Cohort Profile: Mandela's children: the 1990 Birth to Twenty study in South Africa

The importance of birth cohort studies to low and middle income countries

In order to discern the causes of the health and developmental problems of children, and thence develop preventative strategies, longitudinal cohort studies offer major advantages. They can monitor the consequences of exposure to physical and psychological events and thence identify antecedents of various disorders. We describe the historical background to the development in the UK of this study design, and the uptake of longitudinal birth cohorts in low- and middle-income countries (LMICs), using the cohorts in Jamaica, South Africa and Brazil as exemplars. We describe the benefits of such studies and show how undertaking longitudinal cohort studies can have major health and financial benefits to the populations concerned. Additionally, the paper outlines the advantages of collaboration between studies and the pooling of data.

JA KIDS - Jamaica's second national birth cohort study: aims and methods

Birth cohort studies across the world have yielded information that has been used to inform policy and programme decisions that have improved the health and well-being of populations. A few such studies have been conducted in low- and middle-income countries due to funding, methodological and other challenges. This paper briefly reviews the methods of comprehensive birth cohort studies with extensive follow-up of participants through the life course conducted in low- and middle-income countries. It then reviews the first Jamaican birth cohort study of 1986 and discusses the methodological advances in implementing JA KIDS, the second Jamaican birth cohort study conducted in 2011. The aims and methods of JA KIDS are described in detail.

Properties of the full random-effect modeling approach with missing covariate data

During drug development, a key step is the identification of relevant covariates predicting between-subject variations in drug response. The full random effects model (FREM) is one of the full-covariate approaches used to identify relevant covariates in nonlinear mixed effects models. Here we explore the ability of FREM to handle missing (both missing completely at random (MCAR) and missing at random (MAR)) covariate data and compare it to the full fixed-effects model (FFEM) approach, applied either with complete case analysis or mean imputation. A global health dataset (20 421 children) was used to develop a FREM describing the changes of height for age Z-score (HAZ) over time. Simulated datasets (n = 1000) were generated with variable rates of missing (MCAR) covariate data (0%-90%) and different proportions of missing (MAR) data condition on either observed covariates or predicted HAZ. The three methods were used to re-estimate model and compared in terms of bias and precision which showed that FREM had only minor increases in bias and minor loss of precision at increasing percentages of missing (MCAR) covariate data and performed similarly in the MAR scenarios. Conversely, the FFEM approaches either collapsed at≥ $$ \ge $$ 70% of missing (MCAR) covariate data (FFEM complete case analysis) or had large bias increases and loss of precision (FFEM with mean imputation). Our results suggest that FREM is an appropriate approach to covariate modeling for datasets with missing (MCAR and MAR) covariate data, such as in global health studies.

Maximising the potential of Chinese birth cohort studies: a systematic review of mother-baby cohorts in mainland China

OBJECTIVES

There is now a growing interest in early-life influences on adult diseases in China. A number of birth cohorts have been established. This systematic review provided a better understanding of the development of mother-baby cohorts in China.

STUDY DESIGN

Systematic review.

METHODS

We conducted a systematic review for research or profile papers in English/Chinese that reported data from mother-baby cohorts in mainland China, with ≥1y follow-up after birth. We identified 315 papers, corresponding to 31 cohorts from 19 provinces/megacities.

RESULTS

All cohorts started in 1999-2017 (21 after 2010) and were set up with broad objectives or specific scientific focus. The baseline sample size varied, from <500 to >300,000 mothers. A majority of cohorts were initiated during pregnancy and followed children to <10y, only six to adolescence and none into adulthood. These cohorts mostly collected samples from mothers and babies, in addition to using interviews/questionnaires to collect information about pregnancy, birth and child health. Most cohorts were recruited from a single province/city. The large western region was understudied.

CONCLUSIONS

Mother-baby cohorts have developed rapidly in China, but usually with a short follow-up duration. Extending the follow-up of children and developing cross-cohort collaboration will increase the diversity, size and coverage of the sample, allow studying early influences on life-course health and identify targets for early intervention in the Chinese population.

Self-perceptions as mechanisms of achievement inequality: evidence across 70 countries

Children from lower socioeconomic status (SES) backgrounds tend to have more negative self-perceptions. More negative self-perceptions are often related to lower academic achievement. Linking these findings, we asked: Do children's self-perceptions help explain socioeconomic disparities in academic achievement around the world? We addressed this question using data from the 2018 Programme for International Student Assessment (PISA) survey, including n = 520,729 records of 15-year-old students from 70 countries. We studied five self-perceptions (self-perceived competency, self-efficacy, growth mindset, sense of belonging, and fear of failure) and assessed academic achievement in terms of reading achievement. As predicted, across countries, children's self-perceptions jointly and separately partially mediated the association between socioeconomic status and reading achievement, explaining additional 11% (ΔR2 = 0.105) of the variance in reading achievement. The positive mediation effect of self-perceived competency was more pronounced in countries with higher social mobility, indicating the importance of environments that "afford" the use of beneficial self-perceptions. While the results tentatively suggest self-perceptions, in general, to be an important lever to address inequality, interventions targeting self-perceived competency might be particularly effective in counteracting educational inequalities in countries with higher social mobility.

Childhood adversity during the post-apartheid transition and COVID-19 stress independently predict adult PTSD risk in urban South Africa: A biocultural analysis of the stress sensitization hypothesis

OBJECTIVES

The COVID-19 pandemic in South Africa introduced new societal adversities and mental health threats in a country where one in three individuals are expected to develop a psychiatric condition sometime in their life. Scientists have suggested that psychosocial stress and trauma during childhood may increase one's vulnerability to the mental health consequences of future stressors-a process known as stress sensitization. This prospective analysis assessed whether childhood adversity experienced among South African children across the first 18 years of life, coinciding with the post-apartheid transition, exacerbates the mental health impacts of psychosocial stress experienced during the 2019 coronavirus (COVID-19) pandemic (ca. 2020-2021).

MATERIALS AND METHODS

Data came from 88 adults who participated in a follow-up study of a longitudinal birth cohort study in Soweto, South Africa. Childhood adversity and COVID-19 psychosocial stress were assessed as primary predictors of adult PTSD risk, and an interaction term between childhood adversity and COVID-19 stress was calculated to evaluate the potential effect of stress sensitization.

RESULTS

Fifty-six percent of adults exhibited moderate-to-severe PTSD symptoms. Greater childhood adversity and higher COVID-19 psychosocial stress independently predicted worse post-traumatic stress disorder symptoms in adults. Adults who reported greater childhood adversity exhibited non-significantly worse PTSD symptoms from COVID-19 psychosocial stress.

DISCUSSION

These results highlight the deleterious mental health effects of both childhood trauma and COVID-19 psychosocial stress in our sample and emphasize the need for greater and more accessible mental health support as the pandemic progresses in South Africa.

Growth in Infancy and Childhood and Age at Menarche in Five Low- or Middle-Income Countries: Consortium of Health Orientated Research in Transitional Societies (COHORTS)

BACKGROUND

Earlier age at menarche is associated with behavioral and noncommunicable disease risks. The influence of birth weight (BW) (intrauterine) and postnatal growth on age at menarche is not well studied in low- and middle-income countries (LMICs).

OBJECTIVE

Therefore, we investigated these associations in 5 LMIC birth cohorts.

METHODS

We analyzed data from Brazil, Guatemala, India, the Philippines, and South Africa (n = 3983). We derived stunting (< -2 SD scores) at 24 mo using the WHO child growth standards. We generated interaction terms with categorized BW and conditional weight (lighter < 0 or heavier ≥ 0), and height (shorter < 0 or taller ≥ 0) z-scores. We categorized early-, modal-, and late-onset menarche and used multilevel ordinal regression. We used multilevel linear regression on continuous age at menarche.

RESULTS

Mean age at menarche was 12.8 y (95% CI: 12.7 12.9). BW was not associated with age at menarche. Conditional height at 24 mo and mid-childhood (OR: 1.35; 95% CI: 1.27, 1.44 and 1.32; 1.25, 1.41, respectively) and conditional weight at 24 mo and mid-childhood (OR: 1.15; 1.08, 1.22 and 1.18; 1.11, 1.25, respectively) were associated with increased likelihood of early-onset menarche. Being heavier at birth and taller at 24 mo was associated with a 4-mo (95% CI: 0.8, 7.6) earlier age at menarche than being lighter at birth and shorter at 24 mo. Being heavier at birth but lighter in mid-childhood was associated with a 3-mo (95% CI: 0.8, 4.8) later age at menarche than being lighter at birth and mid-childhood. Age at menarche was 7 mo later in stunted than nonstunted girls.

CONCLUSION

Age at menarche is inversely related to relative weight gain but also to rapid linear growth among those born shorter but remained stunted, and those born taller and grew excessively. These findings do not deter the global health goal to reduce growth faltering but emphasize the potential adverse effects of an obesogenic environment on adolescent development.

Contrasting speed and accuracy approaches to measure executive functions in three low-and middle-income countries

Executive functions (EF) can be measured by tests assessing accuracy, reaction times and by computing scores which combine these two components. Interpretation issues can arise from the use of different scoring methods across studies. Given that EF measures and their scoring methods are predominantly developed and validated in high income countries, little is known about the generalisability of such methods cross- culturally. The current paper compares two different established scoring approaches for measures of inhibition and cognitive flexibility: difference scores (which utilise reaction time only) and computed scores (combining accuracy and reaction time). We utilised data collected in adulthood from three low- and middle-income birth cohorts (Guatemala, Philippines, South Africa). Non-normal distributions were observed for both scoring methods in all three samples; however, this was more pronounced for the difference score method. Differing distribution patterns were observed across the three cohorts, which was especially evident in the Guatemala cohort, highlighting potential issues with using these methods across diverse populations. The data suggest that the computed scores may be a reliable measure of EF. However, the different ways of scoring and interpreting EF instruments need to be considered carefully for each population before use.

