower than those in the other two groups. Yi migrant women had an intermediate rise in blood pressure with age (systolic pressure, 0.37 mmHg/year; diastolic pressure, 0.23 mmHg/year) and prevalence of hypertension (2.40%). Han women had the greatest rise in blood pressure with age (systolic pressure, 0.56 mmHg/year; diastolic pressure, 0.36 mmHg/year) and the highest prevalence of hypertension (4.76%). For both men and women, the above differences were only partially explained by age, body mass index, heart rate, smoking, and alcohol use. This study, using standardized methods, demonstrates an important effect of migration on rise in blood pressure with age and on the prevalence of hypertension.     

Correlates of urinary albumin excretion in young adult blacks and whites: the Coronary Artery Risk Development in Young Adults Study

The rate of urinary albumin excretion is an important risk factor for kidney failure, stroke, and cardiovascular disease, perhaps because higher albumin excretion reflects endothelial cell dysfunction. The authors characterized urinary albumin excretion according to blood pressure, diabetes mellitus, and other factors in 2,582 Black and White participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study who were aged 18-30 years in 1985-1986. Urinary albumin and creatinine concentrations were determined using single untimed samples 10 and 15 years later. The albumin:creatinine ratio was analyzed as a continuous variable and a dichotomous variable (higher albumin excretion, including microalbuminuria (25-249 mg/g) and macroalbuminuria (>or=250 mg/g)). Seventy percent of persons with increased albumin excretion were both normoglycemic and normotensive (systolic/diastolic blood pressure <140/90 mmHg and no use of antihypertensive drugs). Even when diabetic subjects, who have greater risk, were excluded, albumin excretion rose continuously as blood pressure increased among Blacks; increases started at systolic/diastolic blood pressures of 130/85 mmHg among Whites. Furthermore, blood pressure measured up to 15 years earlier predicted incident higher albumin excretion at year 15. These findings persisted after adjustment for age, body mass index, smoking, and blood lipid and plasma insulin levels. A risk of higher urinary albumin excretion exists at blood pressure levels below those commonly regarded as hypertension, with a greater risk among Blacks than among Whites.     

Isolated systolic hypertension in 14 communities

In the Hypertension Detection and Follow-up Program, 158,906 individuals from 14 communities around the United States had their blood pressure measured in their homes in 1972-1973. Of the total population screened, 2.4% had isolated systolic hypertension (systolic blood pressure greater than or equal to 160 mmHg and diastolic blood pressure less than 90 mmHg). Isolated systolic hypertension was present for 0.5% of those aged 30-39 years and 6.8% among those aged 60-69 years. The prevalence in blacks and women was greater than the prevalences in both whites and men. The prevalence among those taking antihypertensive medications at the time of screening was 6.1%, and 1.9% among those not on antihypertensive medications. From the individuals with "normal" diastolic blood pressure on the single home measurement (less than 90 mmHg), a random sample of 5,032 individuals were followed for mortality for eight years. Prevalence of isolated systolic hypertension was similar in this sample to that in the total. Among those not on antihypertensive medications, 8-year life table all-cause mortality rates adjusted for age, race, and sex were 17.6% for those with systolic blood pressure greater than or equal to 160 mmHg and 7.7% for those with systolic blood pressure greater than 160 mmHg. Among this population, all of whom had a diastolic blood pressure less than 90 mmHg, a multiple logistic analysis adjusting for baseline treatment status, age, race, sex, education, smoking, weight, pulse, physical activity, and systolic blood pressure revealed that each millimeter increase in systolic blood pressure was associated with approximately a 1% increase in mortality over the eight years of follow-up (p less than 0.05). Isolated systolic hypertension is both relatively common and a significant risk factor for subsequent mortality.     

