Socioeconomic Inequalities in Body Mass Index across Adulthood: Coordinated Analyses of Individual Participant Data from Three British Birth Cohort Studies Initiated in 1946, 1958 and 1970

Exploring the importance of family socio-economic position on the association between parental BMI and offspring BMI trajectories

PURPOSE

We aimed to investigate the associations between parental BMI and offspring BMI trajectories and to explore whether the parent-offspring BMI growth trajectory association differed according to family SEP or social mobility.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC). Children's weight and height were collected from 1 to 18 years. Parents' height and weight were reported pre-pregnancy. We assessed family SEP by measuring parents' and grandparents' educational attainment, social class, and social mobility by changes in education attainment across generations. Multilevel models were used to develop trajectories and assess patterns of change in offspring BMI, to associate parental BMI with these trajectories, and explore whether these associations differed by family SEP and social mobility.

RESULTS

13,612 children were included in the analyses. The average BMI of offspring whose parents were overweight or obese was higher throughout childhood and adolescence, compared to those with parents of normal BMI. Parental and grandparental low SEP were associated with higher child BMI, but there was little evidence of modification of parent-offspring associations. For example, at age 15 years the predicted mean BMI difference between children of overweight or obese mothers versus normal-weight mothers was 12.5 % (95 %CI: 10.1 % to 14.7 %) and 12.2 % (95 %CI: 10.3 % to 13.7 %) for high and low grandparental SEP, respectively.

DISCUSSION

These findings strengthen the evidence that higher parental BMI and lower family SEP were associated with higher offspring BMI, but we did not observe strong evidence that family SEP modifies the parental-offspring BMI association.

When in the lifecourse? Socioeconomic position across the lifecourse and biological health score

PURPOSE

Educational attainment is associated with multiphysiological wear and tear. However, associations with measures of socioeconomic position (SEP) across different life-stages are not established.

METHODS

Using regression models and data from 8105 participants from the UK Household Longitudinal Study (Understanding Society), we examined associations of lifecourse SEP with an overall biological health score (BHS). BHS is broader than usual measures of biological 'wear and tear' and is based on six physiological subsystems (endocrine, metabolic, cardiovascular, inflammatory/immune, liver, and kidney), with higher scores indicating worse health. Lifecourse SEP was based on respondents' parental, first, and most recent occupations.

RESULTS

Associations with SEP at all life-stages demonstrated higher BHS with increasing disadvantage (e.g. slope index of inequality (SII) (95 % CI) for most recent SEP: 0.04 (0.02, 0.06)). There was little difference in the magnitude of associations for SEP measured at each life-stage. Cumulative disadvantage across the lifecourse showed a stepped association with increasing BHS (SII (95 % CI): 0.05 (0.04, 0.07)). Associations were largely driven by metabolic, cardiovascular, and inflammatory systems.

CONCLUSION

Our results suggest that disadvantaged SEP across the lifecourse contributes cumulatively to poorer biological health, highlighting that every life-stage should be a target for public health policies and intervention.

Child-to-adult body size change and risk of type 2 diabetes and cardiovascular disease

AIMS/HYPOTHESIS

Childhood overweight increases the risk of type 2 diabetes and cardiovascular disease in adulthood. However, the impact of childhood leanness on adult obesity and disease risk has been overlooked. We examined the independent and combined influences of child and adult body size on the risk of type 2 diabetes and cardiovascular disease.

METHODS

Data from the UK Biobank on 364,695 individuals of European ancestry and free of type 2 diabetes and cardiovascular disease were divided into nine categories based on their self-reported body size at age 10 and measured BMI in adulthood. After a median follow-up of 12.8 years, 33,460 individuals had developed type 2 diabetes and/or cardiovascular disease. We used Cox regression models to assess the associations of body size categories with disease incidence.

RESULTS

Individuals with low body size in childhood and high body size in adulthood had the highest risk of type 2 diabetes (HR 4.73; 95% CI 4.50, 4.99), compared to those with average body size in both childhood and adulthood. This was significantly higher than the risk in those with high body size in both childhood and adulthood (HR 4.05; 95% CI 3.84, 4.26). By contrast, cardiovascular disease risk was determined by adult body size, irrespective of childhood body size.

CONCLUSIONS/INTERPRETATION

Low body size in childhood exacerbates the risk of type 2 diabetes associated with adult obesity but not the risk of cardiovascular disease. Thus, promoting healthy weight management from childhood to adulthood, among lean children, is crucial.

Living with obesity in Ireland: determinants, policy and future perspectives

Globally, the prevalence of those living with obesity (≥30 kg/m2) is rising, with this trend expected to continue if firm and decisive policy interventions are not introduced. Across Europe, despite many consecutive policies aiming to reverse rising trends in weight status over recent decades, no country is currently on track to halt and reverse current trends in the coming years. This is evident in Ireland too, whereby the reporting of nationally representative weight status data show that targets have not been achieved since reporting began. The aim of this review is to critically appraise recent evidence relating to the key determinants of obesity including weight status, diet quality and physical activity with an emphasis on socioeconomic inequalities. And to consider these in the context of respective policy measures and propose future-focused recommendations. Furthermore, as with the complex nature of obesity, multifaceted approaches that shift the focus from the individual and place responsibility at a societal level will be reviewed.

Social inequalities in pregnancy metabolic profile: findings from the multi-ethnic Born in Bradford cohort study

BACKGROUND

Lower socioeconomic position (SEP) associates with adverse pregnancy and perinatal outcomes and with less favourable metabolic profile in nonpregnant adults. Socioeconomic differences in pregnancy metabolic profile are unknown. We investigated association between a composite measure of SEP and pregnancy metabolic profile in White European (WE) and South Asian (SA) women.

METHODS

We included 3,905 WE and 4,404 SA pregnant women from a population-based UK cohort. Latent class analysis was applied to nineteen individual, household, and area-based SEP indicators (collected by questionnaires or linkage to residential address) to derive a composite SEP latent variable. Targeted nuclear magnetic resonance spectroscopy was used to determine 148 metabolic traits from mid-pregnancy serum samples. Associations between SEP and metabolic traits were examined using linear regressions adjusted for gestational age and weighted by latent class probabilities.

RESULTS

Five SEP sub-groups were identified and labelled 'Highest SEP' (48% WE and 52% SA), 'High-Medium SEP' (77% and 23%), 'Medium SEP' (56% and 44%) 'Low-Medium SEP' (21% and 79%), and 'Lowest SEP' (52% and 48%). Lower SEP was associated with more adverse levels of 113 metabolic traits, including lower high-density lipoprotein (HDL) and higher triglycerides and very low-density lipoprotein (VLDL) traits. For example, mean standardized difference (95%CI) in concentration of small VLDL particles (vs. Highest SEP) was 0.12 standard deviation (SD) units (0.05 to 0.20) for 'Medium SEP' and 0.25SD (0.18 to 0.32) for 'Lowest SEP'. There was statistical evidence of ethnic differences in associations of SEP with 31 traits, primarily characterised by stronger associations in WE women e.g., mean difference in HDL cholesterol in WE and SA women respectively (vs. Highest-SEP) was -0.30SD (-0.41 to -0.20) and -0.16SD (-0.27 to -0.05) for 'Medium SEP', and -0.62SD (-0.72 to -0.52) and -0.29SD (-0.40 to -0.20) for 'Lowest SEP'.

CONCLUSIONS

We found widespread socioeconomic differences in metabolic traits in pregnant WE and SA women residing in the UK. Further research is needed to understand whether the socioeconomic differences we observe here reflect pre-conception differences or differences in the metabolic pregnancy response. If replicated, it would be important to explore if these differences contribute to socioeconomic differences in pregnancy outcomes.

Association between weight loss and health care resource utilization in adults living with obesity: Evidence from a UK primary care database

AIMS

We investigated the impact of intentional weight loss on health care resource utilization (HCRU) and costs among people with obesity.

MATERIALS AND METHODS

This retrospective, observational cohort study used data from the Clinical Practice Research Datalink (CPRD) GOLD database. Adults >18 years at index date [first recorded body mass index (BMI) of 30-50 kg/m2 between 2006 and 2015 with a further BMI record 4 years later] were assigned to an intentional weight loss cohort (-25% to -10% BMI change) or a stable weight cohort (-3% to +3%), based on their BMI change during a 4-year baseline period from index date. Evidence of intention to lose weight during the baseline period was required. Linked Hospital Episode Statistics datasets captured HCRU and costs over an 8-year follow-up period. Mixed effects models adjusted for demographics, total costs during baseline and baseline comorbidities were used.

RESULTS

Baseline characteristics were similar between cohorts with weight loss (n = 8676) and stable weight (n = 44 519). Over follow-up, the weight loss cohort experienced a significantly lower mean annual increase in total costs [2.1% (95% confidence interval: 1.3-2.8)] than the stable weight cohort [4.3% (95% confidence interval: 4.0-4.6); p < .0001]. Weight loss was associated with a lower mean annual increase in multiple HCRU and cost components compared with maintaining a stable high weight.