Prevalence and associated risk factors for elevated blood pressure in young adults in South Africa

BACKGROUND

Sub-Saharan Africa has been shown to have a high prevalence of hypertension (58% in rural black South Africans) with an accelerated course ending in end-stage renal disease. We sought to determine whether the prevalence of elevated blood pressure (EBP) in early adulthood was associated with any risk factors and/or renal target-organ damage in young adulthood, which could prevent development of these cardiorenal sequelae.

METHODS

Data including risk factors for hypertension and markers of kidney damage were collected from young adults (n = 933; age 28 years; 52% female) participating in the Birth to Twenty Plus (BT20) cohort in Soweto, South Africa. Blood pressure was measured on one occasion.

RESULTS

Fifty-four per cent of the study sample had EBP with more men affected (62%) than women (47%) (p < 0.001). Body mass index (BMI), hyperuricaemia and albuminuria had significant associations with EBP in men. In women, BMI, hyperuricaemia and a self-reported history of gestational hypertension had significant associations.

CONCLUSIONS

Our findings suggest that the pathophysiology of EBP in young adults differs between the genders and highlights a number of modifiable factors in its development.

The association between the timing, intensity and magnitude of adolescent growth and body composition in early adulthood

OBJECTIVES

There's paucity of longitudinal studies assessing the role of adolescent growth on adult body composition in developing countries. The aims of this study were to assess the association between adolescent change in height, weight and BMI and early adult height, weight, body fat and lean mass.

METHODS

Magnitude, timing and intensity of height, weight and BMI growth were modelled for participants from the Birth to Thirty (Bt30) cohort (7-23 years). Early adult height, weight, BMI and DXA-derived body composition were obtained 1881 black participants (21-24 years). Linear regression analyses were used to assess associations.

RESULTS

Adolescents with an earlier onset of puberty were heavier in childhood and had an earlier timing and faster weight gain velocity in late adolescence. The intensity of adolescent weight gain was positively associated with adult BMI and fat mass index (FMI) in females. Early timing of adolescent BMI gain was associated with increased weight and BMI in adult females and FMI in adult males. Achieving peak weight velocity around age at peak height velocity was associated with lower BMI and fat mass in both sexes.

CONCLUSION

This study confirms the adverse consequences of excessive weight gain prior to puberty, which is associated with an earlier and faster resurgence in weight gain velocity in early adulthood. Factors that contribute to an asynchronous timing of ages of peak weight and peak height velocities may accentuate the risk of adult obesity.

A comparison of paediatric hypertension clinical practice guidelines and their ability to predict adult hypertension in an African birth cohort

It remains unclear which paediatric hypertension clinical practice guideline (CPG) should be applied in an African population. We, therefore, aimed to compare commonly used CPG (2017 AAP, 2016 ESH, 2004 Fourth Report) developed in high-income countries for use in South African children at four paediatric ages (children: 5 years, 8 years; adolescents: 13 years, 17 years) to determine which best predicts elevated blood pressure (BP) in adulthood (22 years, 28 years). Moreover, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for each specific paediatric CPG was calculated across the age points. The 2017 AAP definition identified more children and adolescents with hypertension when compared to the 2004 Fourth Report and 2016 ESH guidelines. In computed hazards ratios, ages 8 years to 17 years, all three paediatric CPG significantly predicted the risk of elevated BP in young adulthood (p ≤ 0.032). However, sensitivity to predict elevated BP at age 22 years for all CPG was generally low (17.0%-33.0%) with higher specificity (87.4%-93.1%). Sensitivity increased at age 28 years (51.4%-70.1%), while specificity decreased (52.8%-65.1%). Both PPV and NPV at both adult age points varied widely (17.9%-79.9% and 29.3%-92.5% respectively). The performance of these paediatric CPG in terms of AUC were not optimal at both adult age points, however, the 2017 AAP definition at age 17 years met an acceptable level of performance (AUC = 0.71). Our results, therefore, highlight the need for more research to examine if an African-specific CPG would better identify high-risk children to minimise their trajectory towards adult hypertension.

The Impact of Human Immunodeficiency Virus and Menopause on Bone Mineral Density: A Longitudinal Study of Urban-Dwelling South African Women

An estimated 25% of South African women live with human immunodeficiency virus (HIV). Antiretroviral therapy roll-out has improved life expectancy, so many more women now reach menopause. We aimed to quantify changes in bone mineral density (BMD) during the menopausal transition in urban-dwelling South African women with and without HIV and determine whether HIV infection modified the effect of menopause on BMD changes. A 5-year population-based longitudinal study recruited women aged 40-60 years residing in Soweto and collected demographic and clinical data, including HIV status, anthropometry, and BMD, at baseline and at 5-year follow-up. All women were staged as pre-, peri-, or postmenopausal at both time points. Multivariable linear regression assessed relationships and interactions between HIV infection, menopause, and change in BMD. At baseline, 450 women had mean age 49.5 (SD 5.7) years, 65 (14.4%) had HIV, and 140 (31.1%), 119 (26.4%), and 191 (42.4%) were pre-, peri-, and postmenopausal, respectively; 34/205 (13.6%) women ≥50 years had a total hip (TH) or lumbar spine (LS) T-score ≤ -2.5. At follow-up 38 (8.4%), 84 (18.7%), and 328 (72.9%) were pre-, peri-, and postmenopausal. Those with HIV at baseline lost more total body (TB) BMD (mean difference -0.013 [95% confidence interval -0.026, -0.001] g/cm2 , p = 0.040) and gained more weight 1.96 [0.32, 3.60] kg; p = 0.019 than HIV-uninfected women. After adjusting for age, baseline weight, weight change, and follow-up time, the transition from pre- to postmenopause was associated with greater TB BMD losses in women with HIV (-0.092 [-0.042, -0.142] g/cm2 ; p = 0.001) than without HIV (-0.038 [-0.016, -0.060] g/cm2 , p = 0.001; interaction p = 0.034). Similarly, in women who were postmenopausal at both time points, those with HIV lost more TB BMD (-0.070 [-0.031, -0.108], p = 0.001) than women without HIV (-0.036 [-0.015, -0.057], p = 0.001, interaction p = 0.049). Findings were consistent but weaker at the LS and TH. Menopause-related bone loss is greater in women with HIV, suggesting women with HIV may be at greater risk of osteoporotic fractures. HIV services should consider routine bone health assessment in midlife women as part of long-term HIV care delivery. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Diabetes care cascade and associated factors in 10 700 middle-aged adults in four sub-Saharan African countries: a cross-sectional study

OBJECTIVES

We investigated progression through the care cascade and associated factors for people with diabetes in sub-Saharan Africa to identify attrition stages that may be most appropriate for targeted intervention.

DESIGN

Cross-sectional study.

SETTING

Community-based study in four sub-Saharan African countries.

PARTICIPANTS

10 700 individuals, aged 40-60 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the diabetes cascade of care defined as the age-adjusted diabetes prevalence (self-report of diabetes, fasting plasma glucose (FPG) ≥7 mmol/L or random plasma glucose ≥11.1 mmol/L) and proportions of those who reported awareness of having diabetes, ever having received treatment for diabetes and those who achieved glycaemic control (FPG <7.2 mmol/L). Secondary outcome measures were factors associated with having diabetes and being aware of the diagnosis.

RESULTS

Diabetes prevalence was 5.5% (95% CI 4.4% to 6.5%). Approximately half of those with diabetes were aware (54%; 95% CI 50% to 58%); 73% (95% CI 67% to 79%) of aware individuals reported ever having received treatment. However, only 38% (95% CI 30% to 46%) of those ever having received treatment were adequately controlled. Increasing age (OR 1.1; 95% CI 1.0 to 1.1), urban residence (OR 2.3; 95% CI 1.6 to 3.5), hypertension (OR 1.9; 95% CI 1.5 to 2.4), family history of diabetes (OR 3.9; 95% CI 3.0 to 5.1) and measures of central adiposity were associated with higher odds of having diabetes. Increasing age (OR 1.1; 95% CI 1.0 to 1.1), semi-rural residence (OR 2.5; 95% CI 1.1 to 5.7), secondary education (OR 2.4; 95% CI 1.2 to 4.9), hypertension (OR 1.6; 95% CI 1.0 to 2.4) and known HIV positivity (OR 2.3; 95% CI 1.2 to 4.4) were associated with greater likelihood of awareness of having diabetes.

CONCLUSIONS

There is attrition at each stage of the diabetes care cascade in sub-Saharan Africa. Public health strategies should target improving diagnosis in high-risk individuals and intensifying therapy in individuals treated for diabetes.

Growth patterns in childhood and adolescence and adult body composition: a pooled analysis of birth cohort studies from five low and middle-income countries (COHORTS collaboration)

OBJECTIVE

We examined associations among serial measures of linear growth and relative weight with adult body composition.

DESIGN

Secondary data analysis of prospective birth cohort studies.

SETTINGS

Six birth cohorts from Brazil, Guatemala, India, the Philippines and South Africa.

PARTICIPANTS

4173 individuals followed from birth to ages 22-46 years with complete and valid weight and height at birth, infancy, childhood and adolescence, and body composition in adult life.

EXPOSURES

Birth weight and conditional size (standardised residuals of height representing linear growth and of relative weight representing weight increments independent of linear size) in infancy, childhood and adolescence.

PRIMARY OUTCOME MEASURES

Body mass index, fat mass index (FMI), fat-free mass index (FFMI), fat mass/fat-free mass ratio (FM/FFM), and waist circumference in young and mid-adulthood.