The natural history of blood pressure in childhood

To find out whether there is a relationship between the level of blood pressure in childhood and later on in life, and whether future hypertensives can be identified early in life, we selected a random sample of 596 Dutch children. At the first examination they were 5-19 years of age. In 386 of them (65%) at least five consecutive annual blood pressure measurements were made between 1975 and 1982. The stability of a child's position in the blood pressure distribution ('tracking') was studied by linear regression of follow-up blood pressure on initial blood pressure. 'Tracking' coefficients were 0.4 to 0.6 mmHg/mmHg for systolic pressure, and 0.2 to 0.5 mmHg/mmHg for diastolic pressure after four years of follow-up. Twenty-seven per cent of the boys and 44% of the girls who were in the upper 10% of the systolic blood pressure distribution at the first examination were still there after four years. For diastolic pressure these figures were 25% and 22%, respectively. These observations indicate that there is a moderate degree of blood pressure 'tracking' in childhood. They further imply that it is impossible to detect future hypertensives early in life by measurement of blood pressure only.     

Designation of children with high blood pressure--considerations on percentile cut points and subsequent high blood pressure: the Bogalusa Heart Study

The effects of changing the percentile cut points of prior blood pressure measurements (both single and serial examinations) on prediction of subsequent high blood pressure, and of the definition of subsequent high blood pressure were assessed in 1,501 children from Bogalusa, Louisiana. Subjects were 2-14 years old at initial examination (year 1, 1973-1974) and were reexamined three, five, and eight years after the initial examination. Increasing the stringency of the prior measurement cut point resulted in increased specificity and positive predictive value, but decreased sensitivity and negative predictive value. For prediction of subsequent systolic blood pressure at the 90th percentile from year 1 levels, increasing the year 1 cut point from the 80th to the 95th percentile resulted in decreased sensitivity from 42.8 to 13.0%, and increased specificity from 83.0 to 97.3%. For systolic pressure, requiring all prior serial measurements to be above specified cut points resulted in further increases in specificity (maximizing at 100%) and decreases in sensitivity (minimizing at 2.1%). Using a year 1 cut point at the 90th percentile, increases in the definition of subsequent high blood pressure (from the 80th percentile to 140/90 mmHg or on treatment, respectively) resulted in increased sensitivity (from 20.5 to 33.3%) and negative predictive value, with decreasing specificity (from 93.9 to 91.3%) and positive predictive value. The results indicate that use of stringent criteria (serially at the 95th percentile) to identify children at risk for future essential hypertension will result in a substantial portion of the childhood population who will escape early identification but who will develop adult hypertension. Less stringent criteria will increase sensitivity and thereby provide the opportunity for primary prevention to a larger portion of the general childhood population who are at high risk for adult hypertension.     

长沙市13~18岁青少年高血压流行现状分析

目的了解长沙市中学生高血压流行现状,为进一步制定预防青少年高血压干预措施提供科学依据。方法采取分层整群抽样方法,对长沙市6区24所中学的16 843名年龄在13~18岁的中学生进行血压测量,用SPSS 18.0软件进行统计分析,两组计量资料的比较采用t检验,各组率间的比较采用χ2检验。结果本次调查的16 843名中学生中,平均收缩压为(103.90±10.42)mmHg,平均舒张压为(66.83±6.68)mmHg。相同年龄青少年,男生平均收缩压和舒张压均高于女生,差异有统计学意义(P0.001)。高血压前期和高血压检出率随着年龄增长呈现增加趋势。男生高血压前期和高血压检出率分别为10.34%(843/8 149)和15.35%(1 251/8 149),女生高血压前期和高血压检出率分别为3.45%(300/8 694)和5.16%(449/8 694)。同年龄不同性别高血压严重程度分布均存在差异,有统计学意义(P0.001)。结论长沙市13~18岁青少年高血压检出率较高,有必要将高血压前期和高血压青少年作为一级预防重点对象,采取有效综合干预措施来降低高血压的发病率。     

The prevalence and risk factors of hypertension in Klong Toey slum and Klong Toey government apartment houses