CONCLUSIONS

Our findings suggest that intentional weight loss of 10-25% is associated with lower HCRU and costs in the long term among individuals living with obesity, relative to stable weight.

Trends in the ability of socioeconomic position to predict individual body mass index: an analysis of repeated cross-sectional data, 1991-2019

BACKGROUND

The widening of group-level socioeconomic differences in body mass index (BMI) has received considerable research attention. However, the predictive power of socioeconomic position (SEP) indicators at the individual level remains uncertain, as does the potential temporal variation in their predictive value. Examining this is important given the increasing incorporation of SEP indicators into predictive algorithms and calls to reduce social inequality to tackle the obesity epidemic. We thus investigated SEP differences in BMI over three decades of the obesity epidemic in England, comparing population-wide (SEP group differences in mean BMI) and individual-level (out-of-sample prediction of individuals' BMI) approaches to understanding social inequalities.

METHODS

We used repeated cross-sectional data from the Health Survey for England, 1991-2019. BMI (kg/m2) was measured objectively, and SEP was measured via educational attainment, occupational class, and neighbourhood index of deprivation. We ran random forest models for each survey year and measure of SEP adjusting for age and sex.

RESULTS

The mean and variance of BMI increased within each SEP group over the study period. Mean differences in BMI by SEP group also increased: differences between lowest and highest education groups were 1.0 kg/m2 (0.4, 1.6) in 1991 and 1.3 kg/m2 (0.7, 1.8) in 2019. At the individual level, the predictive capacity of SEP was low, though increased in later years: including education in models improved predictive accuracy (mean absolute error) by 0.14% (- 0.9, 1.08) in 1991 and 1.05% (0.18, 1.82) in 2019. Similar patterns were obtained for occupational class and neighbourhood deprivation and when analysing obesity as an outcome.

CONCLUSIONS

SEP has become increasingly important at the population (group difference) and individual (prediction) levels. However, predictive ability remains low, suggesting limited utility of including SEP in prediction algorithms. Assuming links are causal, abolishing SEP differences in BMI could have a large effect on population health but would neither reverse the obesity epidemic nor reduce much of the variation in BMI.

Dementia incidence trend in England and Wales, 2002-19, and projection for dementia burden to 2040: analysis of data from the English Longitudinal Study of Ageing

BACKGROUND

Dementia incidence declined in many high-income countries in the 2000s, but evidence on the post-2010 trend is scarce. We aimed to analyse the temporal trend in England and Wales between 2002 and 2019, considering bias and non-linearity.

METHODS

Population-based panel data representing adults aged 50 years and older from the English Longitudinal Study of Ageing were linked to the mortality register across wave 1 (2002-03) to wave 9 (2018-19) (90 073 person observations). Standard criteria based on cognitive and functional impairment were used to ascertain incident dementia. Crude incidence rates were determined in seven overlapping initially dementia-free subcohorts each followed up for 4 years (ie, 2002-06, 2004-08, 2006-10, 2008-12, 2010-14, 2012-16, and 2014-18). We examined the temporal trend of dementia incidence according to age, sex, and educational attainment. We estimated the trend of dementia incidence adjusted by age and sex with Cox proportional hazards and multistate models. Restricted cubic splines allowed for potential non-linearity in the time trend. A Markov model was used to project future dementia burden considering the estimated incidence trend.

FINDINGS

Incidence rate standardised by age and sex declined from 2002 to 2010 (from 10·7 to 8·6 per 1000 person-years), then increased from 2010 to 2019 (from 8·6 to 11·3 per 1000 person-years). Adjusting for age and sex, and accounting for missing dementia cases due to death, estimated dementia incidence declined by 28·8% from 2002 to 2008 (incidence rate ratio 0·71, 95% CI 0·58-0·88), and increased by 25·2% from 2008 to 2016 (1·25, 1·03-1·54). The group with lower educational attainment had a smaller decline in dementia incidence from 2002 to 2008 and a greater increase after 2008. If the upward incidence trend continued, there would be 1·7 million (1·62-1·75) dementia cases in England and Wales by 2040, 70% more than previously forecast.

INTERPRETATION

Dementia incidence might no longer be declining in England and Wales. If the upward trend since 2008 continues, along with population ageing, the burden on health and social care will be large.

FUNDING

UK Economic and Social Research Council.

Socio-economic accounting of inequalities in excess weight: a population-based analysis

BACKGROUND

The prevalence of excess weight has been increasing globally in the last decades, affecting disproportionally adults from low socio-economic backgrounds and putting undue pressure on health systems and societal resources. In England, tackling unfair and unjust health inequalities is at the heart of national public health policy, and a prerequisite for enabling these decision makers to set policy priorities is an understanding of the prevalence and determinants of excess weight inequalities in their local population.

METHODS

We conducted both pooled (England) and regional-level (nine regions: North-East, North-West, Yorkshire and Humber, East Midlands, West Midlands, East of England, London, South East and South West) analyses of individual level data from a nationally representative sample of adults (N = 6,387). We used the Corrected Concentration Index (CCI) to measure absolute inequalities in excess weight across three dimensions of socio-economic deprivation: neighbourhood-level deprivation, occupational status and educational qualification. We used a Shapley decomposition method to evaluate their relative contribution to inequality.

RESULTS

At a national level, all three dimensions of socio-economic deprivation were found to be positively associated with excess weight across the adult population, as measured by the CCI, with educational qualification ranking first [CCI: -0.090, p < 0.01], closely followed by neighbourhood-level deprivation [CCI: -0.050, p < 0.01]. Large variation was found between regions and genders, with inequality being either considerably higher or exclusively patterned among women. The strongest independent factor contributing to excess weight inequalities was having a long-lasting limiting illness, especially among women and towards the right tail of the excess weight spectrum. Heterogeneous patterns of contribution across the excess weight spectrum were found, however age played a dominant role toward the left tail of the distribution.

CONCLUSIONS

While socio-economic inequalities in excess weight exist in the English adult population, our findings underscore the importance of considering multiple dimensions of deprivation and the unique needs of different populations when developing policies to address overweight and obesity. Targeted interventions for adults with overweight and obesity with long-lasting illnesses and women can generate both short-term and long-term economic benefits, by reducing healthcare costs and increasing workforce productivity.

The association between cognitive ability and body mass index: A sibling-comparison analysis in four longitudinal studies

BACKGROUND

Body mass index (BMI) and obesity rates have increased sharply since the 1980s. While multiple epidemiologic studies have found that higher adolescent cognitive ability is associated with lower adult BMI, residual and unobserved confounding due to family background may explain these associations. We used a sibling design to test this association accounting for confounding factors shared within households.

METHODS AND FINDINGS

We used data from four United States general youth population cohort studies: the National Longitudinal Study of Youth 1979 (NLSY-79), the NLSY-79 Children and Young Adult, the NLSY 1997 (NLSY-97), and the Wisconsin Longitudinal Study (WLS); a total of 12,250 siblings from 5,602 households followed from adolescence up to age 62. We used random effects within-between (REWB) and residualized quantile regression (RQR) models to compare between- and within-family estimates of the association between adolescent cognitive ability and adult BMI (20 to 64 years). In REWB models, moving from the 25th to 75th percentile of adolescent cognitive ability was associated with -0.95 kg/m2 (95% CI = -1.21, -0.69) lower BMI between families. Adjusting for family socioeconomic position reduced the association to -0.61 kg/m2 (-0.90, -0.33). However, within families, the association was just -0.06 kg/m2 (-0.35, 0.23). This pattern of results was found across multiple specifications, including analyses conducted in separate cohorts, models examining age-differences in association, and in RQR models examining the association across the distribution of BMI. Limitations include the possibility that within-family estimates are biased due to measurement error of the exposure, confounding via non-shared factors, and carryover effects.

CONCLUSIONS

The association between high adolescent cognitive ability and low adult BMI was substantially smaller in within-family compared with between-family analysis. The well-replicated associations between cognitive ability and subsequent BMI may largely reflect confounding by family background factors.

Effectiveness of eHealth weight management interventions in overweight and obese adults from low socioeconomic groups: a systematic review

Background

Low socioeconomic status (SES) is associated with increased rates of overweight and obesity. Proponents of electronic health (eHealth) hypothesise that its inclusion in weight management interventions can improve efficacy by mitigating typical barriers associated with low SES.

Objectives

To establish the scope of eHealth weight management interventions for people with overweight and obesity from a low SES. Secondary objectives were to determine the efficacy of eHealth interventions in facilitating weight loss, physical activity and fitness improvements.

Methods

Four databases and grey literature were systematically searched to identify eligible studies published in English from inception to May 2021. Studies examining an eHealth intervention with low SES participants were included. Outcomes included temporal change in weight and BMI, anthropometry, physiological measures and physical activity levels. The number and heterogeneity of studies precluded any meta-analyses; thus, a narrative review was undertaken.

Results

Four experimental studies with low risk of bias were reviewed. There was variance in how SES was defined. Study aims and eHealth media also varied and included reducing/maintaining weight or increasing physical activity using interactive websites or voice responses, periodic communication and discourse via telephone, social media, text messaging or eNewsletters. Irrespectively, all studies reported short-term weight loss. eHealth interventions also increased short-term physical activity levels where it was assessed, but did not change anthropometry or physiological measures. None reported any effect on physical fitness.