RESULTS

In pooled analyses, a higher birth weight and relative weight gains in infancy, childhood and adolescence were positively associated with all adult outcomes. Relative weight gains in childhood and adolescence were the strongest predictors of adult body composition (β (95% CI) among men: FMI (childhood: 0.41 (0.26 to 0.55); adolescence: 0.39 (0.27 to 0.50)), FFMI (childhood: 0.50 (0.34 to 0.66); adolescence: 0.43 (0.32 to 0.55)), FM/FFM (childhood: 0.31 (0.16 to 0.47); adolescence: 0.31 (0.19 to 0.43))). Among women, similar patterns were observed, but, effect sizes in adolescence were slightly stronger than in childhood. Conditional height in infancy was positively associated with FMI (men: 0.08 (0.03 to 0.14); women: 0.11 (0.07 to 0.16)). Conditional height in childhood was positively but weakly associated with women's adiposity. Site-specific and sex-stratified analyses showed consistency in the direction of estimates, although there were differences in their magnitude.

CONCLUSIONS

Prenatal and postnatal relative weight gains were positive predictors of larger body size and increased adiposity in adulthood. A faster linear growth in infancy was a significant but weak predictor of higher adult adiposity.

Physical Activity and Its Association With Body Mass Index: A Cross-Sectional Analysis in Middle-Aged Adults From 4 Sub-Saharan African Countries

BACKGROUND

This study aimed to explore association of self-reported physical activity domains of work, leisure, and transport-related physical activity and body mass index (BMI) in 9388 adult men and women from the Africa-Wits-INDEPTH partnership for Genomic (AWI-Gen) study in Africa. Africa-Wits-INDEPTH partnership for Genomic is a large, population-based cross-sectional cohort with participants from 6 sites from rural and urban areas in 4 sub-Saharan African countries.

METHODS

A sex-stratified meta-analysis of cross-sectional data from men and women aged 29-82 years was used to assess the association of physical activity with BMI.

RESULTS

Overall, meeting physical activity guidelines of at least 150 minutes per week was associated with 0.82 kg/m2 lower BMI in men (β = -0.80 kg/m2; 95% confidence interval [CI], -1.14 to -0.47) and 0.68 kg/m2 lower BMI in women (β = -0.68 kg/m2; 95% CI, -1.03 to -0.33). Sex and site-specific differences were observed in the associations between physical activity domains and BMI. Among those who met physical activity guidelines, there was an inverse association between transport-related physical activity and BMI in men from Nanoro (Burkina Faso) (β = -0.79 kg/m2; 95% CI, -1.25 to -0.33) as well as work-related physical activity and BMI in Navrongo men (Ghana) (β = -0.76 kg/m2; 95% CI, -1.25 to -0.27) and Nanoro women (β = -0.90 kg/m2; 95% CI, -1.44 to -0.36).

CONCLUSIONS

Physical activity may be an effective strategy to curb rising obesity in Africa. More studies are needed to assess the impact of sex and geographic location-specific physical activity interventions on obesity.

Maternal Education Potentially Moderates the MAOA uVNTR Effects on Externalizing Behavior in Black South African Children

Interactions between the MAOA uVNTR and rearing environment are suggested to influence the developmental manifestations of childhood internalizing and externalizing behavior. However, few studies in the MAOA literature have included continental African children, or focused on non-clinical samples. We explored the main and interactive effects of the MAOA uVNTR (high and low activity alleles) in Black South African male (n = 478) and female (n = 540) children who were part of the longitudinal Birth to Twenty Plus cohort. Historical data on birth weight, gestational age at delivery, socioeconomic status, and maternal education were combined with genotypic information and analyzed using regression modeling. We found no significant main effects for the MAOA uVNTR on childhood behavior in either sex. A significant interaction (p = .04) was identified between MAOA and maternal education, suggesting that externalizing behavior in boys carrying a low activity MAOA allele varied in direct proportion to the education levels of their mothers. However, the model fit failed to reach significance, possibly due to our inclusion of only non-clinical pre-pubertal males. No significant interactions were detected for female children. Our findings lend tentative credibility to the Environmental Sensitivity metaframework, which suggests that MAOA is an important plasticity factor in childhood development.

Early-life stature, preschool cognitive development, schooling attainment, and cognitive functioning in adulthood: a prospective study in four birth cohorts

BACKGROUND

Nutrition is important for growth and brain development and therefore cognitive ability. Growth faltering in early childhood, an important indicator of early adversity, is associated with poorer developmental outcomes, some into adulthood, but this association probably reflects early-life deprivation. We aimed to investigate the associations between early-life stature, child IQ, and adult IQ.

METHODS

In this cohort study, we used prospective longitudinal data collected in four birth cohorts from Brazil (born in 1993), Guatemala (born in 1969-77), the Philippines (born in 1983-84), and South Africa (born in 1990). Using multivariable linear models, we estimated the relative contributions of early-life stature, child IQ, and schooling (highest school year completed) to adult IQ, including interaction effects among the early-childhood measures and schooling.

FINDINGS

We included 2614 individuals in the analysis. Early-life stature was associated with adult IQ (range across eight site-by-sex groups -0·14 to 3·17 IQ points) and schooling (-0·05 to 0·77 years) per height-for-age Z-score. These associations were attenuated when controlling for child IQ (-0·86 to 1·72 for adult IQ and -0·5 to 0·60 for schooling). The association of early-life stature with adult IQ was further attenuated when controlling for schooling (-1·86 to 1·21). Child IQ was associated with adult IQ (range 3·91 to 10·02 points) and schooling (0·25 to 1·30 years) per SD of child IQ in all groups; these associations were unattenuated by the addition of early-life stature to the models. The interaction between schooling and child IQ, but not that between schooling and early-life stature, was positively associated with adult IQ across groups.

INTERPRETATION

The observed associations of early-life stature with adult IQ and schooling varied across cohorts and sexes and explained little variance in adult IQ beyond that explained by child IQ. These findings suggest that interventions targeted at growth for health and early development are important. Our results are consistent with the inference that improving long-term cognitive outcomes might require interventions that more specifically target early cognitive ability.

FUNDING

Bill & Melinda Gates Foundation.

Child development with the D-score: tuning instruments to unity

The chapter familiarises the reader with an intuitive yet powerful methodology to tune instruments to a common unit, presenting a fresh approach that expresses measurements made by different instruments on the D-score scale. As a result, the reader may compare D-scores between ages, children or cohorts. It shows how to exploit common developmental milestones to bridge instruments and cohorts; presents an analysis to obtain D-scores from 16 cohorts and 14 instruments; compares D-score age-distribution across populations from four continents; suggests an indicator for the United Nations Sustainable Development Goals; and defines developmentally-on-track.

Menopause is associated with bone loss, particularly at the distal radius, in black South African women: Findings from the Study of Women Entering and in Endocrine Transition (SWEET)

Menopause transition is associated with accelerated bone loss, though data are limited from sub-Saharan African (SSA). Our objective was to describe bone density, geometry and estimated strength in women by menopause status and to explore whether patterns differed within those living with HIV.

METHODS

Radius and tibia peripheral QCT data were collected for Black South African women (n = 430) aged 40-61 years with verified menopause and HIV status. pQCT outcomes were distal 4 % radius and tibia total cross-sectional area (CSA), total volumetric bone mineral density (vBMD), and compressive bone strength (BSIc); proximal 66 % radius and 38 % tibia cortical vBMD, total CSA, cortical thickness, and Stress-strain Index (SSI). Linear regression assessed associations between pre, peri-, and postmenopausal groups and pQCT outcomes adjusting for age, height, and weight, and then stratified by HIV status. Mean [95%CI] and tests for trend (p-trend) across menopausal groups are presented.

RESULTS

Women were mean (SD) age 49.2 (5.3) years, with a body mass index (BMI) of 32.4 (6.3) m/kg², and 18 % were living with HIV. After adjustment, later menopause stage was associated with lower 4 % radius total mean [95%CIs] vBMD (premenopause: 345.7 [335.8,355.5] vs. postmenopause: 330.1 [322.7,337.6] mg/cm³, p-trend = 0.017) and BSIc (premenopause: 0.39 [0.37,0.41] vs. postmenopause: 0.36 [0.35,0.37] g²/cm⁴; p-trend = 0.012). Similar trends were observed at the 66 % radius for cortical vBMD (premenopause: 1146.8 [1138.9,1154.6] vs. postmenopause: 1136.1 [1130.1,1142.0] mg/cm³; p-trend = 0.028) and cortical thickness (premenopause: 2.01 [1.95,2.06] vs. postmenopause: 1.93 [1.89,1.98] mm; p-trend = 0.036). After stratification by HIV status a similar patten was observed in women with HIV (cortical vBMD premenopause: 1152.9 [1128.5,1177.2] mg/cm³ vs. postmenopause: 1123.6 [1106.0,1141.2] mg/cm³, p-trend = 0.048). Total CSA varied little by menopause or HIV status at either radius sites; few differences were found at the tibia.

CONCLUSION

In black South African women, menopause is associated with lower bone density and strength at the distal radius, a common site of osteoporotic fracture, in addition to lower cortical density and thickness at the proximal radius. Although the sample size was small, following stratification by HIV, women living with HIV had evidence of lower cortical density across menopause stages, unlike those without HIV. These findings raise concern for the incidence of Colles' fractures in postmenopausal women in South Africa; longitudinal studies of fracture incidence and implications of living with HIV are required.