We have investigated the prevalence and factors associated with hypertension in 976 residents of Klong Toey Slum and 909 residents of government apartment houses, aged 30 and above, selected by probability sampling after systematic household surveys with an average response rate of over 80%. Hypertensives were those who had, on at least three measurements, average diastolic blood pressure equal to or above 95 mmHg and/or systolic blood pressure equal to or above 160 mmHg or had blood pressure below 160/95 mmHg but were currently on antihypertensive medication. The prevalence of total hypertensives were found to be 17.3% and 14.0% for residents of slum and government apartment houses respectively. Men and women had more or less equal mean blood pressure and similar prevalence of hypertension. The mean systolic blood pressure increased with age while the mean diastolic blood pressure, after an initial rise with age in lower age groups, tended to level off from the age group 55-64 years upwards. Only one quarter to one third were aware of their illness and less than 15% were receiving treatment. Significant risk factors include age, duration of smoking, duration of alcohol intake, high body mass index, high Cholesterol, high Triglyceride, high Low Density Lipoprotein Cholesterol (LDLC), low High Density Lipoprotein Cholesterol (HDLC), high Total Cholesterol (TC) to High Density Lipoprotein ratio (TC/HDLC), high LDLC to HDLC ratio and diabetes mellitus. The data suggested that hypertension was an important public health problem in low socioeconomic groups in Bangkok. Some of the risk factors were related to an unhealthy lifestyle which should receive due consideration in planning for appropriate control.     

Using the area under the curve to reduce measurement error in predicting young adult blood pressure from childhood measures

Tracking correlations of blood pressure, particularly childhood measures, may be attenuated by within-person variability. Combining multiple measurements can reduce this error substantially. The area under the curve (AUC) computed from longitudinal growth curve models can be used to improve the prediction of young adult blood pressure from childhood measures. Quadratic random-effects models over unequally spaced repeated measures were used to compute the area under the curve separately within the age periods 5-14 and 20-34 years in the Bogalusa Heart Study. This method adjusts for the uneven age distribution and captures the underlying or average blood pressure, leading to improved estimates of correlation and risk prediction. Tracking correlations were computed by race and gender, and were approximately 0.6 for systolic, 0.5-0.6 for K4 diastolic, and 0.4-0.6 for K5 diastolic blood pressure. The AUC can also be used to regress young adult blood pressure on childhood blood pressure and childhood and young adult body mass index (BMI). In these data, while childhood blood pressure and young adult BMI were generally directly predictive of young adult blood pressure, childhood BMI was negatively correlated with young adult blood pressure when childhood blood pressure was in the model. In addition, racial differences in young adult blood pressure were reduced, but not eliminated, after controlling for childhood blood pressure, childhood BMI, and young adult BMI, suggesting that other genetic or lifestyle factors contribute to this difference.     

The relationship between blood lead levels and blood pressure and its cardiovascular risk implications

The relationship between blood pressure and blood lead levels in the second National Health and Nutrition Examination Survey (1976-1980) has been examined for white males aged 40-59 years. After adjustment for age, body mass index, nutritional factors, and blood biochemistries in a multiple linear regression model, the relationship of systolic and diastolic blood pressures to blood lead levels was statistically significant (p less than 0.01). There was no evidence of a threshold blood lead level for this relationship. Although these data alone do not prove a casual relationship between low blood lead levels and blood pressure, the findings are consistent with current epidemiologic and animal studies, indicating that a causal relationship is probable. To examine the potential health risks, the multiple logistic risk factor coefficients from the Pooling Project and Framingham studies were used to predict the impact of the 37% decrease in mean blood lead levels which occurred in adult white males from 1976 to 1980. As a result of this blood lead decrease, the calculations predicted a 4.7% decrease in the incidence of fatal and nonfatal myocardial infarction over 10 years, a 6.7% decrease in the incidence of fatal and nonfatal strokes over 10 years, and a 5.5% decrease in the incidence of death from all causes over 11.5 years. In addition, as a result of this blood lead decrease, the predicted number of white males in this age group with hypertension (diastolic blood pressure greater than or equal to 90 mmHg) decreased by 17.5%.     