Conclusions

This review revealed short-term effects of eHealth interventions on weight loss and increased physical activity levels for low SES participants. Evidence was limited to a small number of studies, with small to moderate sample sizes. Inter-study comparison is challenging because of considerable variability. Future work should prioritise how to utilise eHealth in the longer term either as a supportive public health measure or by determining its long-term efficacy in engendering volitional health behaviour changes.

Systematic review registration

PROSPERO CRD42021243973

Supplementary Information

The online version contains supplementary material available at 10.1186/s13643-023-02207-3.

Mechanisms of Maternal Diet-Induced Obesity Affecting the Offspring Brain and Development of Affective Disorders

Depression and metabolic disease are common disorders that share a bidirectional relationship and continue to increase in prevalence. Maternal diet and maternal behaviour both profoundly influence the developmental trajectory of offspring during the perinatal period. At an epidemiological level, both maternal depression and obesity during pregnancy have been shown to increase the risk of neuropsychiatric disease in the subsequent generation. Considerable progress has been made to understand the mechanisms by which maternal obesity disrupts the developing offspring gut-brain axis, priming offspring for the development of affective disorders. This review outlines such mechanisms in detail, including altered maternal care, the maternal microbiome, inflammation, breast milk composition, and maternal and placental metabolites. Subsequently, offspring may be prone to developing gut-brain interaction disorders with concomitant changes to brain energy metabolism, neurotransmission, and behaviour, alongside gut dysbiosis. The gut microbiome may act as a key modifiable, and therefore treatable, feature of the relationship between maternal obesity and the offspring brain function. Further studies examining the relationship between maternal nutrition, the maternal microbiome and metabolites, and offspring neurodevelopment are warranted to identify novel therapeutic targets.

Modelling the impact of diet and physical activity on body mass index in pre-pregnant and postpartum women

OBJECTIVES

This study aimed to assess, using simulation modeling, the theoretical effect of key diet and physical activity (PA) modification scenarios could have on body mass index (BMI) in prepregnant and postpartum women.

METHODS

Simulation modeling using data from the 2011 to 2012 National Nutrition and Physical Activity Survey was performed for a subsample of prepregnant and postpartum women. The regression coefficients for each diet and PA component from multivariable linear regression equations for BMI were used to calculate a predicted BMI. Scenario modeling using a moderation approach was applied to targeted diet and PA components for the entire sample and subgroups of populations of women who failed to meet dietary and PA recommendations and among the lowest socioeconomic groups.

RESULTS

In prepregnancy and postpartum scenarios, respectively, increasing whole grains by 2 to 3 servings/d reduced BMI by 1.16 and 0.85 kg/m². For postpartum women, BMI was reduced by 0.28 kg/m² for every 5-g/d increase in fiber intake. A 480- and 540-min/wk increase in PA resulted in average BMI reductions of 0.95 and 1.19 kg/m² in prepregnant and postpartum women, respectively. A similar pattern of theoretical reductions in BMI was observed with increased whole grains, fiber, and PA among the most disadvantaged socioeconomic groups of women.

CONCLUSIONS

Increasing intake of whole grains by 2 to 3 servings/d could result in reductions in BMI of 1.16 and 0.85 kg/m², and a 480- and 540-min/wk increase in PA could result in BMI reduction of 0.95 and 1.19 kg/m² in prepregnant and postpartum women, respectively. This provides an evidence base to guide tailored nutrition messaging for obesity prevention efforts in reproductive age women.

Women carry the weight of deprivation on physical inactivity: Moderated mediation analyses in a European sample of adults over 50 Years of age

Deprived people are less physically active than privileged individuals. However, pathways underlying the association between deprivation and physical activity remain overlooked. We examined whether the association between deprivation and physical activity was mediated by body mass index (BMI). Consistent with an intersectional perspective (how the combination of belongingness to vulnerable social categories widens inequalities), we tested whether gender moderated this mediating pathway and hypothesized that the mediating effect of BMI would be stronger among women (vs men). Large-scale longitudinal data from 20,961 adults 50 years of age or older (57% women) from the Survey of Health, Ageing and Retirement in Europe were used. Social and material deprivation were measured by questionnaire, BMI and physical activity were reported from two to six years later. Simple mediation models showed that BMI partly mediated the association of material (total effect c = -0.14, proportion of mediated effect = 8%) and of social deprivation (c = -0.24, proportion of mediated effect = 4%) with physical activity. Moderated mediation models revealed that this mediating pathway was moderated by gender. The effect of deprivation on BMI was stronger among women (vs men), with BMI mediating 18% and 7% of the association of material and social deprivation with physical activity among women (vs 4% and 2% among men). Lower levels of physical activity observed among deprived older adults could be partly attributed to a higher BMI. Critically, this mechanism was exacerbated among women, reinforcing the need to understand how deprivation and gender interact to predict health behaviors.

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Body mass index mediates the association of material and social deprivation with physical activity.

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This mediating pattern is more pronounced among women, relative to men.

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The association between deprivation and a higher body mass index is exacerbated among women, compared to men.

Investigating change across time in prevalence or association: the challenges of cross-study comparative research and possible solutions

Cross-study research initiatives to understand change across time are an increasingly prominent component of social and health sciences, yet they present considerable practical, analytical and conceptual challenges. First, we discuss the key challenges to comparative research as a basis for detecting societal change, as well as possible solutions. We focus on studies which investigate changes across time in outcome occurrence or the magnitude and/or direction of associations. We discuss the use and importance of such research, study inclusion, sources of bias and mitigation, and interpretation. Second, we propose a structured framework (a checklist) that is intended to provide guidance for future authors and reviewers. Third, we outline a new open-access teaching resource that offers detailed instruction and reusable analytical syntax to guide newcomers on techniques for conducting comparative analysis and data visualisation (in both R and Stata formats).

Supplementary Information

The online version contains supplementary material available at 10.1007/s44155-022-00021-1.

A prospective cohort study of the association between key family and individual factors and obesity status among youth

There remains a significant gap in our knowledge of the synergistic nature of family dynamics, child characteristics, and child-rearing features in the etiology of obesity from childhood through adolescence. We assessed the associations of family dynamics (poverty, family structure), child characteristics (child temperament), and child-rearing features (maternal depression, maternal sensitivity, and type of child care) with the development of childhood obesity. Children (n = 1240) whose weights and heights were measured at least once for ten time points (from 2 years through 15 years) from the NICHD Study of Early Child Care and Youth Development were included. Generalized estimating equation (GEE) was used to examine the associations of family and individual factors with the childhood obesity after adjusting for covariates. Adjusted GEE models showed that living below poverty level was associated with an increased odds of obesity (odds ratio = 1.62, 95% confidence interval 1.05, 2.53). Among these key family and individual factors, poverty status was observed to be the strongest predictor of obesity of offspring across time. Findings highlight the importance of systemic-level public health changes in obesity reduction efforts and suggest that poverty-reduction based prevention and intervention are likely more effective targets than more individual/family specific targets.

Disparities in the Prevalence of Childhood Obesity-Related Comorbidities: A Systematic Review

Background

Non-communicable diseases among children are serious consequences of childhood obesity. However, less is known about the disparities in childhood obesity comorbidities burden. This review describes the salient pattern of disparities in the prevalence of childhood obesity-related non-communicable diseases and relevant inequalities in both high- and low/medium-income countries.

Method

A systematic literature search was performed in MEDLINE, Embase, CINAHL, PsycInfo, Scopus, and Web of Science databases by two independent reviewers. Inclusion criteria were as follows: age 2–18 years; the prevalence or incidence of childhood obesity comorbidities reported; and studies published in English from January 2010 to date. No restrictions on the setting. The prevalence data were analyzed using range and median for subgroups based on the country's development status, gender, and geographical region.

Results

Our search identified 6,837 articles, out of which we examined 145 full-text articles and included 54 articles in the analysis. The median prevalence of childhood obesity-related hypertension was 35.6 vs. 12.7% among middle- and low-income countries compared with high-income countries; 37.7 vs. 32.9% among boys compared with girls; and 38.6, 25.3, and 20.1% in Asia, South America, and Europe, respectively. For metabolic syndrome, the median prevalence was 26.9 vs. 5.5% among middle- and low-income countries compared with high-income countries; 55.2 vs. 12.0% among boys compared with girls; and 40.3, 25.8, and 7.7% in South America, Asia, and Europe, respectively. The prevalence of childhood obesity-related non-alcoholic fatty liver disease was 47.5 vs. 23% among middle- and low-income countries compared with high-income countries; and 52.1, 39.7, and 23.0% in Asia, South America, and Europe, respectively. The median prevalence of dyslipidemia was 43.5 vs. 63% among middle- and low-income countries compared with high-income countries; 55.2 vs. 12.0% among boys compared to girls; and 73.7 and 49.2% in Australia and Europe, respectively.