Association of Longitudinal Nutrient Patterns with Body Composition in Black Middle-Aged South African Women: A Five-Year Follow-Up Study

This study aimed to evaluate the association of longitudinal nutrient patterns with body composition in a cohort of 132 black South African middle-aged women over five years. Nutrient patterns were identified using principal component analysis at baseline and follow-up 5 years later. Associations between nutrient patterns and repeated body composition measures were evaluated using generalized estimating equations, before and after adjusting for baseline education and repeated measures of age, socio-economic status, physical activity and employment. The animal-driven nutrient pattern was associated with increases in repeated measures of visceral adipose tissue (VAT) (β coefficient, 5.79 [95% CI, 0.01-11.57] cm²), fat mass index (FMI) (0.47 [0.01-0.93] kg·m^-2) and lean mass index (LMI) (0.50 [0.18-1.17] kg·m^-2) (p < 0.05) after adjustment. Vitamin C, sugar, and potassium-driven nutrient pattern was associated with higher FMI (0.50 [0.12-0.88] kg·m^-2) and LMI (0.58 [0.07-1.10] kg·m^-2) before and after adjustment (p < 0.05). These findings suggest that dietary interventions to curb obesity in black middle-aged South African women should focus on attenuation of nutrient patterns centred on added sugar, animal fat and animal protein.

Obesity, hypertension, and tobacco use associated with left ventricular remodeling and hypertrophy in South African women: Birth to Twenty Plus Cohort

BACKGROUND

Left ventricular hypertrophy (LVH) is a marker of increased risk in developing future life-threatening cardiovascular disease (CVD), however, it is unclear how CVD risk factors, such as obesity, blood pressure (BP), and tobacco use, are associated with left ventricular (LV) remodeling and LVH in urban African populations. Therefore, we aimed to identify the prevalence of LVH as well as the health factors associated with LV remodeling and LVH, within black South African adult women and their pre-pubescent children.

METHODS

Black female adults (n = 123; age: 29-68 years) and their children (n = 64; age: 4-10; 55% female) were recruited from the Birth to Twenty Plus Cohort in Soweto, South Africa. Tobacco and alcohol use, physical activity, presence of diabetes mellitus, heart disease, and medication were self-reported. Height, weight, and blood pressure were measured in triplicate to determine the prevalence of obesity and hypertension respectively. Echocardiography was used to assess LV mass at end-diastole, based on linear measurements, and indexed to body surface area to determine LVH.

RESULTS

Hypertension and obesity prevalences were 35.8% and 59.3% for adults and 45.3% and 6.3% for children. Self-reported tobacco use in adults was 22.8%. LVH prevalence was 35.8% in adults (75% eccentric: 25% concentric), and 6.3% in children. Concentric remodeling was observed in 15.4% of adults, however, concentric remodeling was only found in one child. In adults, obesity [OR: 2.54 (1.07-6.02; p = 0.02)] and hypertension [3.39 (1.08-10.62; p = 0.04)] significantly increased the odds of LVH, specifically eccentric LVH, while concentric LVH was associated with self-reported tobacco use [OR: 4.58 (1.18-17.73; p = 0.03)]. Although no logistic regression was run within children, of the four children LVH, three had elevated blood pressure and the child with normal blood pressure was overweight.

CONCLUSIONS

The association between obesity, hypertension, tobacco use, and LVH in adults, and the 6% prevalence of LVH in children, calls for stronger public health efforts to control risk factors and monitor children who are at risk.

Child development at age 5 years: The effects of maternal education, socioeconomic status and early-life growth examined prospectively in a lowresource setting

Background. Deeper insight into relationships between social factors and early childhood growth and development is required, particularly in low-resource settings. Objectives. To determine (i) associations between early linear growth and child development at 5 years; and (ii) whether early childhood growth mediates relationships between maternal education, household socioeconomic status (SES) and subsequent child development. Methods. This study used data from the Birth to Twenty Plus study, a longitudinal South African birth cohort study. The study sample comprised 636 participants with complete data at all relevant time points for the analysis. Household SES and maternal education were measured during pregnancy and the first two years of life, and growth between birth and 4 years of age. Child development was assessed using the Revised Denver Pre-screening Developmental Questionnaire (R-DPDQ). Multivariable regression analyses were used to investigate the association between SES, maternal education, growth and child development, and structural equation modelling was used to analyse the mediation of growth. Results. In both sexes, higher birthweight and household SES were associated with higher R-DPDQ scores. Increased relative linear growth, particularly between 0 and 2 years, was associated with higher R-DPDQ scores among boys (β=0.82; 95% confidence interval (CI): 0.27 - 1.37) at age 5. Growth status but not SES mediated the association between maternal education and R-DPDQ scores. Conclusion. Child development at 5 years was independently associated with SES and birthweight. The negative effects of lower maternal education on child development was attenuated by better growth.

A Mixed-Longitudinal Study of Height Velocity of Greek Schoolchildren and the Milestones of the Adolescent Growth Spurt

Height velocity (HV) growth charts constructed from longitudinal studies are scarce as they have inherent difficulties, e.g., time, and costs. These difficulties can be partly overcome by a mixed-longitudinal study that covers the entire age range within 3–6 years. To construct HV charts of Greek children and to estimate the milestones of the adolescent growth spurt (AGS), i.e., the onset of AGS (take-off), peak HV, and total pubertal growth (TPG), we performed a mixed longitudinal study in 1514 Greek schoolchildren (6–18 years) with height measurements every 6 months during three schoolyears. We constructed HV charts for boys and girls. Take-off occurs earlier in girls, and, in both sexes, it precedes by 1–1.5 years the appearance of physical signs of puberty. PHV in boys occurs at 12.61 years and in girls at 10.93 years. At take-off, boys are 5 cm taller than girls and TPG for boys is 35.8 cm and for girls 27.3 cm. We constructed HV charts plotted by age, irrespective of pubertal status, and presented data on the milestones of AGS. Furthermore, we suggest that the gradual increase in IGF-1 and E2 that occurs after 5 to 6 years of age triggers the onset of AGS, which precedes physical signs of puberty.

Blood pressure profile of primary school children in Eastern Cape province, South Africa: prevalence and risk factors

Abstract

Background

The problem of cardiovascular diseases and lack of adequate information about the blood pressure profiles among children in South Africa has enormous consequences for public health and the general well-being of communities.

Aim

The aim of this study is to determine the blood pressure profiles and associated risk factors of primary school children in South Africa.

Methods

A cross sectional study was conducted among 876 children aged 9 to 14 years from 18 randomly selected schools in the Eastern Cape province of South Africa. Standardised blood pressure measuring instruments were used and an average of three readings was considered. Blood pressure status was classified according to the percentiles of systolic blood pressure (SBP).

Results

The overall prevalence of hypertension was 5.2% and pre-hypertension was 18.5% while normal blood pressure was 76.3%. The multilevel binary logistic regression’s crude and adjusted analysis revealed that increase in age was significantly associated with elevated BP in children ([crude OR = 1.17 [1.05 – 1.29] and [adjusted OR = 1.12 [1.01 – 1.25]). In addition, increase in BMI was significantly associated with elevated BP in children ([crude OR = 1.08 [1.04 – 1.12] and [adjusted OR = 1.06 [1.02 – 1.11]). There was no statistically significant association between elevated BP and gender for both the univariate and multivariate models. There was also no statistical significant risk for elevated BP associated with place of residence.

Conclusions

In this sampled population the established proportion of primary school children with elevated BP is of great concern. In addition, older children and those with high BMI (that is, overweight/obesity) were associated with elevated BP. Interventions towards promoting healthy lifestyles among school learners is a necessity if we are to prevent cardiovascular diseases.

Childhood factors associated with suicidal ideation among South African youth: A 28-year longitudinal study of the Birth to Twenty Plus cohort

BACKGROUND

Although early life factors are associated with increased suicide risk in youth, there is a dearth of research on these associations for individuals growing up in disadvantaged socioeconomic contexts, particularly in low- and middle-income countries (LMICs). We documented the association between individual, familial, and environmental factors in childhood with suicidal ideation among South African youth.

METHODS AND FINDINGS

We used data from 2,020 participants in the Birth to Twenty Plus (Bt20+) study, a South African cohort following children born in Soweto, Johannesburg from birth (1990) to age 28 years (2018). Suicidal ideation was self-reported at ages 14, 17, 22, and 28 years, and the primary outcome of interest was suicidal ideation reported at any age. We assessed individual, familial, and socioeconomic characteristics at childbirth and during infancy, adverse childhood experiences (ACEs) between ages 5 and 13 years, and externalizing and internalizing problems between 5 and 10 years. We estimated odds ratios (ORs) of suicidal ideation for individuals exposed to selected childhood factors using logistic regression. Lifetime suicidal ideation was reported by 469 (23.2%) participants, with a 1.7:1 female/male ratio. Suicidal ideation rates peaked at age 17 and decreased thereafter. Socioeconomic adversity, low birth weight, higher birth order (i.e., increase in the order of birth in the family: first, second, third, fourth, or later born child), ACEs, and childhood externalizing problems were associated with suicidal ideation, differently patterned among males and females. Socioeconomic adversity (OR 1.13, CI 1.01 to 1.27, P = 0.031) was significantly associated with suicidal ideation among males only, while birth weight (OR 1.20, CI 1.02 to 1.41, P = 0.03), ACEs (OR 1.11, CI 1.01 to 1.21, P = 0.030), and higher birth order (OR 1.15, CI 1.07 to 1.243, P < 0.001) were significantly associated with suicidal ideation among females only. Externalizing problems in childhood were significantly associated with suicidal ideation among both males (OR 1.23, 1.08 to 1.40, P = 0.002) and females (OR 1.16, CI 1.03 to 1.30, P = 0.011). Main limitations of the study are the high attrition rate (62% of the original sample was included in this analysis) and the heterogeneity in the measurements of suicidal ideation.

CONCLUSIONS

In this study from South Africa, we observed that early life social and environmental adversities as well as childhood externalizing problems are associated with increased risk of suicidal ideation during adolescence and early adulthood.

