Ethnic and socioeconomic influences on childhood blood pressure: the Child Heart and Health Study in England

Ethnic differences in kidney function in childhood: the Born in Bradford Cohort Renal Study

Background: Endstage kidney failure rates are higher in South Asians than in White Europeans. Low birth weight is associated with adult chronic kidney disease and is more common in South Asians. Foetal kidney size was smaller in South Asians in the Born in Bradford (BiB) birth cohort. As part of BiB follow up, we aimed to investigate if there were ethnic differences in kidney function and blood pressure in early childhood and whether this was different by foetal kidney size. Methods: Serum creatinine, cystatin C, urea, and urinary albumin to creatinine ratio (ACR), protein to creatinine ratio (PCR) and retinol binding protein (RBP) were analysed in blood and urine samples from those who participated in the BiB follow-up at 7-11 years. Ethnicity was categorised by parental self-report as White European and South Asian. Estimated glomerular filtration rate (eGFR) was calculated using Schwartz, and cystatin C Zappitelli and Filler equations. Linear regression was used to examine the association between ethnicity and eGFR, PCR and blood pressure. Results: 1591 children provided blood (n=1403) or urine (n=625) samples. Mean eGFR was 92 ml/min/1.73m 2 (standard deviation (SD) 9) using Schwartz (n=1156) and 94 (SD 11) using Zappitelli (n=1257). CKD prevalence was rare (1 with eGFR <60 ml/min/1.73m 2, 14 (2.4%) had raised ACR (>2.5 mg/mmol in boys/3.5 mg/mmol in girls). Diastolic blood pressure was higher in South Asian children (difference 2.04 mmHg, 95% CI 0.99 to 3.10) but was not significant in adjusted analysis. There was no evidence of association in adjusted models between ethnicity and any eGFR or urinary measure at this age. Conclusions: There was no evidence of significant ethnic differences in kidney function at pre-pubertal age despite differences in kidney volume at birth. Longitudinal follow-up is required to track ethnic patterns in kidney function and blood pressure as children develop through puberty.

Racial differences of early vascular aging in children and adolescents

The prevalence of non-communicable disease (NCDs) is rising globally, with a large burden recorded in sub-Saharan countries and populations of black race/ethnicity. Accelerated vascular deterioration, otherwise known as early vascular aging (EVA), is the underlying factor for highly prevalent NCDs such as hypertension. The etiology of EVA is multifactorial with a central component being arterial stiffness with subsequent development of hypertension and cardiovascular complications. Although arterial stiffness develops with increasing age, many children and adolescents are subjected to the premature development of arterial stiffness, due to genetic or epigenetic predispositions, lifestyle and behavioral risk factors, and early life programming. Race/ethnic differences in pediatric populations have also been reported with higher aortic stiffness in black (African American) compared with age-matched white (European American) counterparts independent of blood pressure, body mass index, or socioeconomic status. With known evidence of race/ethnic differences in EVA, the pathophysiological mechanisms underlying graded differences in the programming of EVA are still sparse and rarely explored. This educational review aims to address the early life determinants of EVA in children and adolescents with a particular focus on racial or ethnic differences.

Impact of early-life diet on long-term renal health

In the last years, great advances have been made in the effort to understand how nutritional influences can affect long-term renal health. Evidence has accumulated that maternal nutrition before and during pregnancy and lactation as well as early postnatal nutrition is of special significance. In this review, we summarize epidemiologic and experimental data on the renal effects of perinatal exposure to energy restriction, low-protein diet, high-fat diet, high-fructose diet, and high- and low-salt diet as well as micronutrient deficiencies. Interestingly, different modifications during early-life diet may end up with similar sequelae for the offspring. On the other hand, molecular pathways can be influenced in opposite directions by different dietary interventions during early life. Importantly, postnatal nutrition significantly modifies the phenotype induced by maternal diet. Sequelae of altered macro- or micronutrient intakes include altered nephron count, blood pressure dysregulation, altered sodium handling, endothelial dysfunction, inflammation, mitochondrial dysfunction, and oxidative stress. In addition, renal prostaglandin metabolism as well as renal AMPK, mTOR, and PPAR signaling can be affected and the renin-angiotensin-aldosterone system may be dysregulated. Lately, the influence of early-life diet on gut microbiota leading to altered short chain fatty acid profiles has been discussed in the etiology of arterial hypertension. Against this background, the preventive and therapeutic potential of perinatal nutritional interventions regarding kidney disease is an emerging field of research. Especially individuals at risk (e.g., newborns from mothers who suffered from malnutrition during gestation) could disproportionately benefit from well-targeted dietary interventions.