儿童期血压偏高对成年期高血压的影响研究

目的 本研究旨在探讨儿童期血压偏高对成年期高血压的影响,为成人高血压的早期防控提供科学依据。方法 基于“中国居民健康与营养调查”资料(1991-2011年),纳入儿童期(6~17岁)和成年期(18~38岁)均进行至少1次随访的研究对象。儿童期血压偏高前期定义采用中国儿童青少年血压参考值性别和年龄的第90百分位(P₉₀)至第95百分位(P₉₅),儿童期血压偏高采用≥P₉₅。成年期高血压前期为收缩压/舒张压≥120/80 mmHg且<140/90 mmHg;成年期高血压为收缩压/舒张压≥140/90 mmHg,或有高血压史,或目前正服用降压药物。采用协方差分析和Cox比例风险回归模型分析儿童期血压偏高对成年期高血压前期和高血压的影响,控制混杂因素包括儿童期性别和年龄,成年期的体重指数(BMI)、吸烟和饮酒。结果 本研究共纳入1 984名数据完整的研究对象,中位随访时间为11.7年。基线儿童期共有108人(5.4%)为血压偏高前期,199人(10.0%)为血压偏高。随访成年期共有697人(35.1%)为高血压前期,104人(5.2%)为高血压。协方差分析表明,成年期收缩压和舒张压水平均随着儿童期血压百分位的增加而增加(P_趋势<0.001)。多因素Cox回归分析显示,儿童期血压偏高者成年后为高血压前期的风险增加(HR=1.41,95%CI:1.12~1.77)。儿童期血压偏高者成年后为高血压的风险显著增加(HR=1.73,95%CI:1.01~2.98)。结论 儿童期血压偏高会增加成年期罹患高血压的风险。应该重视儿童青少年血压监测,对血压偏高的高危儿童应及时采取干预措施。     

Combining annual blood pressure measurements in childhood to improve prediction of young adult blood pressure

Tracking correlations of blood pressure (BP) have been reported between levels measured in a single year during both childhood and adulthood. Because of the variability of BP, these correlations increase with the number of visits and measurements per visit in each year. It remains unclear, however, whether such correlations would improve further by combining BP data collected over several years. From 1978-1981, BP was measured annually in a cohort of 339 children in East Boston, MA, at four visits one week apart with three measurements per visit. Of this cohort, then aged 18-26 years, 316 were re-examined in 1989-1990 at three visits one week apart with three measures per visit. Tracking correlations were estimated from levels measured in a single year as well as means averaged over several years in childhood, adjusting for age, year of measurement, as well as smoking, alcohol and oral contraceptive use. Multivariate models were fit to estimate tracking correlations from childhood to young adulthood adjusting for within-person variability. Using a single year in childhood, these were 0.49 in boys and 0.59 in girls for systolic BP and 0.39 and 0.48 for diastolic BP (all p<0.001). Using the long-term average in childhood and adjusting for variability across years, these values were 0.55 in boys and 0.66 in girls for systolic BP and 0.47 and 0.57 for diastolic BP (all p<0.001). We observed concomitant increases in the predictive value of childhood BP for young adult BP. These results suggest that averaging BP over at least two years during childhood increases tracking correlations and improves the prediction of adult values from childhood levels.     

Birth weight and body mass index in childhood, adolescence, and adulthood as predictors of blood pressure at age 36.

STUDY OBJECTIVE--The purpose of this study was to investigate the relation between blood pressure at age 36, and birth weight and body mass index (BMI) in childhood, adolescence and adulthood. DESIGN--Prospective longitudinal survey over a period of 36 years in England, Scotland, and Wales. PARTICIPANTS--A nationally representative sample consisting of 3332 men and women born in one week in March 1946. Altogether 82% of these subjects had complete data for the present analysis. MAIN RESULTS--There was an inverse linear relation between birth weight and blood pressure at age 36. The relation between BMI and blood pressure at age 36 was initially inverse and became increasingly positive throughout life. Weight gain in childhood was positively associated with adult blood pressure, although less important than weight change in later life. The associations between blood pressure and birth weight, and blood pressure and adult BMI were independent, and together they accounted for no more than 4% of the variation in adult blood pressure. Both low birth weight (birth weight < or = 2.5kg) and high BMI at age 36 (BMI > 30kg/m2) were associated with hypertension (> 140/90mmHg), but the per cent population risk of hypertension attributable to low birth weight was less than 5%, and to high BMI less than 12%. CONCLUSIONS--Low birth weight and high BMI at age 36 were independently related to high blood pressure. A reduction in the percentage of low birthweight babies born in the fourth decade of this century would only have a negligible effect on the incidence of adult hypertension 30-40 years later.     