Short- and long-read metagenomics of urban and rural South African gut microbiomes reveal a transitional composition and undescribed taxa

Human gut microbiome research focuses on populations living in high-income countries and to a lesser extent, non-urban agriculturalist and hunter-gatherer societies. The scarcity of research between these extremes limits our understanding of how the gut microbiota relates to health and disease in the majority of the world's population. Here, we evaluate gut microbiome composition in transitioning South African populations using short- and long-read sequencing. We analyze stool from adult females living in rural Bushbuckridge (n = 118) or urban Soweto (n = 51) and find that these microbiomes are taxonomically intermediate between those of individuals living in high-income countries and traditional communities. We demonstrate that reference collections are incomplete for characterizing microbiomes of individuals living outside high-income countries, yielding artificially low beta diversity measurements, and generate complete genomes of undescribed taxa, including Treponema, Lentisphaerae, and Succinatimonas. Our results suggest that the gut microbiome of South Africans does not conform to a simple "western-nonwestern" axis and contains undescribed microbial diversity.

Genetic associations with carotid intima-media thickness link to atherosclerosis with sex-specific effects in sub-Saharan Africans

Atherosclerosis precedes the onset of clinical manifestations of cardiovascular diseases (CVDs). We used carotid intima-media thickness (cIMT) to investigate genetic susceptibility to atherosclerosis in 7894 unrelated adults (3963 women, 3931 men; 40 to 60 years) resident in four sub-Saharan African countries. cIMT was measured by ultrasound and genotyping was performed on the H3Africa SNP Array. Two new African-specific genome-wide significant loci for mean-max cIMT, SIRPA (p = 4.7E-08), and FBXL17 (p = 2.5E-08), were identified. Sex-stratified analysis revealed associations with one male-specific locus, SNX29 (p = 6.3E-09), and two female-specific loci, LARP6 (p = 2.4E-09) and PROK1 (p = 1.0E-08). We replicate previous cIMT associations with different lead SNPs in linkage disequilibrium with SNPs primarily identified in European populations. Our study find significant enrichment for genes involved in oestrogen response from female-specific signals. The genes identified show biological relevance to atherosclerosis and/or CVDs, sex-differences and transferability of signals from non-African studies.

The Long-Term Health and Human Capital Consequences of Adverse Childhood Experiences in the Birth to Thirty Cohort: Single, Cumulative, and Clustered Adversity

Human capital—that is the cumulative abilities, education, social skills, and mental and physical health one possesses—is increasingly recognized as key to the reduction of inequality in societies. Adverse childhood experiences have been linked to a range of human capital indicators, with the majority of research in high-income, western settings. This study aims to examine the link between adverse childhood experiences and adult human capital in a South African birth cohort and to test whether associations differ by measurement of adversity. Secondary analysis of data from the Birth to Thirty study was undertaken. Exposure data on adversity was collected prospectively throughout childhood and retrospectively at age 22. Human capital outcomes were collected at age 28. Adversity was measured as single adverse experiences, cumulative adversity, and clustered adversity. All three measurements of adversity were linked to poor human capital outcomes, with risk for poor human capital increasing with the accumulation of adversity. Adversity was clustered by quantity (low versus high) and type (household dysfunction versus abuse). Adversity in childhood was linked to a broad range of negative outcomes in young adulthood regardless of how it was measured. Nevertheless, issues of measurement are important to understand the risk mechanisms that underlie the association between adversity and poor human capital.

Subjective social status is associated with happiness but not weight status or psychological distress: An analysis of three prospective birth cohorts from low- and middle-income countries

BACKGROUND

Subjective social status (SSS, perception of social position relative to a frame of reference) has been associated with physical, mental and socio-emotional wellbeing. However, these associations may be susceptible to unmeasured confounding by life course objective socio-economic position (SEP; such as wealth, education and employment) and life satisfaction.

PURPOSE

To estimate the association of position on ladders of perceived community respect and perceived economic status with weight, distress and wellbeing, independent of objective SEP in cohorts from three low and middle-income countries.

METHODS

We used data from birth cohorts in Guatemala (n = 1258), Philippines (n = 1323) and South Africa (n = 1393). We estimated the association of perceived community respect and perceived economic status with body mass index (kg/m²), the World Health Organization's Self-Reported Questionnaire-20 (SRQ-20) for psychological distress, and Lyubomirsky's Subjective Happiness Scale. We estimated these associations using robust linear regression models adjusting for indicators of life course objective SEP, early life characteristics, adult covariates, and life satisfaction.

RESULTS

Participants in South Africa (age 27-28y) rated themselves higher on average for both the respect (7 vs 5 in Guatemala and 6 in Philippines) and economic (5 vs 3 in Guatemala and 4 in Philippines) ladder measures. Position on neither community respect nor economic ladders were associated with BMI or psychological distress. Higher position on community respect (Guatemala: 0.03, 95%CI: 0.01, 0.04; Philippines: 0.03, 95% CI: 0.02, 0.05; South Africa: 0.07, 95%CI: 0.04, 0.09) and economic (Guatemala: 0.02, 95%CI: 0, 0.04; Philippines: 0.04, 95%CI: 0.02, 0.07; South Africa: 0.07, 95%CI: 0.04, 0.10) ladders were associated with greater happiness.

CONCLUSIONS

Subjective social status showed small but consistent associations with happiness in birth cohorts independent of life-course SEP.

Pulse wave velocity in South African women and children: comparison between the Mobil-O-Graph and SphygmoCor XCEL devices

BACKGROUND

Carotid-femoral pulse wave velocity (PWV) is the gold-standard noninvasive measure of arterial stiffness. Data comparing tonometry-based devices such as the SphygmoCor XCEL to simpler brachial-cuff-based estimates of PWV, such as from the Mobil-O-Graph in African populations are sparse. We therefore aimed to compare PWV measured by the Mobil-O-Graph and the SphygmoCor XCEL device in a sample of South African women and children.

METHODS

Women (n = 85) 29 years [interquartile range (IQR): 29-69] and their children/grandchildren (n = 27) 7 years (IQR: 4-11) were recruited for PWV measurement with Mobil-O-Graph and SphygmoCor XCEL on the same day. Wilcoxon signed-rank test, regression analysis, spearman correlation and Bland-Altman plots were used for PWV comparison between devices.

RESULTS

For adults, the SphygmoCor XCEL device had a significantly higher PWV (7.3 m/s, IQR: 6.4-8.5) compared with the Mobil-O-Graph (5.9 m/s, IQR: 5.0-8.1, P = 0.001) with a correlation coefficient of 0.809 (P ≤ 0.001). Bland--Altman analysis indicated an acceptable level of agreement but significant bias (mean difference PWV: 0.90 ± 1.02 m/s; limits of agreement: -1.10 to 2.90). The odds of having a PWV difference more than 1 m/s decreased with a higher age [odds ratio (OR): 0.95, 95% confidence interval (95% CI) = 0.92-0.98] and increased with greater height (OR: 1.10, 95% CI = 1.01-1.21, P = 0.03) in multivariable analysis. In children, the Bland-Altman indicated an excellent level of agreement (-0.03 ± 0.63 m/s; limits of agreement: -1.26 to 1.21), but no correlation was found (rs = 0.08, P = 0.71).

CONCLUSION

Particularly in younger and taller women, the Mobil-O-Graph significantly underestimated PWV compared with the SphygmoCor. Although no correlation was found between the two devices for children, further research is required due to the small sample size. Furthermore, the clinical value of both methods in young African populations requires further investigation.

Changes in asset-based wealth across the life course in birth cohorts from five low- and middle-income countries

Background

Temporally-harmonized asset-based measures of wealth can be used to study the association of life-course wealth exposures in the same scale with health outcomes in low- and middle-income countries (LMICs). The within-individual longitudinal stability of asset-based indices of wealth in LMICs is poorly understood.

Methods

Using data from five birth cohorts from three continents, we developed temporally-harmonized asset indices over the life course through polychoric principal component analysis of a common set of assets collected consistently over time (18 years in Brazil to 50 years in Guatemala). For each cohort, we compared the harmonized index to cross-sectional indices created using more comprehensive asset measures using rank correlations. We evaluated the rank correlation of the harmonized index in early life and adulthood with maternal schooling and own attained schooling, respectively.

Results

Temporally-harmonized asset indices developed from a consistently-collected set of assets (range: 10 in South Africa to 30 in Philippines) suggested that mean wealth improved over time for all birth cohorts. Cross-sectional indices created separately for each study wave were correlated with the harmonized index for all cohorts (Brazil: r = 0.78 to 0.96; Guatemala: r = 0.81 to 0.95; India: 0.75 to 0.93; Philippines: r = 0.92 to 0.99; South Africa: r = 0.84 to 0.96). Maternal schooling (r = 0.15 to 0.56) and attained schooling (r = 0.23 to 0.53) were positively correlated with the harmonized asset index in childhood and adulthood respectively.

Conclusions

Temporally-harmonized asset indices displayed coherence with cross-sectional indices as well as construct validity with schooling.

•

Temporally-harmonized asset indices are useful to assess relative importance of wealth at different life stages with health on the same scale.

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Harmonized indices using a subset of assets were correlated with cross-sectional asset indices using all available assets in five LMIC birth cohorts.

•

Harmonized indices displayed construct validity, as demonstrated by its correlation with schooling.

•

Harmonized indices were robust to alternate specifications such as shorter lists of assets, study years, and factor extraction procedures.

Innovative methods to analyse the impact of gender norms on adolescent health using global health survey data

Background

Understanding how gender norms affect health is an important entry point into designing programs and policies to change norms and improve gender equality and health. However, it is rare for global health datasets to include questions on gender norms, especially questions that go beyond measuring gender-related attitudes, thus limiting gender analysis.