Conclusion

There are disparities in the prevalence of childhood obesity-related hypertension, metabolic syndrome, and non-alcoholic fatty liver disease, with middle- and low-income countries, boys, and Asian region having higher prevalence. Implementing targeted interventions for childhood obesity comorbidities should consider socioeconomic disparities and strengthening of research surveillance methods for a better understanding of non-communicable disease burden in the pediatric population.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42021288607.

Polygenic and socioeconomic risk for high body mass index: 69 years of follow-up across life

Genetic influences on body mass index (BMI) appear to markedly differ across life, yet existing research is equivocal and limited by a paucity of life course data. We thus used a birth cohort study to investigate differences in association and explained variance in polygenic risk for high BMI across infancy to old age (2-69 years). A secondary aim was to investigate how the association between BMI and a key purported environmental determinant (childhood socioeconomic position) differed across life, and whether this operated independently and/or multiplicatively of genetic influences. Data were from up to 2677 participants in the MRC National Survey of Health and Development, with measured BMI at 12 timepoints from 2-69 years. We used multiple polygenic indices from GWAS of adult and childhood BMI, and investigated their associations with BMI at each age. For polygenic liability to higher adult BMI, the trajectories of effect size (β) and explained variance (R2) diverged: explained variance peaked in early adulthood and plateaued thereafter, while absolute effect sizes increased throughout adulthood. For polygenic liability to higher childhood BMI, explained variance was largest in adolescence and early adulthood; effect sizes were marginally smaller in absolute terms from adolescence to adulthood. All polygenic indices were related to higher variation in BMI; quantile regression analyses showed that effect sizes were sizably larger at the upper end of the BMI distribution. Socioeconomic and polygenic risk for higher BMI across life appear to operate additively; we found little evidence of interaction. Our findings highlight the likely independent influences of polygenic and socioeconomic factors on BMI across life. Despite sizable associations, the BMI variance explained by each plateaued or declined across adulthood while BMI variance itself increased. This is suggestive of the increasing importance of chance ('non-shared') environmental influences on BMI across life.

DNA Methylation Mediates the Association Between Individual and Neighborhood Social Disadvantage and Cardiovascular Risk Factors

Low socioeconomic status (SES) and living in a disadvantaged neighborhood are associated with poor cardiovascular health. Multiple lines of evidence have linked DNA methylation to both cardiovascular risk factors and social disadvantage indicators. However, limited research has investigated the role of DNA methylation in mediating the associations of individual- and neighborhood-level disadvantage with multiple cardiovascular risk factors in large, multi-ethnic, population-based cohorts. We examined whether disadvantage at the individual level (childhood and adult SES) and neighborhood level (summary neighborhood SES as assessed by Census data and social environment as assessed by perceptions of aesthetic quality, safety, and social cohesion) were associated with 11 cardiovascular risk factors including measures of obesity, diabetes, lipids, and hypertension in 1,154 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). For significant associations, we conducted epigenome-wide mediation analysis to identify methylation sites mediating the relationship between individual/neighborhood disadvantage and cardiovascular risk factors using the JT-Comp method that assesses sparse mediation effects under a composite null hypothesis. In models adjusting for age, sex, race/ethnicity, smoking, medication use, and genetic principal components of ancestry, epigenetic mediation was detected for the associations of adult SES with body mass index (BMI), insulin, and high-density lipoprotein cholesterol (HDL-C), as well as for the association between neighborhood socioeconomic disadvantage and HDL-C at FDR q < 0.05. The 410 CpG mediators identified for the SES-BMI association were enriched for CpGs associated with gene expression (expression quantitative trait methylation loci, or eQTMs), and corresponding genes were enriched in antigen processing and presentation pathways. For cardiovascular risk factors other than BMI, most of the epigenetic mediators lost significance after controlling for BMI. However, 43 methylation sites showed evidence of mediating the neighborhood socioeconomic disadvantage and HDL-C association after BMI adjustment. The identified mediators were enriched for eQTMs, and corresponding genes were enriched in inflammatory and apoptotic pathways. Our findings support the hypothesis that DNA methylation acts as a mediator between individual- and neighborhood-level disadvantage and cardiovascular risk factors, and shed light on the potential underlying epigenetic pathways. Future studies are needed to fully elucidate the biological mechanisms that link social disadvantage to poor cardiovascular health.

Education, income, and obesity: A nationwide Chinese twin study

OBJECTIVE

This study aimed to examine the association of socioeconomic status with obesity.

METHODS

A total of 39,262 twin individuals were included from the Chinese National Twin Registry (CNTR). Generalized estimating equation models for unmatched twin individual analyses and conditional logistic regression for the co-twin matched design were used. Inference about Causation through Examination of FAmiliaL CONfounding (ICE FALCON) was used to explore the evidence of a causal relationship.

RESULTS

In general estimating equation models, high education level and income were associated with lower risk of obesity (odds ratio [OR] = 0.74 [95% CI: 0.65 to 0.84] and 0.86 [95% CI: 0.77 to 0.96]). In conditional logistic regression analysis, the association with education was significant (OR = 0.50 [95% CI: 0.34 to 0.74]) but the association with income was insignificant (OR = 0.74 [95% CI: 0.48 to 1.15]). From the ICE FALCON analysis, a twin's obesity was associated with the co-twin's education and income. After adjusting for the twin's own education, the association disappeared ( β co - twin '  = -0.10 [95% CI: -0.26 to 0.07]), whereas the twin's obesity was still associated with the co-twin's income but attenuated toward the null ( β co - twin '  = -0.21 [95% CI: -0.36 to -0.06]).

CONCLUSIONS

Socioeconomic status is negatively associated with obesity. Education may have a causal effect on obesity, whereas the association between income and obesity is confounded by familial factors.

Outcomes Following eHealth Weight Management Interventions in Adults With Overweight and Obesity From Low Socioeconomic Groups: Protocol for a Systematic Review

BACKGROUND

Obesity is a complex health condition with multiple associated comorbidities and increased economic costs. People from low socioeconomic status (SES) backgrounds are more likely to be overweight and obese and are less successful in traditional weight management programs. It is possible that eHealth interventions may be more successful in reaching people from low SES groups than traditional face-to-face models, by overcoming certain barriers associated with traditional interventions. It is not yet known, however, if eHealth weight management interventions are effective in people living with overweight and obesity from a low SES background.

OBJECTIVE

The primary aim of this study is to evaluate the efficacy of eHealth weight management interventions for people with overweight and obesity from low SES groups.

METHODS

A systematic review on relevant electronic databases (MEDLINE, Embase, Emcare, and CINAHL) will be undertaken to identify eligible studies published in English up until May 2021. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement to guide the systematic review, two reviewers will independently screen, select, and extract data and complete a risk of bias assessment of search results according to predefined criteria. Studies that have investigated an eHealth weight management intervention within a low SES population will be included. Primary outcomes include weight, BMI, and percentage weight change compared at baseline and at least one other time point. Secondary outcomes may include a range of anthropometric and physical fitness and activity measures. If sufficient studies are homogeneous, then we will pool results of individual outcomes using meta-analysis.

RESULTS

Searches have been completed, resulting in 2256 studies identified. Once duplicates were removed, 1545 studies remained for title and abstract review.

CONCLUSIONS

The use of eHealth in weight management programs has increased significantly in recent years and will continue to do so; however, it is uncertain if eHealth weight management programs are effective in a low SES population. The results of this systematic review will therefore provide a summary of the evidence for interventions using eHealth for people living with overweight and obesity and from a low SES background.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews CRD42021243973; https://tinyurl.com/2p8fxtnw.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/34546.

Long-Term Trends in Obesity Prevalence by Socio-Economic Group in Five European Countries and the USA: The Relevance of the Diffusion of Innovations Theory

INTRODUCTION

Cross-national comparison suggests that the timing of the obesity epidemic differs across socio-economic groups (SEGs). Similar to the smoking epidemic, these differences might be described by the diffusion of innovations theory, which states that health behaviours diffuse from higher to lower SEGs. However, the applicability of the diffusion of innovations theory to long-term time trends in obesity by SEG is unknown. We studied long-term trends in the obesity prevalence by SEG in England, France, Finland, Italy, Norway, and the USA and examined whether trends are described by the diffusion of innovations theory.

METHODS

Obesity prevalence from 1978 to 2019 by educational level, sex, and age group (25+ years) from health surveys was harmonized, age-standardized, Loess-smoothed, and visualized. Prevalence rate differences were calculated, and segmented regression was performed to obtain annual percentage changes, which were compared over time and across SEGs.

RESULTS

Obesity prevalence among lower educated groups has exceeded that of higher educated groups, except among American men, in all countries throughout the study period. A comparable increase across educational levels was observed until approximately 2000. Recently, obesity prevalence stagnated among higher educated groups in Finland, France, Italy, and Norway and lower educated groups in England and the USA.

DISCUSSION

Recent trends in obesity prevalence by SEG are mostly in line with the diffusion of innovations theory; however, no diffusion from higher to lower SEGs at the start of the epidemic was found. The stagnation among higher SEGs but not lower SEGs suggests that the latter will likely experience the greatest future burden.