Hemodynamic and ECG responses to stress test in early adolescent athletes explain ethnicity-related cardiac differences

BACKGROUND

Ethnicity is an important determinant of athletes' cardiovascular adaptation. Black adolescent and adult athletes exhibit a left ventricular (LV) hypertrophy with a concentric remodelling higher than their Caucasian counterparts. Scant data, however, are available on race-related differences in hemodynamic response of adolescent athletes to exercise and its relation with heart remodelling. We evaluated if race-specific, sport-related structural and electrical remodelling in adolescent athletes of Caucasian and African ethnicity exclusively depends on race itself rather than on different cardiovascular responses to physical exercise.

METHODS

We examined 90 adolescent athletes, 60 Caucasian (WA) and 30 Black (BA). All participants underwent thorough clinical, echocardiographic and stress test evaluations.

RESULTS

BA had greater indexed LV mass (LVM/BSA) with increased relative wall thickness (RWT) implying a concentric remodelling. BA showed higher systolic blood pressure (SBP) compared to WA during the whole exercise test. ECG data showed that BA vs WA had a significant shorter QRS duration in each step considered with a significant greater QT dispersion. BA reached a higher relative pressure peak as compared to WA. RWT was strongly influenced by ethnicity and less by SBP at peak of exercise (PE), although LVM/BSA was significantly related to SBP at PE and just marginally to age and not significantly to race.

CONCLUSIONS

Black adolescent athletes showed higher SBP during all steps of exercise associated to a different trend. Ethnicity was the main determinant of RWT, suggesting that LV geometry is principally race-related rather than influenced by a different hemodynamic profile to physical activity.

Heterogeneity in blood pressure in UK Bangladeshi, Indian and Pakistani, compared to White, populations: divergence of adults and children

Blood pressure (BP) and hypertension prevalence differences between UK South Asians (Bangladeshis, Indians and Pakistanis) and White Europeans exist in childhood and adulthood. This meta-analysis sought to quantify these differences. We searched MEDLINE (1946-2017), EMBASE (1974-2017) and GLOBAL HEALTH (1973-2017) for comparative studies and pooled the data with Revman (Cochrane Collaboration). Twenty-two studies were included-fourteen on adults and eight on children. South Asian adults had lower systolic and slightly lower diastolic BP. However, stark heterogeneity existed between South Asian subgroups: Bangladeshis had markedly lower systolic BP (mean difference: -11.7 mmHg in men and women), Indians slightly lower (-2.0 mmHg in men and -4.5 mmHg in women) and Pakistanis intermediately lower (-7.9 mmHg in men and -8.6 mmHg in women), compared to White Europeans. However, South Asian children did not have lower systolic or diastolic BP compared to White children, and their BP was often higher. This intergenerational change in BP difference mirrored the change in body mass index difference, particularly in Bangladeshis. We conclude that ethnicity-related BP differences are heterogeneous and dependent on age, sex and South Asian subgroup. South Asian children do not have lower BP than White Europeans in contrast to their adult counterparts. There is concern that this pattern may continue into adulthood, worsening the already high cardiovascular disease burden in South Asians in future years. Further research is needed to ascertain the causes of this evolving issue.

Associations of social and economic and pregnancy exposures with blood pressure in UK White British and Pakistani children age 4/5

South Asians have higher rates of coronary heart disease (CHD) than White European individuals. Blood pressure (BP) is one of the most important risk factors for CHD and ethnic differences in BP have been identified in childhood. Early life exposures could explain some of these differences. We examined associations of family social and economic and maternal pregnancy exposures and BP at age 4/5 in 1644 White British and 1824 Pakistani mother-offspring pairs from the Born in Bradford study. We found that systolic BP was similar but diastolic BP was higher, in Pakistani compared to White British children (adjusted mean differences were −0.170 mmHg 95% CI −0.884, 0.543 for systolic BP; 1.328 mmHg 95% CI 0.592, 2.064 for diastolic BP). Social and economic exposures were not associated with BP in either ethnic group. Maternal BMI was positively associated with BP in both groups but this association was mediated by child BMI. Only gestational hypertension was associated with child systolic and diastolic BP and this was only identified in Pakistani mother-offspring pairs. These findings suggest that Pakistani populations may have a different BP trajectory compared to White British groups and that this is already evident at age 4/5 years.

Sleep Duration and Risk of Type 2 Diabetes

BACKGROUND

Associations between sleep duration and type 2 diabetes (T2D) risk markers in childhood have been little studied. We examined associations between self-reported sleep duration and T2D risk markers in children.

METHODS

Cross-sectional study of 4525 multiethnic UK children aged 9 to 10 years. Sleep time was calculated from self-reported usual time of going to bed and getting up on a school day, validated in a subset using accelerometers. Fasting blood samples provided levels of serum lipids and insulin, plasma glucose, and HbA1c. Physical measures included height, weight, bioimpedance, and blood pressure. Multilevel linear regression models of anthropometric, T2D, and cardiovascular risk markers with sleep duration were adjusted for sex, age, month, ethnicity, socioeconomic position, observer (physical measures only), and random effect of school.