Methods

We developed five case studies using health survey data from six countries to demonstrate approaches to defining and operationalising proxy measures and analytic approaches to investigating how gender norms can affect health. Key findings, strengths and limitations of our norms proxies and methodological choices are summarised.

Findings

Case studies revealed links between gender norms and multiple adolescent health outcomes. Proxys for norms were derived from data on attitudes, beliefs, and behaviours, as well as differences between attitudes and behaviours. Data were cross-sectional, longitudinal, census- and social network-based. Analytic methods were diverse. We found that gender norms affect: 1) Intimate partner violence in Nigeria; 2) Unhealthy weight control behaviours in Brazil and South Africa; 3) HIV status in Zambia; 4) Health and social mobility in the US; and 5) Childbirth in Honduras.

Interpretation

Researchers can use existing global health survey data to examine pathways through which gender norms affect health by generating proxies for gender norms. While direct measures of gender norms can greatly improve the understanding of how gender affects health, proxy measures for norms can be designed for the specific health-related outcome and normative context, for instance by either aggregating behaviours or attitudes or quantifying the difference (dissonance) between them. These norm proxies enable evaluations of the influence of gender norms on health and insights into possible reference groups and sanctions for non-compliers, thus informing programmes and policies to shape norms and improve health.

•

This article presents effective methods to study gender norms in existing global health survey data.

•

We devised conceptual pathways linking gender norms to gender-based health disparities.

•

We identified gender norms proxies and reference groups enforcing the norm.

•

We tested hypotheses linking gender norms to health.

•

These methods can aid policy and programme design to advance gender equality and health.

QANOVA: quantile-based permutation methods for general factorial designs

Population means and standard deviations are the most common estimands to quantify effects in factorial layouts. In fact, most statistical procedures in such designs are built toward inferring means or contrasts thereof. For more robust analyses, we consider the population median, the interquartile range (IQR) and more general quantile combinations as estimands in which we formulate null hypotheses and calculate compatible confidence regions. Based upon simultaneous multivariate central limit theorems and corresponding resampling results, we derive asymptotically correct procedures in general, potentially heteroscedastic, factorial designs with univariate endpoints. Special cases cover robust tests for the population median or the IQR in arbitrary crossed one-, two- and higher-way layouts with potentially heteroscedastic error distributions. In extensive simulations, we analyze their small sample properties and also conduct an illustrating data analysis comparing children’s height and weight from different countries.

Adolescent Mental Health Problems and Adult Human Capital: Findings From the South African Birth to Twenty Plus Cohort at 28 Years of Age

PURPOSE

We investigated associations between adolescent internalizing and externalizing problems and adult human capital in a non-Western setting. Little is known about adolescent mental health problems and adult outcomes in low- and middle-income countries, many of which are characterized by high levels of adversities.

METHODS

Data came from the Birth to Twenty Plus cohort, started in Soweto, Johannesburg, South Africa, in 1990. We estimated associations of internalizing and externalizing problems at the age of 14 years with self-reported educational, employment, welfare receipt, psychosocial (psychological distress, criminality, substance use), interpersonal (social isolation, intimate partner violence, partnership status), and HIV outcomes at the age of 28 years.

RESULTS

Adolescents with high internalizing problems were less likely to have completed secondary school or be formally employed and more likely to report psychological distress. Those with high levels of externalizing problems were more likely to report adulthood criminal activity and substance use. We found significant associations between internalizing and externalizing problems and intimate partner violence. There was no association between adolescent mental health problems and welfare receipt, HIV, social isolation, or partnership status. Men were more likely to report incomplete secondary education, no formal employment, criminality and substance use, social isolation, and no serious relationship, whereas women were more likely to experience psychological distress and be in receipt of welfare.

CONCLUSIONS

Adolescent mental health problems are associated with long-term negative adult functioning under varying socioeconomic conditions. Interventions to recognize and address youth mental health problems in low- and middle-income countries are needed to avert serious adverse adult and societal consequences.

Secondary analysis of retrospective and prospective reports of adverse childhood experiences and mental health in young adulthood: Filtered through recent stressors

BACKGROUND

Evidence has identified the detrimental effects that adverse childhood experiences (ACEs) have on outcomes across the life course. We assess associations between prospective and retrospective ACEs and mental health in young adulthood and the influence of recent stressors.

METHODS

Secondary analysis of a sample of 1592 young adults from the Birth to Twenty Plus cohort, from 1990 to 2013, were assessed throughout their first 18 years for prospective ACEs. Retrospective ACEs and an assessment of mental health were collected at the 22-23-year data point.

FINDINGS

Prospective physical and sexual abuse are associated with an increased risk of depression (OR 1·7 [95% CI 1·37-1·93, p = 0·034], and OR 1·8 [95% CI 1·27-2·07, p = 0·018], respectively). Retrospective emotional abuse/neglect is associated with increased anxiety (OR 1·8 [95% CI 1·32-2·36, p = 0·000]), depression (OR 1·6 [95% CI 1·08-2·25, p = 0·018]) and overall psychological distress (OR 1·6 [95% CI 1·18-2·17, p = 0·002]). Prospectively reporting four or more ACEs is associated with a twofold increase in risk for overall psychological distress (OR 2·2 [95% CI 1·58-3.12, p = 0·008]). Retrospectively reporting four or more ACEs is associated with increased likelihood of somatization (p = 0·004), anxiety (p = 0·002), depression (p = 0·021), and overall psychological distress (p = 0·005).

INTERPRETATION

Both individual and combined retrospective and prospective ACEs are related to mental health in young adulthood. Recent stressors reinforce this relationship; the likelihood of those who report more ACEs experiencing psychological distress increases when adjusting for recent stressors.

FUNDING

Wellcome Trust (UK), South African Medical Research Council, Human Sciences Research Council, University of the Witwatersrand and supported by the DSI-NRF Centre of Excellence in Human Development.

Digital Mega-Studies as a New Research Paradigm: Governing the Health Research of the Future

'Digital Mega-Studies' are entirely or extensively digitised, longitudinal, population-scale initiatives, collecting, storing, and making available individual-level research data of different types and from multiple sources, shaped by technological developments and unforeseeable risks over time. The Australian 'Gen V' project exemplifies this new research paradigm. In 2019, we undertook a multidisciplinary, multi-stakeholder process to map Digital Mega-Studies' key characteristics, legal and governance challenges and likely solutions. We conducted large and small group processes within a one-day symposium and directed online synthesis and group prioritisation over subsequent weeks. We present our methods (including elicitation, affinity mapping and prioritisation processes) and findings, proposing six priority governance principles across three areas-data, participation, trust-to support future high-quality, large-scale digital research in health.

Associations Between CYP17A1 and SERPINA6/A1 Polymorphisms, and Cardiometabolic Risk Factors in Black South Africans

Research in European and Asian populations has reported associations between single nucleotide polymorphisms (SNPs) in CYP17A1 and SERPINA6/A1 and circulating glucocorticoid concentrations, and some key cardiometabolic risk factors. This study aimed to investigate these associations in black South African adults, who are disproportionally affected by the metabolic syndrome and its related cardiometabolic risk factors. The dataset included black South African adults (n = 4,431; 56.7% women) from the AWI-Gen study, genotyped on the H3A genotyping array and imputed using the African reference panel at the Sanger imputation service. From the imputed data, 31 CYP17A1 SNPs and 550 SERPINA6/A1 SNPs were extracted. The metabolic syndrome and its components were defined using the 2009 harmonized guidelines. Serum glucocorticoid concentrations were measured in a subset of 304 men and 573 women, using a liquid chromatography-mass spectrometry method. Genetic associations were detected using PLINK. Bonferroni correction was used to control for multiple testing. A SNP at SERPINA6/A1, rs17090691 (effect allele G), was associated with higher diastolic blood pressure (BP) in all adults combined (p = 9.47 × 10-6). Sex-stratified analyses demonstrated an association between rs1051052 (effect allele G), another SERPINA6/A1 SNP, and higher high-density lipoprotein (HDL) cholesterol concentrations in women (p = 1.23 × 10-5). No association was observed between these variants and glucocorticoids or between any of the CYP17A1 SNPs and metabolic outcomes after adjusting for multiple testing. Furthermore, there were no associations between any of the SNPs tested and the metabolic syndrome. This study reports novel genetic associations between two SNPs at SERPINA6/A1 and key cardiometabolic risk factors in black South Africans. Future replication and functional studies in larger populations are required to confirm the role of the identified SNPs in the metabolic syndrome and assess if these associations are mediated by circulating glucocorticoids.

Analysis of Maternal Postnatal Depression, Socioeconomic Factors, and Offspring Internalizing Symptoms in a Longitudinal Cohort in South Africa

IMPORTANCE

Few studies from low-and-middle income countries have investigated long-term associations between maternal postnatal depression and offspring internalizing (ie, depressive and anxiety) symptoms, and none have investigated interactions in this association.

OBJECTIVE

To investigate the association between maternal postnatal depression and offspring internalizing symptoms from adolescence to adulthood and the interaction with exposure to socioeconomic adversity and with the child's sex.

DESIGN, SETTING, AND PARTICIPANTS

This secondary analysis used data from Birth to Twenty Plus (BT20+), a prospective birth cohort study of children born in Soweto, South Africa, and followed up until age 28 years. Data were collected from 1990 to 2018, and data were analyzed for this study from February 16 through December 15, 2020.

EXPOSURES

Maternal postnatal depression self-reported by mothers 6 months after childbirth.

MAIN OUTCOMES AND MEASURES

The main outcome was offspring internalizing symptoms, assessed at offspring ages 14 years, 22 years, and 28 years and modeled longitudinally. Participants with the highest probability of experiencing high internalizing symptoms (ie, those in the top 20% of the distribution) from age 14 to 28 years were categorized as belonging to the high internalizing symptoms trajectory (vs the low trajectory). Socioeconomic adversity was measured with an index (continuous variable) including low maternal education, household crowding, low assets, and low maternal age. This variable was further stratified into more than 1 SD above the mean index, more than 1 SD below the mean index, and from 1 SD below to 1 SD above the mean index to conduct subgroup analyses. Associations were investigated using multivariable regression models.