Overweight and Obesity Are Associated With Acute Kidney Injury and Acute Respiratory Distress Syndrome, but Not With Increased Mortality in Hospitalized COVID-19 Patients: A Retrospective Cohort Study

Objective

To evaluate the association between overweight and obesity on the clinical course and outcomes in patients hospitalized with COVID-19.

Design

Retrospective, observational cohort study.

Methods

We performed a multicenter, retrospective, observational cohort study of hospitalized COVID-19 patients to evaluate the associations between overweight and obesity on the clinical course and outcomes.

Results

Out of 1634 hospitalized COVID-19 patients, 473 (28.9%) had normal weight, 669 (40.9%) were overweight, and 492 (30.1%) were obese. Patients who were overweight or had obesity were younger, and there were more women in the obese group. Normal-weight patients more often had pre-existing conditions such as malignancy, or were organ recipients. During admission, patients who were overweight or had obesity had an increased probability of acute respiratory distress syndrome [OR 1.70 (1.26-2.30) and 1.40 (1.01-1.96)], respectively and acute kidney failure [OR 2.29 (1.28-3.76) and 1.92 (1.06-3.48)], respectively. Length of hospital stay was similar between groups. The overall in-hospital mortality rate was 27.7%, and multivariate logistic regression analyses showed that overweight and obesity were not associated with increased mortality compared to normal-weight patients.

Conclusion

In this study, overweight and obesity were associated with acute respiratory distress syndrome and acute kidney injury, but not with in-hospital mortality nor length of hospital stay.

BMI and related risk factors among U.S. Marshallese with diabetes and their families

Objective: Examine cross-sectional associations between body mass index (BMI) and related health behaviors, barriers and facilitators to health care, and perceived health status among a sample of U.S. Marshallese adults with Type 2 diabetes and evaluate associations of interest between participants and their family members.Design: Cross-sectional baseline data were analyzed from participants in a diabetes self-management education intervention trial.Setting: Data collection took place in home or community settings through a community-academic partnership in Arkansas.Participants: Study participants consisted of U.S. Marshallese adults with Type 2 diabetes (N = 221) and their family members (N = 211) recruited through community settings.Intervention(s): N/A.Main Outcome Measure(s): Participants' height and weight were measured using standard protocols to calculate BMI (kg/m2). Diet, physical activity, health care access, financial strain related to health care, perceived health status, and health care satisfaction were measured using self-report surveys.Results: Participants' mean BMI was 31.0 (95% CI: 30.2-31.7), with over half of study participants and their family members' BMI falling in the obese category. Participants' BMI was positively associated with spreading health care bill payments over time (β = 1.75 (SE = 0.87); p = 0.045). Positive associations between participants and their family members were observed for self-reported health status conditions, health care coverage, health care utilization, and health care satisfaction.Conclusion: Study findings highlight the high prevalence of obesity and related risk factors among U.S. Marshallese adults with Type 2 diabetes and emphasize the need for intervention strategies that build upon cultural strengths and target community, policy, systems, and environmental changes to address obesity and chronic disease in this marginalized community.

Socioeconomic position and body composition in childhood in high- and middle-income countries: a systematic review and narrative synthesis

BACKGROUND

The relation between socioeconomic position (SEP) and obesity measured by body mass index (BMI), a measure of weight for height, has been extensively reviewed in children, showing consistent associations between disadvantaged SEP and higher BMI in high-income countries (HICs) and lower BMI in middle-income countries (MICs). Fat mass (FM), a more accurate measure of adiposity, and fat-free mass (FFM) are not captured by BMI, but have been shown to track from childhood to adulthood, and be important for cardiovascular health and functional outcomes in later life. It is not clear whether body composition is associated with SEP. We systematically reviewed the association between SEP and body composition in childhood.

METHODS

A systematic review was carried out following PRISMA guidelines. The protocol was pre-registered with PROSPERO (CRD42019119937). Original studies in the English language, which examined the association between SEP and body composition in childhood, were included. An electronic search of three databases was conducted. Two independent reviewers carried out screening, data extraction and quality assessment. Due to heterogeneity in results, a narrative synthesis was conducted. Heterogeneity in findings according to SEP, sex, body composition measure and country income level was investigated.

RESULTS

50 papers were included, the majority from HICs. No papers were from low-income countries. Disadvantage in childhood was associated with greater FM and lower FFM in HICs, but with lower FM and lower FFM in MICs. When measures of FFM indexed to height were used there was no evidence of associations with SEP. In HICs, more studies reported associations between disadvantaged SEP and higher FM among girls comparative to boys.

CONCLUSIONS

Inequalities in FM are evident in HICs and, in the opposite direction, in MICs and follow similar trends to inequalities for BMI. Inequalities in height are likely important in understanding inequalities in FFM.

Social mobility by parent education and childhood overweight and obesity: a prospective cohort study

BACKGROUND

The association of social mobility, measured by parent education and childhood overweight and obesity (OWOB) has been scarcely reported on. This study evaluated the associations between social mobility measured by parent education and childhood OWOB at child age 6 and 10 years.

METHODS

We analyzed data of 4030 children and parents participating in the Generation R study. We used generalized linear models controlling for potential confounders to determine if social mobility (upward mobility, static-low and static-high based on the change of parent education) was associated with age- and sex-specific standard deviation scores of body mass index (BMI-SDS) or OWOB (the cut-offs of International Obesity Task Force).

RESULTS

Mean BMI-SDS of the children was 0.23 ± 0.89 and 0.26 ± 1.03 at child age 6 and 10 years, respectively; the prevalence of OWOB increased from 15.2 to 17.4%. Compared with children from mothers in the upward mobility group, children from mothers in the static-high group had lower BMI-SDS and lower odds of OWOB at both ages (all P < 0.001). Compared with children from fathers in the upward mobility group, children from fathers in static-low group had higher BMI-SDS and higher odds of OWOB at both ages (all P < 0.05).

CONCLUSIONS

Our study contributes to the literature by showing that the behaviors of parents' obtaining a higher level of education after the child was born may be beneficial to attenuate the odds of the child developing overweight in late childhood.

Transient elastography in patients at risk of liver fibrosis in primary care: a follow-up study over 54 months

Background

Liver fibrosis assessment services using transient elastography are growing in primary care. These services identify patients requiring specialist referral for liver fibrosis, and provide an opportunity for recommending lifestyle change. However, there are uncertainties regarding service design, effectiveness of advice given, and frequency of follow-up.

Aim

To assess the following: (a) effectiveness of standard care lifestyle advice for weight management and alcohol consumption; (b) uptake for liver rescan; and (c) usefulness of a 4.5-year time interval of rescanning in monitoring progression of liver fibrosis.

Design & setting

Analysis of patient outcomes 4.5 years after the first ‘liver service’ attendance that included transient elastography in five GP practices in Southampton, UK.

Method

Outcomes included weight, alcohol consumption, rescan uptake, time interval between scans, and change in liver fibrosis stage.

Results

A total of 401 participants were recontacted. Mean standard deviation (± SD) weight loss was 1.2 kg±8.4 kg (P = 0.005); Alcohol Use Disorders Identification Test (AUDIT) grade increased by 7.8% (P ≤0.001). A total of n = 116/401 participants were eligible for liver rescanning and n = 59/116 (50.9%) agreed to undergo rescanning. Mean ± SD time interval between scans was 53.6±3.4 months. Liver fibrosis progressed from mild (≥6.0 kPa–8.1 kPa) to significant fibrosis (8.2 kPa–9.6 kPa) in 3.4% of patients; from mild to advanced fibrosis (9.7 kPa–13.5 kPa) and cirrhosis (≥13.6 kPa) in 15.3% of patients, and did not progress in 81.3%. No baseline factors were independently associated with liver fibrosis progression at follow-up.

Conclusion

Rescan recall attendance and adherence to lifestyle changes needs improving. Optimum time interval between scans remains uncertain. After a mean interval of 53.6 months between scans, and with no specific predictors indicated, a substantial minority (18.7%) experienced a deterioration in fibrosis grade.

National nutrition policy in high-income countries: is health equity on the agenda?

OBJECTIVE

Equity-oriented policy actions are a key public health principle. In this study, how equity and socioeconomic inequalities are represented in policy problematizations of population nutrition were examined.

DATA SOURCES

We retrieved a purposive sample of government nutrition-policy documents (n = 18) from high-income nations.

DATA SYNTHESIS

Thematic analysis of policy documents was informed by a multitheoretical understanding of equitable policies and Bacchi's "What's the Problem Represented to be?' analysis framework. Despite common rhetorical concerns about the existence of health inequalities, these concerns were often overshadowed by greater emphasis on lifestyle "problems" and reductionist policy actions. The notion that policy actions should be for all and reach everyone were seldom backed by specific actions. Rhetorical acknowledgements of the upstream drivers of health inequalities were also rarely problematized, as were government responsibilities for health equity and the role of policy and governance in reducing socioeconomic inequalities in nutrition.

CONCLUSION

To positively influence health equity outcomes, national nutrition policy will need to transition toward the prioritization of actions that uphold social justice and comprehensively address the upstream determinants of health.