RESULTS

On average, children slept 10.5 hours per night (95% range 8.0-12.0 hours). There were strong inverse graded relationships between sleep duration, adiposity, and diabetes risk markers. In adjusted models, a 1-hour-longer sleep duration was associated with 0.19 lower BMI (95% confidence interval [CI] 0.09 to 0.28), 0.03 kg/m⁵ lower fat mass index (95% CI 0.00 to 0.05 kg/m⁵), 2.9% lower homeostasis model assessment insulin resistance (95% CI 1.2% to 4.4%), and 0.24% lower fasting glucose (95% CI 0.03% to 0.44%); there was no association with HbA1c or cardiovascular risk. Associations with insulin and glucose remained after an additional adjustment for adiposity markers.

CONCLUSIONS

The finding of an inverse association between sleep duration and T2D risk markers in childhood is novel. Intervention studies are needed to establish the causality of these associations, which could provide a simple strategy for early T2D prevention.

Screen time is associated with adiposity and insulin resistance in children

BACKGROUND

Higher screen time is associated with type 2 diabetes (T2D) risk in adults, but the association with T2D risk markers in children is unclear. We examined associations between self-reported screen time and T2D risk markers in children.

METHODS

Survey of 4495 children aged 9-10 years who had fasting cardiometabolic risk marker assessments, anthropometry measurements and reported daily screen time; objective physical activity was measured in a subset of 2031 children.

RESULTS

Compared with an hour or less screen time daily, those reporting screen time over 3 hours had higher ponderal index (1.9%, 95% CI 0.5% to 3.4%), skinfold thickness (4.5%, 0.2% to 8.8%), fat mass index (3.3%, 0.0% to 6.7%), leptin (9.2%, 1.1% to 18.0%) and insulin resistance (10.5%, 4.9% to 16.4%); associations with glucose, HbA1c, physical activity and cardiovascular risk markers were weak or absent. Associations with insulin resistance remained after adjustment for adiposity, socioeconomic markers and physical activity.

CONCLUSIONS

Strong graded associations between screen time, adiposity and insulin resistance suggest that reducing screen time could facilitate early T2D prevention. While these observations are of considerable public health interest, evidence from randomised controlled trials is needed to suggest causality.

Early origins of ethnic disparities in cardiovascular risk factors

BACKGROUND

Not much is known about the ethnic differences in cardiovascular risk factors during childhood in European countries. We examined the ethnic differences in childhood cardiovascular risk factors in the Netherlands.

METHODS

In a multi-ethnic population-based prospective cohort study, we measured blood pressure, left ventricular mass, and levels of cholesterol, triglyceride and insulin at the median age of 6.2years.

RESULTS

As compared to Dutch children, Cape Verdean and Turkish children had a higher blood pressure, whereas Cape Verdean, Surinamese-Creole and Turkish children had higher total-cholesterol levels (p-values<0.05). Turkish children had higher triglyceride levels, but lower insulin levels than Dutch children (p-values<0.05). As compared to Dutch children, only Turkish children had an increased risk of clustering of cardiovascular risk factors (odds ratio: 2.45 (95% confidence interval 1.18, 3.37)). Parental pre-pregnancy factors explained up to 50% of the ethnic differences in childhood risk factors. In addition to these factors, pregnancy and childhood factors and childhood BMI explained up to 50%, 12.5% and 61.1%, respectively.

CONCLUSIONS

Our results suggest that compared to Dutch children, Cape Verdean, Surinamese-Creole and Turkish children have an adverse cardiovascular profile. These differences are largely explained by parental pre-pregnancy factors, pregnancy factors and childhood BMI.

John MA, Gaskin DA, Molaodi OR, Harding S. Associations of blood pressure with body composition among Afro-Caribbean children in Barbados

Despite complex presentation of adult hypertension and a concomitant obesity epidemic, little is known about overweight in relation to blood pressure among Caribbean children. We examined blood pressure in relation to body size in a cross-sectional study of 573 Barbadian children aged 9–10 years (2010-2011).The United States normative blood pressure percentiles were used to identify children with high (≥ 95^th percentile) or high normal blood pressure (90^th – 95^th percentile). The World Health Organization body mass index cut-off points were used to assess weight status.

Birthweight and risk markers for type 2 diabetes and cardiovascular disease in childhood: the Child Heart and Health Study in England (CHASE)

AIMS/HYPOTHESIS

Lower birthweight (a marker of fetal undernutrition) is associated with higher risks of type 2 diabetes and cardiovascular disease (CVD) and could explain ethnic differences in these diseases. We examined associations between birthweight and risk markers for diabetes and CVD in UK-resident white European, South Asian and black African-Caribbean children.