RESULTS

Among 1087 participants born in Soweto, South Africa (543 [50.0%] male participants; 544 [50.0%] female participants), 118 individuals (10.8%) showed a high trajectory of internalizing symptoms from age 14 to 28 years vs 969 individuals (89.1%) with a low trajectory. Children exposed to maternal postnatal depression had statistically significantly increased odds of following the high trajectory (adjusted odds ratio [aOR] per 1-SD increase in maternal postnatal depression, 1.20; 95% CI, 1.02-1.41). This increase in odds differed by exposure to socioeconomic adversity and by child sex: for male participants, the increase in odds was greater in a context of higher vs lower socioeconomic adversity (eg, for >1 SD above the mean: aOR, 3.28; 95% CI, 1.06-10.14 vs for >1 SD below the mean: aOR, 0.98; 95% CI, 0.64-1.50; P for interaction = .12), while for female participants, the increase in odds was greater in a context of lower vs higher socioeconomic adversity (eg, for >1 SD below the mean: aOR, 1.82; 95 % CI, 1.12-2.98 vs for >1 SD above the mean: aOR, 0.59; 95 % CI, 0.30-1.17; P for interaction = .002) (P for 3-way interaction = .003).

CONCLUSIONS AND RELEVANCE

This study found that postnatal depression was associated with higher odds of persistently increased internalizing symptoms among offspring from adolescence to adulthood in a middle-income country, with variation by socioeconomic adversity and sex. These findings suggest that better understanding of these associations is needed to implement targeted interventions and maximize the impact of public health initiatives aimed at breaking the intergenerational transmission of mental health problems.

Glucocorticoids associate with cardiometabolic risk factors in black South Africans

Circulating glucocorticoids are associated with metabolic syndrome and related cardiometabolic risk factors in non-Africans. This study investigated these associations in Africans, whose metabolic phenotype reportedly differs from Europeans. Adiposity, blood pressure, glycaemia, insulin resistance, and lipid profile, were measured in 316 African men and 788 African women living in Soweto, Johannesburg. The 2009 harmonized criteria were used to define metabolic syndrome. Serum glucocorticoids were measured using liquid chromatography-mass spectrometry. Cortisol was associated with greater odds presenting with metabolic syndrome (odds ratio (95% CI) =1.50 (1.04, 2.17) and higher systolic (beta coefficient, β (95% CI) =0.04 (0.01, 0.08)) and diastolic (0.05 (0.02, 0.09)) blood pressure, but higher HDL (0.10 (0.02, 0.19)) and lower LDL (-0.14 (-0.24, -0.03)) cholesterol concentrations, in the combined sample of men and women. In contrast, corticosterone was only associated with higher insulin sensitivity (Matsuda index; 0.22 (0.03, 0.41)), but this was not independent of BMI. Sex-specific associations were observed, such that both cortisol and corticosterone were associated with higher fasting glucose (standardized β (95% CI): 0.24 (0.12, 0.36) for cortisol and 0.12 (0.01, 0.23) for corticosterone) and HbA1c (0.13 (0.01, 0.25) for cortisol and 0.12 (0.01, 0.24) for corticosterone) in men only, but lower HbA1c (0.10 (-0.20, -0.01) for cortisol and -0.09 (-0.18, -0.03) for corticosterone) in women only. Our study reports for the first time that associations between circulating glucocorticoid concentrations and key cardiometabolic risk factors exhibit both glucocorticoid- and sex-specificity in Africans.

The Chronic Kidney Disease in Africa (CKD-Africa) collaboration: lessons from a new pan-African network

Chronic kidney disease (CKD) is a global public health problem, seemingly affecting individuals from low-income and-middle-income countries (LMICs) disproportionately, especially in sub-Saharan Africa. Despite the growing evidence pointing to an increasing prevalence of CKD across Africa, there has not been an Africa-wide concerted effort to provide reliable estimates that could adequately inform health services planning and policy development to address the consequences of CKD. Therefore, we established the CKD in Africa (CKD-Africa) Collaboration. To date, the network has curated data from 39 studies conducted in 12 African countries, totalling 35 747 participants, of which most are from sub-Saharan Africa. We are, however, continuously seeking further collaborations with other groups who have suitable data to grow the network. Although many successful research consortia exist, few papers have been published (with none from Africa) detailing the challenges faced and lessons learnt in setting up and managing a research consortium. Drawing on our experience, we describe the steps taken and the key factors required to establish a functional collaborative consortium among researchers in Africa. In addition, we present the challenges we encountered in building our network, how we managed those challenges and the benefit of such a collaboration for Africa. Although the CKD-Africa Collaboration is focused primarily on CKD research, many of the lessons learnt can be applied more widely in public health research in LMICs.

Assessing sugar-sweetened beverage intakes, added sugar intakes and BMI before and after the implementation of a sugar-sweetened beverage tax in South Africa

OBJECTIVE

To provide insight into the context and public health implications of the South African sugar-sweetened beverage (SSB) tax (Health Promotion Levy; HPL) by describing SSB and added sugar intakes, as well as BMI, 1 year prior to, at the time of and 1 year after implementation of the HPL.

DESIGN

Longitudinal dietary intake was assessed using a quantitative food frequency questionnaire (QFFQ) and BMI was measured via anthropometry.

SETTING

Soweto, Johannesburg, South Africa.

PARTICIPANTS

Adolescents, young adults and middle-aged adults (n 617).

RESULTS

At baseline, median SSB intakes were 36 ml/d, 214 ml/d and 750 ml/d for those in low, medium and high consumption tertiles, respectively. SSB intake decreased by two times/week in medium consumers and seven times/week in high consumers between baseline and 12 months, equivalent to 107 ml/d and 536 ml/d reductions, respectively. These reduced levels were maintained in the following year (i.e. to 24 months). There was an overall decrease in the amount of energy consumed as added sugar in the low (-48 kJ/d), medium (-153 kJ/d) and high (-106 kJ/d) SSB consumption groups between baseline and 24 months; however, the percentage of total energy consumed as added sugar remained relatively consistent (between 10 and 11 %). There were small overall increases in BMI across low (0·6 kg/m2), medium (0·9 kg/m2) and high (1·0 kg/m2) SSB tertiles between baseline and 24 months.

CONCLUSIONS

These findings suggest reductions in SSB and added sugar consumption contemporaneous to the introduction of the HPL - particularly for those with higher baseline intakes.

Estimating the burden of cardiovascular risk in community dwellers over 40 years old in South Africa, Kenya, Burkina Faso and Ghana

Introduction

Cardiovascular disease (CVD) risk factors are increasing in sub-Saharan Africa. The impact of these risk factors on future CVD outcomes and burden is poorly understood. We examined the magnitude of modifiable risk factors, estimated future CVD risk and compared results between three commonly used 10-year CVD risk factor algorithms and their variants in four African countries.

Methods

In the Africa-Wits-INDEPTH partnership for Genomic studies (the AWI-Gen Study), 10 349 randomly sampled individuals aged 40–60 years from six sites participated in a survey, with blood pressure, blood glucose and lipid levels measured. Using these data, 10-year CVD risk estimates using Framingham, Globorisk and WHO-CVD and their office-based variants were generated. Differences in future CVD risk and results by algorithm are described using kappa and coefficients to examine agreement and correlations, respectively.

Results

The 10-year CVD risk across all participants in all sites varied from 2.6% (95% CI: 1.6% to 4.1%) using the WHO-CVD lab algorithm to 6.5% (95% CI: 3.7% to 11.4%) using the Framingham office algorithm, with substantial differences in risk between sites. The highest risk was in South African settings (in urban Soweto: 8.9% (IQR: 5.3–15.3)). Agreement between algorithms was low to moderate (kappa from 0.03 to 0.55) and correlations ranged between 0.28 and 0.70. Depending on the algorithm used, those at high risk (defined as risk of 10-year CVD event >20%) who were under treatment for a modifiable risk factor ranged from 19.2% to 33.9%, with substantial variation by both sex and site.

Conclusion

The African sites in this study are at different stages of an ongoing epidemiological transition as evidenced by both risk factor levels and estimated 10-year CVD risk. There is low correlation and disparate levels of population risk, predicted by different risk algorithms, within sites. Validating existing risk algorithms or designing context-specific 10-year CVD risk algorithms is essential for accurately defining population risk and targeting national policies and individual CVD treatment on the African continent.

Prevalence and socio-demographic correlates of tobacco and alcohol use in four sub-Saharan African countries: a cross-sectional study of middle-aged adults

BACKGROUND

Substance misuse is a global public health problem. In addition to social and economic concerns, consumption of tobacco and alcohol is associated with susceptibility to cardiovascular, respiratory, and infectious diseases, cancers, and risk of transition to substance use disorders. African data suggest regional differences in the prevalence and patterns of substance use, but a number of key questions remain. This cross-sectional population-based study of middle-aged adults aims to examine prevalence and socio-demographic correlates of substance use in four sub-Saharan African countries, in rural and urban settings.

METHODS

Participants aged between 40 and 60 years were recruited from six research centres as part of the Africa Wits-INDEPTH partnership for Genomic Research study. Data on patterns of tobacco and alcohol consumption was captured, and the latter further assessed using the CAGE (cut-annoyed-guilty-eye) questionnaire.