Area-level and family-level socioeconomic position and body composition trajectories: longitudinal analysis of the UK Millennium Cohort Study

BACKGROUND

Inequalities in the trajectories of body composition in childhood and adolescence have been infrequently studied. Despite the importance of environmental factors in obesity development, little research has looked at area-level socioeconomic position, independent of family socioeconomic position. We aimed to assess how inequalities in body composition develop with age.

METHODS

The Millennium Cohort Study is a longitudinal study of 19 243 families who had a child born between 2000 and 2002 in the UK. Multilevel growth curve models were applied to examine change in fat mass index (FMI), fat free mass index (FFMI; using the Benn index), and fat mass to fat free mass ratio (FM:FFM), measured using Bioelectrical Impedance Analysis, from ages 7 years to 17 years by the Index of Multiple Deprivation (IMD) and household income at baseline.

FINDINGS

Inequalities in FMI and FM:FFM ratio are evident at age 7 years and widen with age. At age 17 years, adolescents in the most disadvantaged IMD group had FMI 0·57 kg/mB (B=Benn parameter; 95% CI 0·43 to 0·70) higher and FM:FFM ratio 0·037 (95% CI 0·026 to 0·047) higher compared with the most advantaged group. Disadvantaged socioeconomic position is associated with higher FFMI but is reversed in adolescence after adjustment for FMI. Inequalities were greater in girls at age 7 years (mean FMI 0·22 kg/mB; 95% CI 0·13 to 0·32) compared with boys of the same age (0·05 kg/mB; -0·04 to 0·15, p=0·3), but widen fastest in boys, especially for FMI, in which there was over an 11 times increase in the inequality from age 7 years of 0·05kg/mB (95% CI -0·04 to 0·15) to 0·62 kg/mB at 17 years (0·42 to 0·82). Inequalities for the IMD were similar to income, and persisted at age 17 years independent of family socioeconomic position.

INTERPRETATION

Childhood and adolescence is an important period to address inequalities in body composition, as they emerge and widen. Policies should consider FFM as well as FM, and inequalities in the environment.

FUNDING

Medical Research Council, Economic and Social Research Council.

Prevalence and early-life determinants of mid-life multimorbidity: evidence from the 1970 British birth cohort

BACKGROUND

We sought to: [1] estimate the prevalence of multimorbidity at age 46-48 in the 1970 British Cohort Study-a nationally representative sample in mid-life; and [2] examine the association between early-life characteristics and mid-life multimorbidity.

METHOD

A prospective longitudinal birth cohort of a community-based sample from the 1970 British Cohort Study (BCS70). Participants included all surviving children born in mainland Britain in a single week in April 1970; the analytical sample included those with valid data at age 46-48 (n = 7951; 2016-2018). The main outcome was multimorbidity, which was operationalised as a binary indicator of two or more long-term health conditions where at least one of these conditions was of physical health. It also included symptom complexes (e.g., chronic pain), sensory impairments, and alcohol problems.

RESULTS

Prevalence of mid-life multimorbidity was 33.8% at age 46-48. Those with fathers from unskilled social occupational class (vs professional) at birth had 43% higher risk of mid-life multimorbidity (risk ratio = 1.43, 95% confidence interval 1.15 to 1.77). After accounting for potential child and family confounding, an additional kilogram of birthweight was associated with 10% reduced risk of multimorbidity (risk ratio = 0.90, 95% confidence interval 0.84 to 0.96); a decrease of one body mass index point at age 10 was associated with 3% lower risk (risk ratio = 1.03, 95% confidence interval 1.01 to 1.05); one standard deviation higher cognitive ability score at age 10 corresponded to 4% lower risk (risk ratio = 0.96, 95% confidence interval 0.91 to 1.00); an increase of one internalising problem at age 16 was equated with 4% higher risk (risk ratio = 1.04, 95% confidence interval 1.00 to 1.08) and of one externalising problem at age 16 with 6% higher risk (risk ratio = 1.06, 1.03 to 1.09).

CONCLUSION

Prevalence of multimorbidity was high in mid-life (33.8% at age 46-48) in Britain. Potentially modifiable early-life exposures, including early-life social circumstances, cognitive, physical and emotional development, were associated with elevated risk of mid-life multimorbidity.

Self-reported and mother-rated personality traits at age 16 are associated with cognitive function measured concurrently and 30 years later

BACKGROUND

Models of personality and health suggest that personality contributes to health outcomes across adulthood. Personality traits, such as neuroticism and conscientiousness, have long-term predictive power for cognitive impairment in older adulthood, a critical health outcome. Less is known about whether personality measured earlier in life is also associated with cognition across adulthood prior to dementia.

METHODS

Using data from the British Cohort Study 1970 (N = 4218; 58% female), the current research examined the relation between self-reported and mother-rated personality at age 16 and cognitive function concurrently at age 16 and cognitive function measured 30 years later at age 46, and whether these traits mediate the relation between childhood social class and midlife cognition.

RESULTS

Self-reported and mother-rated conscientiousness at age 16 were each associated with every cognitive measure at age 16 and most measures at age 46. Self-reported openness was likewise associated with better cognitive performance on all tasks at age 16 and prospectively predicted age 46 performance (mothers did not rate openness). Mother-rated agreeableness, but not self-reported, was associated with better cognitive performance at both time points. Adolescent personality mediated the relation between childhood social class and midlife cognitive function.

CONCLUSIONS

The current study advances personality and cognition by showing that (1) adolescent personality predicts midlife cognition 30 years later, (2) both self-reports and mother-ratings are important sources of information on personality associated with midlife cognition, and (3) adolescent personality may be one pathway through which the early life socioeconomic environment is associated with midlife cognition.

Socioeconomic inequalities in children's weight, height and BMI trajectories in Norway

Studies exploring when social inequalities in body mass index (BMI) and its composites emerge and how these evolve with age are limited. Thus, this study explored parental income and education related inequalities in children's weight, height, weight velocity and body mass index among Norwegian children from 1 month to 8 years. The study population included 59,927 family/children pairs participating in the Norwegian Mother, Father, and Child Cohort Study. Growth was modelled using the Jenss-Bayley model and linear mixed effects analyses were conducted. Maternal and paternal educational differences in children's weight and BMI trajectories emerged during infancy, continuing to age 8 years. Parental income-related inequalities in children's weight were observed from the age of 1 month to 4 years for maternal and up to 1 year for paternal income-related differences but then disappeared. Parental income-related inequalities in child's BMI were observed from 18 months to 8 years for maternal income, and from 9 months to 8 years for paternal income-related differences. These results suggest that social inequalities in children's BMI present early in infancy and continue to 8 years of age. The inequalities sometimes differed by indicator of socioeconomic position used. Interventions to combat these inequalities early in life are, thus needed.

Socioeconomic inequalities across life and premature mortality from 1971 to 2016: findings from three British birth cohorts born in 1946, 1958 and 1970

INTRODUCTION

Disadvantaged socioeconomic position (SEP) in early and adult life has been repeatedly associated with premature mortality. However, it is unclear whether these inequalities differ across time, nor if they are consistent across different SEP indicators.

METHODS

British birth cohorts born in 1946, 1958 and 1970 were used, and multiple SEP indicators in early and adult life were examined. Deaths were identified via national statistics or notifications. Cox proportional hazard models were used to estimate associations between ridit scored SEP indicators and all-cause mortality risk-from 26 to 43 years (n=40 784), 26 to 58 years (n=35 431) and 26 to 70 years (n=5353).

RESULTS

More disadvantaged SEP was associated with higher mortality risk-magnitudes of association were similar across cohort and each SEP indicator. For example, HRs (95% CI) from 26 to 43 years comparing lowest to highest paternal social class were 2.74 (1.02 to 7.32) in 1946c, 1.66 (1.03 to 2.69) in 1958c, and 1.94 (1.20 to 3.15) in 1970c. Paternal social class, adult social class and housing tenure were each independently associated with mortality risk.

CONCLUSIONS

Socioeconomic circumstances in early and adult life show persisting associations with premature mortality from 1971 to 2016, reaffirming the need to address socioeconomic factors across life to reduce inequalities in survival to older age.

Inequality in hospitalization due to non-communicable diseases in Sweden: Age-cohort analysis of the Uppsala Birth Cohort Multigenerational Study

We aimed to investigate cohort differences in age trajectories of hospitalization due to non-communicable conditions, and if these varied by paternal socioeconomic position. We used the Uppsala Birth Cohort Multigenerational Study—including virtually complete information on medical diagnoses.

Our sample constituted 28,448 individuals (103,262 observations). The outcome was five-year prevalence of hospitalization due to major non-communicable conditions in 1989–2008. The exposures were age (19–91), year-of-birth (1915–1929; 1938–1972), gender (man vs woman), and parental socioeconomic position (low, medium, and high). We used multilevel logit models to examine associations between exposures and the hospitalization outcome.