METHODS

In a cross-sectional study of risk markers for diabetes and CVD in 9- to 10-year-old children of different ethnic origins, birthweight was obtained from health records and/or parental recall. Associations between birthweight and risk markers were estimated using multilevel linear regression to account for clustering in children from the same school.

RESULTS

Key data were available for 3,744 (66%) singleton study participants. In analyses adjusted for age, sex and ethnicity, birthweight was inversely associated with serum urate and positively associated with systolic BP. After additional height adjustment, lower birthweight (per 100 g) was associated with higher serum urate (0.52%; 95% CI 0.38, 0.66), fasting serum insulin (0.41%; 95% CI 0.08, 0.74), HbA1c (0.04%; 95% CI 0.00, 0.08), plasma glucose (0.06%; 95% CI 0.02, 0.10) and serum triacylglycerol (0.30%; 95% CI 0.09, 0.51) but not with BP or blood cholesterol. Birthweight was lower among children of South Asian (231 g lower; 95% CI 183, 280) and black African-Caribbean origin (81 g lower; 95% CI 30, 132). However, adjustment for birthweight had no effect on ethnic differences in risk markers.

CONCLUSIONS/INTERPRETATION

Birthweight was inversely associated with urate and with insulin and glycaemia after adjustment for current height. Lower birthweight does not appear to explain emerging ethnic difference in risk markers for diabetes.

Maternal educational level and blood pressure, aortic stiffness, cardiovascular structure and functioning in childhood: the generation R study

BACKGROUND

In adults, low level of education was shown to be associated with higher blood pressure levels and alterations in cardiac structures and function. It is currently unknown whether socioeconomic inequalities in arterial and cardiac alterations originate in childhood. Therefore, we investigated the association of maternal education with blood pressure levels, arterial stiffness, and cardiac structures and function at the age of 6 years and potential underlying factors.

METHODS

The study included 5,843 children participating in a prospective cohort study in the Netherlands. Maternal education was assessed at enrollment. Blood pressure, carotid-femoral pulse wave velocity, left atrial diameter, aortic root diameter, left ventricular mass, and fractional shortening were measured at the age of 6 years.

RESULTS

Children with low educated (category 1) mothers had higher systolic (2.80mm Hg; 95% confidence interval (CI) = 1.62-2.94) and diastolic (1.80mm Hg; 95% CI = 1.25-2.35) blood pressure levels compared with children with high educated (category 4) mothers. The main explanatory factors were the child's body mass index (BMI), maternal BMI, and physical activity. Maternal education was negatively associated with fractional shortening (P trend = 0.008), to which blood pressure and child's BMI contributed the most. No socioeconomic gradient was observed in other arterial and cardiac measurements.

CONCLUSIONS

Socioeconomic inequalities in blood pressure are already present in childhood. Higher fractional shortening among children from low socioeconomic families might be a first cardiac adaptation to higher blood pressure and higher BMI. Interventions should be aimed at lowering child BMI and increasing physical activity among children from low socioeconomic families.

Measures of socioeconomic position are not consistently associated with ethnic differences in cardiovascular disease in Scotland: methods from the Scottish Health and Ethnicity Linkage Study (SHELS)

BACKGROUND

Ethnic health inequalities are substantial. One explanation relates to socioeconomic differences between groups. However, socioeconomic variables need to be comparable across ethnic groups as measures of socioeconomic position (SEP) and indicators of health outcomes.

METHODS

We linked self-reported SEP and ethnicity data on 4.65 million individuals from the 2001 Scottish Census to hospital admission and mortality data for cardiovascular disease (CVD). We examined the direction, strength and linearity of association between eight individual, household and area socioeconomic measures and CVD in 10 ethnic groups and the impact of SEP adjustment.

RESULTS

There was wide socioeconomic variation between groups. All eight measures showed consistent, positive associations with CVD in White populations, as did educational qualification in non-White ethnic groups. For other SEP measures, associations tended to be consistent with those of White groups though there were one or two exceptions in each non-White group. Multiple SEP adjustment had little effect on relative risk of CVD for most groups. Where it did, the effect varied in direction and magnitude (for example increasing adjusted risk by 23% in Indian men but attenuating it by 11% among Pakistani women).

CONCLUSIONS

Across groups, SEP measures were inconsistently associated with CVD hospitalization or death, with effect size and direction of effect after adjustment varying across ethnic groups. We recommend that researchers systematically explore the effect of their choice of SEP indicators, using standard multivariate methods where appropriate, to demonstrate their cross-ethnic group validity as potential confounding variables for the specific groups and outcomes of interest.