RESULTS

Data from 10,703 participants suggested that more men (68.4%) than women (33.3%) were current substance users. The prevalence of current smoking was significantly higher in men than in women (34.5% vs 2.1%, p < 0.001). Smokeless tobacco was used more by women than men (14.4% vs 5.3%, p < 0.001). Current smoking was associated with alcohol consumption in men, and smoking cessation in men was associated with being a former drinker, having higher socio-economic status, and if married or cohabiting. Current alcohol consumption was higher in men, compared to women (60.3% vs 29.3%), and highest in men from Soweto (70.8%) and women from Nanoro (59.8%). The overall prevalence of problematic alcohol consumption among men was 18.9%, and women 7.3%. Men were significantly more likely to develop problematic drinking patterns, and this was more common in those who were divorced or widowed, and in current smokers.

CONCLUSIONS

Regional variation in the patterns and prevalence of substance use was observed across study sites, and in rural and urban settings. The high levels of substance use recorded in this study are of concern due to the increased risk of associated morbidities. Further longitudinal data will be valuable in determining trends in substance misuse in Africa.

Child development with the D-score: tuning instruments to unity

The chapter familiarises the reader with an intuitive yet powerful methodology to tune instruments to a common unit, presenting a fresh approach that expresses measurements made by different instruments on the D-score scale. As a result, the reader may compare D-scores between ages, children or cohorts. It shows how to exploit common developmental milestones to bridge instruments and cohorts; presents an analysis to obtain D-scores from 16 cohorts and 14 instruments; compares D-score age-distribution across populations from four continents; suggests an indicator for the United Nations Sustainable Development Goals; and defines developmentally-on-track.

Influences of Differing Menarche Status on Motor Capabilities of Girls, 13 To 16 Years: A Two-Year Follow-Up Study

Puberty and the onset of menarche influences the motor performance of girls. However, the magnitude of these influences during varying maturity status, is not clear. This longitudinal study over two years aimed to investigate differences in motor fitness between early and late developing girls based on pre- and post-menarche status. A convenience sample (n = 58) of girls aged 13.51 ± 3.51, divided by means of the Status Quo method into pre (n = 13) and post-menarche (n = 45) groups, was used. Motor fitness was tested once annually by standardized protocols. Basic statistics, independent t-testing and a repeated measures ANOVA with a post hoc Bonferonni correction were used (p < 0.05 = statistical significance). Effect sizes were determined by Cohen's d-values. Only explosive upper body strength differed significantly between groups during baseline, favoring post-menarche girls. Initially, post-menarche girls showed advantages in hand-eye coordination and speed (p > 0.05) with pre-menarche girls performing better in agility and explosive leg strength (p > 0.05). At 15.51 years, no significant, between-group differences were found. Pre-menarche girls surpassed post-menarche girls in hand-eye coordination and 0-40 m speed and post-menarche girls displayed higher explosive leg and upper body strength scores (p > 0.05). Our data show that the potential to excel in sport based on motor capabilities can only be accurately estimated 1-2 years after reaching menarche.

Development and validation of the Soweto Stress Scale: Mixed-methods, population-based study of adults living in Soweto, South Africa

This article moves from ethnography to epidemiology to generate a locally specific assessment of stress and evaluates it correlates with general psychiatric morbidity. We conducted two related ethnographic studies of stress and distress in Soweto, South Africa (N=107). We then used these studies to develop the Soweto Stress Scale, piloted the scale, and then evaluated its use in an epidemiological surveillance study of stress and health (N=933). We used factor analyses to evaluate factor structure and maximum likelihood estimates to evaluate comparative fit indices. The Keiser-Meyer-Olkin test identified sufficient sample variation, and the scale was suitable for factor analysis. The confirmatory factor analysis supported a single-factor model with a χ²(df) (104) = 475.88; p < 0.001. Even though the comparative fit index/Tucker-Lewis index were poor and could not be improved, the Cronbach's alpha (0.81) was excellent, suggesting that the model was a reasonable representation of the data. The final model indicated that there was covariance between items and consistency with our theoretical concept of stress. The Soweto Stress Scale shows strong internal consistency and reflects a very localized view of social stressors and may serve to identify those with higher psychological morbidity. Given the racial, ethnic, and linguistic diversity within South Africa, our emic stress scale was tested in a community sample but may be useful for screening individuals with higher levels of stress or psychological distress within clinical settings.

Patterns of Growth in Childhood in Relation to Adult Schooling Attainment and Intelligence Quotient in 6 Birth Cohorts in Low- and Middle-Income Countries: Evidence from the Consortium of Health-Oriented Research in Transitioning Societies (COHORTS)

BACKGROUND

Growth faltering has been associated with poor intellectual performance. The relative strengths of associations between growth in early and in later childhood remain underexplored.

OBJECTIVES

We examined the association between growth in childhood and adult human capital in 5 low- and middle-income countries (LMICs).

METHODS

We analyzed data from 9503 participants in 6 prospective birth cohorts from 5 LMICs (Brazil, Guatemala, India, the Philippines, and South Africa). We used linear and quasi-Poisson regression models to assess the associations between measures of height and relative weight at 4 age intervals [birth, age ∼2 y, midchildhood (MC), adulthood] and 2 dimensions of adult human capital [schooling attainment and Intelligence Quotient (IQ)].

RESULTS

Meta-analysis of site- and sex-specific estimates showed statistically significant associations between size at birth and height at ∼2 y and the 2 outcomes (P < 0.001). Weight and length at birth and linear growth from birth to ∼2 y of age (1 z-score difference) were positively associated with schooling attainment (β: 0.13; 95% CI: 0.08, 0.19, β: 0.17; 95% CI: 0.07, 0.32, and β: 0.25, 95% CI: 0.10, 0.40, respectively) and adult IQ (β: 0.74, 95% CI: 0.35, 1.14, β: 0.73, 95% CI: 0.35, 1.10, and β: 1.52, 95% CI: 0.96, 2.08, respectively). Linear growth from age 2 y to MC and from MC to adulthood was not associated with higher school attainment or IQ. Change in relative weight in early childhood, MC, and adulthood was not associated with either outcome.

CONCLUSIONS

Linear growth in the first 1000 d is a predictor of schooling attainment and IQ in adulthood in LMICs. Linear growth in later periods was not associated with either of these outcomes. Changes in relative weight across the life course were not associated with schooling and IQ in adulthood.

Obesity and adiposity of 3- to 6-year-old children born to mothers with hyperglycaemia first detected in pregnancy in an urban South African setting

BACKGROUND

Understanding the association between maternal metabolic conditions in pregnancy and the risk of childhood overweight, a growing concern in sub-Saharan Africa (SSA), helps to identify opportunities for childhood obesity prevention.

AIM

To assess the association between hyperglycaemia first detected in pregnancy (HFDP) (gestational diabetes mellitus [GDM] and diabetes in pregnancy [DIP]) and child obesity and adiposity in pre-school-aged children in South Africa, independently of maternal BMI.

SUBJECTS AND METHODS

Measurement of anthropometry and fat mass index (FMI) by the deuterium dilution method was done for 102 3-6-year-old children born to mothers with HFDP and 102 HFDP-unexposed children. Hierarchical regression analysis and generalised structural equation modelling (GSEM) were performed.

RESULTS

The prevalence of overweight/obesity was 10.5% and 11.1% in children exposed to GDM and DIP, respectively, and 3.9% in the HFDP-unexposed group. Log-transformed FMI was significantly higher in the DIP-exposed group (β = 0.166, 95% CI = 0.014-0.217 p= .026), but not when adjusting for maternal pregnancy BMI (β = 0.226, 95% CI = 0.003-0.015, p = .004). GSEM showed significant total effects of maternal BMI and birth weight on FMI/BMI.

CONCLUSIONS

Maternal pregnancy BMI seems to play a greater role in the development of childhood adiposity than maternal hyperglycaemia, requiring further research and identifying maternal BMI as a relevant prevention target in our setting.

Adiposity Phenotypes and Subclinical Atherosclerosis in Adults from Sub-Saharan Africa: An H3Africa AWI-Gen Study

Background:

Obesity and adipose tissue distribution contribute to an increased risk of cardiovascular disease (CVD) by promoting atherosclerosis. This association has been poorly studied in sub–Saharan Africa (SSA) despite the rising prevalence of cardiovascular disease.

Objectives:

We determined the association between various adiposity phenotypes and carotid intima–media thickness (CIMT), a proxy of subclinical atherosclerosis, in a large SSA population.

Methods:

A population–based cross–sectional study was performed from 2013–2016 in Burkina Faso, Ghana, Kenya and South Africa. Body mass index (BMI), waist (WC), hip circumferences (HC), visceral (VAT) and subcutaneous adipose tissue (SCAT) using B-mode ultrasound were measured. Ultrasonography of left and right far wall CIMT of the common carotid artery was used as an indicator of subclinical atherosclerosis. Individual participant data meta–analyses were used to determine the associations between adiposity phenotypes and CIMT in the pooled sample while adjusted multivariable linear regression analyses were used for site specific analyses.

Results:

Data were obtained from 9,010 adults (50.3% women and a mean age of 50± 6years). Men had higher levels of visceral fat than women while women had higher BMI, waist and hip circumference and subcutaneous fat than men at all sites except Burkina Faso. In the pooled analyses, BMI (β–value [95% CIs]: 19.5 [16.8, 22.3] μm) showed the strongest relationship with CIMT followed by VAT (5.86 [4.65, 7.07] μm), SCAT (5.00 [2.85, 7.15] μm), WC (1.27 [1.09, 1.44] μm) and HC (1.23 [1.04, 1.42] μm). Stronger associations were observed in men than in women.

Conclusion:

Obesity within SSA will likely result in higher levels of atherosclerosis and promote the occurrence of cardio- and cerebrovascular events, especially in males, unless addressed through primary prevention of obesity in both rural and urban communities across Africa. The inverse association of VAT with CIMT in Burkina Faso and Ghana requires further investigation.

Highlights