Younger cohorts had a higher prevalence of hospitalization at overlapping ages than those born earlier, with inter-cohort differences emerging from early-adulthood and increasing with age. For instance, at age 40 predicted probability of hospitalization increased across birth-cohorts—from 1.2% (born in 1948-52) to 2.0% (born in 1963-67)—whereas at age 50 it was 2.9% for those born in 1938-42 compared with 4.6% among participants born in 1953-57. Those with medium and low socioeconomic position had 13.0% and 20.0% higher odds of experiencing hospitalization during the observation period, respectively—when age, year-of-birth and gender were accounted for.

We found that no progress was made in reducing the socioeconomic inequalities in hospitalization across cohorts born between 1915 and 1972. Hence, more effective policies and interventions are needed to reduce the overall burden of morbidity—particularly among the most vulnerable.

•

What is already known on this subject?

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The evidence on trends in morbidity in Sweden is mainly cross-sectional and focused on individual conditions.

•

Rates of various indicators of morbidity (e.g. poor mobility, psychological distress, disability) have increased over time.

•

What this study adds.

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Successively younger birth cohorts had a higher prevalence of hospitalization, with differences emerging in early-adulthood.

•

Those in medium and low parental socioeconomic position (vs high) had 13% and 20% higher odds of hospitalization.

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No progress was made in reducing the socioeconomic inequalities across cohorts born between 1915 and 1972.

Body mass index, prudent diet score and social class across three generations: evidence from the Hertfordshire Intergenerational Study

BACKGROUND

Studies describing body mass index (BMI) and prudent diet score have reported that they are associated between parents and children. The Hertfordshire Intergenerational Study, which contains BMI, diet and social class information across three generations, provides an opportunity to consider the influence of grandparental and parental BMI and prudent diet score across multiple generations, and the influence of grandparental and parental social class on child BMI.

METHODS

Linear regressions examining the tracking of adult BMI and prudent diet score across three generations (grandparent (F0), parent (F1) and child (F2)) were run from parent to child and from grandparent to grandchild. Linear mixed models investigated the influence of F0 and F1 BMI or prudent diet score on F2 BMI and prudent diet score. Linear regressions were run to determine whether social class and prudent diet score of parents and grandparents influenced the BMI of children and grandchildren.

RESULTS

BMI was significantly associated across each generational pair and from F0 to F1 in multilevel models. Prudent diet score was significantly positively associated between grandparents and grandchildren. Lower grandparental and parental social class had a significantly positive association with F2 BMI (F0 low social class: b=1.188 kg/m2, 95% CI 0.060 to 2.315, p=0.039; F1 middle social class: b=2.477 kg/m2, 95% CI 0.726 to 4.227, p=0.006).

CONCLUSION

Adult BMI tracks across generations of the Hertfordshire Intergenerational Study, and child BMI is associated with parental and grandparental social class. The results presented here add to literature supporting behavioural and social factors in the transmission of BMI across generations.

Intergenerational social mobility and body mass index trajectories - A follow-up study from Finland

Evidence remains unclear on how intergenerational social mobility is associated with body mass index (BMI) and its long-term changes. Our study identified BMI trajectories from middle to older age by intergenerational social mobility groups and stratified the analyses by gender and two birth cohorts (birth years 1940‒1947 and 1950–1962). We used questionnaire-based cohort data that consists of four survey phases: 2000–2002, 2007, 2012, and 2017. In Phase 1, participants were 40–60-year-old employees of the City of Helsinki, Finland. Our analytical sample consisted of 6,971 women and 1,752 men. Intergenerational social mobility was constructed based on self-reported parental and own education—both divided into high and low—yielding four groups: stable high socioeconomic position (SEP) (high-high), upward social mobility (low-high), downward social mobility (high-low), and stable low SEP (low-low). BMI was calculated from self-reported height and weight from all four phases. Using mixed-effects linear regression, we found increasing BMI trajectories in all four social mobility groups until the age of 65. Women and men with stable high SEP had lower BMI trajectories compared to those with stable low SEP. In the younger birth cohort, women with upward social mobility had a lower BMI trajectory than women with stable low SEP. Additionally, women and men with downward social mobility had higher BMI trajectories than those with stable high SEP. In the older birth cohort, however, the BMI trajectories of upward and downward social mobility groups were somewhat similar and settled between the BMI trajectories of stable high and stable low SEP groups. Our results indicate that the associations between intergenerational social mobility and BMI may depend on gender and birth cohort. Nevertheless, to reduce socioeconomic inequalities in unhealthy weight gain, obesity prevention actions that focus on people who are likely to remain in low SEP might be worthwhile.

•

Few studies exist on social mobility and long-term body mass index (BMI) changes.

•

Rising BMI trajectories were found in all social mobility groups.

•

Stable low socioeconomic position (SEP) was related to higher BMI trajectories.

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Stable high SEP and upward social mobility may protect from excessive weight gain.

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Social mobility–BMI associations differed by gender and birth cohort.

Socioeconomic inequalities in blood pressure: co-ordinated analysis of 147,775 participants from repeated birth cohort and cross-sectional datasets, 1989 to 2016

BACKGROUND

High blood pressure (BP) is a key modifiable determinant of cardiovascular disease and a likely determinant of other adverse health outcomes. While socioeconomic inequalities in BP are well documented, it remains unclear (1) how these inequalities have changed across time, given improvements over time in the detection and treatment of high BP (hypertension); (2) whether BP inequalities are present below and above hypertension treatment thresholds; and (3) whether socioeconomic position (SEP) across life has cumulative effects on BP. We sought to address these gaps using evidence from two complementary sources: birth cohort and repeated cross-sectional datasets.

METHODS

We used three British birth cohort studies-born in 1946, 1958, and 1970-with BP measured at 43-46 years (in 1989, 2003, and 2016), and 21 repeated cross-sectional datasets-the Health Survey for England (HSE), with BP measured among adults aged ≥ 25 years (1994-2016). Adult education attainment was used as an indicator of SEP in both datasets; childhood father's social class was used as an alternative indicator of (early life) SEP in cohorts. Adjusting for the expected average effects of antihypertensive medication use, we used linear regression to quantify SEP differences in mean systolic BP (SBP), and quantile regression to investigate whether inequalities differed across SBP distributions-below and above hypertension treatment thresholds.

RESULTS

In both datasets, lower educational attainment was associated with higher SBP, with similar absolute magnitudes of inequality across the studied period. Differences in SBP by education (Slope Index of Inequality) based on HSE data were 3.0 mmHg (95% CI 1.8, 4.2) in 1994 and 4.3 mmHg (2.3, 6.3) in 2016. Findings were similar for diastolic BP (DBP) and survey-defined hypertension. Inequalities were found across the SBP distribution in both datasets-below and above the hypertension threshold-yet were larger at the upper tail; in HSE, median SBP differences were 2.8 mmHg (1.7, 3.9) yet 5.6 mmHg (4.9, 6.4) at the 90th quantile. Adjustment for antihypertensive medication use had little impact on the magnitude of inequalities; in contrast, associations were largely attenuated after adjustment for body mass index. Finally, cohort data suggested that disadvantage in early and adult life had cumulative independent associations with BP: cohort-pooled differences in SBP were 5.0 mmHg (3.8, 6.1) in a score combining early life social class and own education, yet were 3.4 mmHg (2.4, 4.4) for education alone.

CONCLUSION

Socioeconomic inequalities in BP have persisted from 1989 to 2016 in Britain/England, despite improved detection and treatment of high BP. To achieve future reductions in BP inequalities, policies addressing the wider structural determinants of high BP levels are likely required, particularly those curtailing the obesogenic environment-targeting detection and treatment alone is unlikely to be sufficient.

Effects of body mass index on relationship status, social contact and socio-economic position: Mendelian randomization and within-sibling study in UK Biobank

BACKGROUND

We assessed whether body mass index (BMI) affects social and socio-economic outcomes.

METHODS

We used Mendelian randomization (MR), non-linear MR and non-genetic and MR within-sibling analyses, to estimate relationships of BMI with six socio-economic and four social outcomes in 378 244 people of European ancestry in UK Biobank.

RESULTS

In MR of minimally related individuals, higher BMI was related to higher deprivation, lower income, fewer years of education, lower odds of degree-level education and skilled employment. Non-linear MR suggested both low (bottom decile, <22 kg/m2) and high (top seven deciles, >24.6 kg/m2) BMI, increased deprivation and reduced income. Non-genetic within-sibling analysis supported an effect of BMI on socio-economic position (SEP); precision in within-sibling MR was too low to draw inference about effects of BMI on SEP. There was some evidence of pleiotropy, with MR Egger suggesting limited effects of BMI on deprivation, although precision of these estimates is also low. Non-linear MR suggested that low BMI (bottom three deciles, <23.5 kg/m2) reduces the odds of cohabiting with a partner or spouse in men, whereas high BMI (top two deciles, >30.7 kg/m2) reduces the odds of cohabitation in women. Both non-genetic and MR within-sibling analyses supported this sex-specific effect of BMI on cohabitation. In men only, higher BMI was related to lower participation in leisure and social activities. There was little evidence that BMI affects visits from friends and family or having someone to confide in.