Multiple risk factor clustering and risk of hypertension in Japanese male office workers

Major risk factors associated with hypertension (a family history of hypertension, obesity, diabetes mellitus, hypercholesterolemia, hypertriglyceridemia, hyperuricemia, and increased white blood cell counts) were assessed in 5275 Japanese male office workers aged 23-59 years. After controlling for potential risk factors of hypertension, the odds ratio of hypertension compared with the absence of risk factors was 1.91, 2.65, 3.88, 6.54, and 8.18 for the presence of 1, 2, 3, 4, and > or = 5 risk factors, respectively (P for trend < 0.001). Systolic and diastolic blood pressure levels also increased in a dose-dependent manner as the number of risk factors increased. Among men not taking antihypertensive medication, the adjusted mean differences in systolic and diastolic blood pressures (mmHg) were 11.2 and 9.2 between men with the presence of > or = 5 risk factors and men without risk factors, respectively. These results indicate that the accumulation of risk factors is highly associated with the increased risk of hypertension in Japanese men.     

Heightened risk of hypertension among black males: the masking effects of covariables

This study examines the extent to which a set of 10 demographic, behavioral, and medical risk factors explain black/white differences in hypertension. Data are from a cross-sectional examination of San Francisco transit drivers aged 25-65 years surveyed during 1983-1985 as part of an occupational health study. The inherent restriction of the study population to bus drivers and the further restriction to males in this population (764 blacks and 224 whites) controlled for factors related to occupation and sex. Control of 10 additional potential risk factors, including age, education, body mass index, smoking, and intake of caffeine and alcohol was possible in the analytic phase of the study. The unadjusted prevalence of hypertension (systolic blood pressure greater than or equal to 140 mmHg, diastolic blood pressure greater than or equal to 90 mmHg, or current use of antihypertensive medications) was 36.1 per cent for black males compared with 30.8 per cent for white males. The greatest difference in prevalence was observed for black males aged 55-64 years, for whom the prevalence was 46 per cent higher than for white males the same age. Despite higher rates of hypertension, blacks in all age groups exhibited lower levels of most major risk factors for hypertension. As a result, the independent effect of race on hypertension was increased rather than attenuated when the 10 covariables were taken into account (odds ratio of 1.27 in the unadjusted analysis, increasing to 1.54 in the adjusted, multivariate analysis). That this set of risk factors did not explain the higher rates of hypertension among blacks suggests that racial differences may arise from as yet unrecognized environmental and/or individual factors. The results also indicate that the association between race and blood pressure may have been underestimated in past studies that have relied on unadjusted analyses, in which negative confounding or masking effects of covariables have not been considered.     

儿童期Korotkoff第Ⅳ、Ⅴ音的差异及对成年高血压的预测价值

目的 探讨儿童青少年期Korotkoff第Ⅳ音(K4)与第Ⅴ音(K5)的差异及对成年高血压的预测价值,为选择血压测量方案和制定儿童血压评价标准提供依据.方法 2005年追访1987年建立的"北京儿童血压研究"队列人群,基线儿童期K4、K5作为舒张压(DBP),采用WHO 1996年标准诊断基线儿童期高血压;成年期记录K5作为DBP,采用《中国高血压防治指南(2005年修订版)》诊断成年期高血压.比较儿童期K4、K5的差异及对成年高血压的预测价值.结果 1987年基线调查6～17岁学龄儿童2505人,2005年追访到412人.基线K4-K5差值的几何均数为(10.1±1.7)mm Hg(1 mm Hg=0.133 kPa),并随年龄增长而下降;除青春期外,其他年龄男女之间K4-K5的差异无统计学意义.各年龄组K4-K5差值的分布构成有统计学意义(P＜0.001),6～9岁、10～12岁、13～15岁、16～17岁分别有59.6%、60.5%、56.3%和45.1%的儿童K4与K5差值大于10 mm Hg.按WHO标准,采用K4、K5为DBP诊断高血压检出率分别为5.0%和2.4%.儿童期K4与成年期血压的相关程度优于K5;且能预测成年期高血压.结论 当使用汞测压计测量儿童血压时,采用K4记录DBP,能更真实地反映儿童血压水平,使不同儿童的DBP水平具有可比性;并且K4与成年DBP的关联度更高,即轨迹现象更强,更能体现儿童血压水平对成年高血压的预测价值.     

Prenatal methylmercury exposure as a cardiovascular risk factor at seven years of age.

Blood pressure in childhood is an important determinant of hypertension risk later in life, and methylmercury exposure is a potential environmental risk factor. A birth cohort of 1,000 children from the Faroe Islands was examined for prenatal exposure to methylmercury, and at age 7 years, blood pressure, heart rate, and heart rate variability were determined. After adjustment for body weight, diastolic and systolic blood pressure increased by 13.9 mmHg [95% confidence limits (CL) = 7.4, 20.4] and 14.6 mmHg (95% CL = 8.3, 20.8), respectively, when cord blood mercury concentrations increased from 1 to 10 microg/liter cord blood. Above this level, which corresponds to a current exposure limit, no further increase was seen. Birth weight acted as a modifier, with the mercury effect being stronger in children with lower birth weights. In boys, heart rate variability decreased with increasing mercury exposures, particularly from 1 to 10 microg/liter cord blood, at which the variability was reduced by 47% (95% CL = 14%, 68%). These findings suggest that prenatal exposure to methylmercury may affect the development of cardiovascular homeostasis.     

Cadmium exposure and hypertension in the 1999-2004 National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION: Cadmium induces hypertension in animal models. Epidemiologic studies of cadmium exposure and hypertension, however, have been inconsistent. OBJECTIVE: We aimed to investigate the association of blood and urine cadmium with blood pressure levels and with the prevalence of hypertension in U.S. adults who participated in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). METHODS: We studied participants > or = 20 years of age with determinations of cadmium in blood (n = 10,991) and urine (n = 3,496). Blood and urine cadmium were measured by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Systolic and diastolic blood pressure levels were measured using a standardized protocol. RESULTS: The geometric means of blood and urine cadmium were 3.77 nmol/L and 2.46 nmol/L, respectively. After multivariable adjustment, the average differences in systolic and diastolic blood pressure comparing participants in the 90th vs. 10th percentile of the blood cadmium distribution were 1.36 mmHg [95% confidence interval (CI), -0.28 to 3.00] and 1.68 mmHg (95% CI, 0.57-2.78), respectively. The corresponding differences were 2.35 mmHg and 3.27 mmHg among never smokers, 1.69 mmHg and 1.55 mmHg among former smokers, and 0.02 mmHg and 0.69 mmHg among current smokers. No association was observed for urine cadmium with blood pressure levels, or for blood and urine cadmium with the prevalence of hypertension. CONCLUSIONS: Cadmium levels in blood, but not in urine, were associated with a modest elevation in blood pressure levels. The association was stronger among never smokers, intermediate among former smokers, and small or null among current smokers. Our findings add to the concern of renal and cardiovascular cadmium toxicity at chronic low levels of exposure in the general population.     

Blutdruck in Deutschland 2008–2011

High blood pressure is one of the most important risk factors for cardiovascular diseases and chronic kidney disease. It is a main determinant of morbidity and mortality in Germany. In the German Health Interview and Examination Survey for Adults (DEGS1) the blood pressure of 7,096 adults aged 18–79 years was measured in a standardised way using oscillometric blood pressure devices (Datascope Accutorr Plus). The average of the second and third measurements was used for analysis. The mean systolic blood pressure was 120.8 mmHg in women and 127.4 mmHg in men, while the mean diastolic blood pressure was 71.2 mmHg in women and 75.3 mmHg in men. Blood pressure values were hypertensive (systolic blood pressure ≥?140 mmHg or diastolic blood pressure ≥?90 mmHg) in 12.7?% of women and in 18.1?% of men. Hypertension (defined as having hypertensive blood pressure or taking antihypertensive medication in known cases of hypertension) was present in 29.9?% of women and 33.3?% of men. Almost 75?% of the survey’s highest age group, 70–79, had hypertension. DEGS1 demonstrates that high blood pressure remains a highly prevalent risk factor in the population at large. The methodology employed in measuring blood pressure has been improved as compared to that of the German National Health Interview and Examination Survey 1998 (GNHIES98) and it will be possible to draw comparisons soon, once a procedure for calibrating the 1998 data has been finalised. An English full-text version of this article is available at SpringerLink as supplemental.