CONCLUSIONS

BMI may affect social and socio-economic outcomes, with both high and low BMI being detrimental for SEP, although larger within-family MR studies may help to test the robustness of MR results in unrelated individuals. Triangulation of evidence across MR and within-family analyses supports evidence of a sex-specific effect of BMI on cohabitation.

The politics of frailty

The world population is ageing because of falling fertility and improved life expectancy. Knowing this has not helped governments develop sustainable health and care policies because the underlying causes and impacts of population ageing remain poorly understood. Planning using only population age structure does not account for uneven geographical distribution of older people, their health characteristics, functional needs or lived experiences. English National Health Service (NHS) policy has previously focused on arbitrary age segmentation, failing to capture the origins of cumulative disease and functional burden and missing the opportunity to incorporate wider determinants of health into prevention of poor-quality ageing. This is despite growing international evidence that adults living in places with low per capita income and educational attainment experience a higher burden of age-related disease. Lack of a credible ageing narrative and good quality population health data have contributed to a focus on single disease prevention, rather than life course disease aggregation and its personal impacts. However, a fully explicated health and care narrative incorporating frailty does now give some cause for optimism. In 2017, England became the first country to characterise and systematically identify frailty as a long-term treatable health condition. This was coincident with a UK Government's Industrial Strategy targeting societal ageing. In 2019, the English NHS published a funded long-term plan including a major programme focused on ageing well. Policy makers, health leaders and clinicians must not squander these opportunities but instead pursue frailty prevention and intervention to improve the quality of population ageing.

Weight gain and changes in nutritional status of Brazilian adults after 20 years of age: a time-trend analysis (2006-2012)

OBJECTIVE

To analyze weight gain (WG) and change in nutritional status (NS) after the age of 20 years in the Brazilian adult population between 2006 and 2012.

METHODS

Time series using seven surveys from the Surveillance of Risk and Protective Factors for Chronic Diseases by Telephone Survey (VIGITEL). The analyses were stratified by region, age, sex and education, considering the sampling weights and complex design. In addition, relative weight change (RWC) in the period was determined for each category of independent variables using linear regression models.

RESULTS

Analyses showed an increase in WG after 20 years in two vectors: by survey year and age group, where the increase was higher in women. From 2006 to 2012, individuals 25-29 years old (women: RWC = 70%; βyear = 0.54 kg/year) and 30-34 years old (women: RWC = 56%; βyear = 0.57 kg/year) showed greater RWC. In 2012, the higher WG occurred in the age groups of 21-24 and 25-29 years old. Regarding the change in NS, individuals who were overweight at 20 years had a higher probability of remaining in this condition (or shifting to obesity) over time. However, among those who had a normal weight, the probability of not becoming overweight or obese was > 80%, independently of sex.

CONCLUSION

The Brazilian population displayed progressive WG in adulthood, especially in the first decade after the age of 20, in addition to the period effect. On the other hand, individuals with normal weight in their 20s tended to maintain the same condition.

Why young women gain weight: A narrative review of influencing factors and possible solutions

Significant weight gain occurs in women during young adulthood, which increases risk of diseases such as diabetes, cardiovascular disease, and many cancers. This review aims to inform future individually targeted weight gain prevention programmes and summarizes possible targets: key life events, mediators that influence energy intake and physical activity levels, and moderators that could identify groups of women at greatest risk. Life events affecting weight include pregnancy and motherhood, smoking cessation, marriage and cohabiting, attending university, and possibly bereavement. Research has identified successful methods for preventing weight gain associated with pregnancy and motherhood, which could now be used in practice, but evidence is inconclusive for preventing weight gain around other life events. Weight gain is mediated by lack of knowledge and skills around food and nutrition, depression, anxiety, stress, satiety, neural responses, and possibly sleep patterns and premenstrual cravings. A paucity of research exists into altering these to limit weight gain. Moderators include socioeconomic status, genetics, personality traits, and eating styles. More research is required to identify at-risk females and engage them in weight gain prevention. There is a need to address evidence gaps highlighted and implement what is currently known to develop effective strategies to limit weight gain in young women.

Association of Parental Socioeconomic Status and Newborn Telomere Length

IMPORTANCE

Low socioeconomic status is associated with higher all-cause mortality and risks for aging-related diseases. Biological aging is a potential process underlying health conditions related to social disadvantages, which may be present from birth onward.

OBJECTIVE

To evaluate the association of parental socioeconomic status with telomere length (TL) at birth, a marker of biological aging.

DESIGN, SETTING, AND PARTICIPANTS

This prospective birth cohort study was conducted among 1504 mother-newborn pairs in Belgium recruited between February 1, 2010, and July 1, 2017.

EXPOSURES

Parental socioeconomic measures, including maternal educational level, occupation, paternal educational level, and neighborhood income based on median annual household income.

MAIN OUTCOMES AND MEASURES

Mean relative TL was measured in cord blood and placental tissue. By constructing a principal component, an integrative socioeconomic measure was derived that integrates parental socioeconomic status and neighborhood income. Multivariable adjusted regression analyses were performed to associate the integrative socioeconomic measure and TL at birth.

RESULTS

In 1026 newborns (517 boys; mean [SD] gestational age, 39.2 [1.4] weeks), a higher socioeconomic status was associated with longer cord blood TL and placental TL. Each unit increment in the integrative socioeconomic status measure was associated with 2.1% (95% CI, 0.9%-3.4%; P < .001) longer cord blood TL in boys, while no association was observed for girls (0.5% longer cord blood TL; 95% CI, -0.9% to 1.8%; P = .50). The sex-specific socioeconomic status interaction revealed a stronger association in boys compared with newborn girls (1.6%; 95% CI, 0.02%-3.3%; P = .047 for interaction). In placental tissue, higher socioeconomic status was associated with 1.8% (95% CI, 0.3%-3.3%; P = .02) longer TL in newborn boys but not in girls (0.4% longer TL; 95% CI, -1.2% to 2.0%; P = .63). For placental tissue, no sex and socioeconomic status interaction on TL was observed (1.4%; 95% CI, -0.5% to 3.4%; P = .16 for interaction).

CONCLUSIONS AND RELEVANCE

This study suggests that parental socioeconomic status is associated with newborn TL, especially in boys. The results indicate that familial social economic factors are associated with the potential cellular longevity of the next generation, with a potential higher transgenerational vulnerability for newborn boys.

Distinct patterns of socio-economic disparities in child-to-adolescent BMI trajectories across UK ethnic groups: A prospective longitudinal study

BACKGROUND

In many high-income countries, body mass index (BMI)/obesity levels are inversely associated with socio-economic position (SEP). Little is known whether socio-economic patterns in BMI trajectories throughout childhood differ by ethnicity, especially in the United Kingdom.

OBJECTIVES

To investigate socio-economic disparities in child-to-adolescent BMI trajectories and risks of overweight and obesity during adolescence across ethnic groups.

METHODS

Mixed-effects fractional polynomial and multinomial regression models were applied to estimate socio-economic differences in BMI trajectories (3-14 years) and risk of overweight/obesity at 14 years, respectively, in the UK Millennium Cohort Study (n = 15 996). Analysis was stratified by ethnicity.

RESULT

Poverty was associated with higher BMI in children of White and South Asian origins, with a small difference at 3 years, which widened with age to 0.75 kg/m2 (95% CI, 0.59-0.91) and 0.77 kg/m2 (0.26-1.27) at 14 years for the White and South Asian groups, respectively. There was a reverse income-BMI association in children of Black (African-Caribbean) origin with the poverty group having a lower BMI (-0.37 kg/m2 [-0.71 to -0.04] at 5 years; -0.95 kg/m2 [-1.79 to -0.11] at 14 years). These patterns also presented with maternal education as a SEP indicator and for obesity at 14 years.

CONCLUSIONS

Socio-economic advantage may not be universally associated with lower BMI, which should be considered when planning obesity interventions. The positive SEP-BMI association in children of Black origin requires replication and merits further investigation into underpinning mechanisms.

Is it time to stop sweeping data cleaning under the carpet? A novel algorithm for outlier management in growth data

All data are prone to error and require data cleaning prior to analysis. An important example is longitudinal growth data, for which there are no universally agreed standard methods for identifying and removing implausible values and many existing methods have limitations that restrict their usage across different domains. A decision-making algorithm that modified or deleted growth measurements based on a combination of pre-defined cut-offs and logic rules was designed. Five data cleaning methods for growth were tested with and without the addition of the algorithm and applied to five different longitudinal growth datasets: four uncleaned canine weight or height datasets and one pre-cleaned human weight dataset with randomly simulated errors. Prior to the addition of the algorithm, data cleaning based on non-linear mixed effects models was the most effective in all datasets and had on average a minimum of 26.00% higher sensitivity and 0.12% higher specificity than other methods. Data cleaning methods using the algorithm had improved data preservation and were capable of correcting simulated errors according to the gold standard; returning a value to its original state prior to error simulation. The algorithm improved the performance of all data cleaning methods and increased the average sensitivity and specificity of the non-linear mixed effects model method by 7.68% and 0.42% respectively. Using non-linear mixed effects models combined with the algorithm to clean data allows individual growth trajectories to vary from the population by using repeated longitudinal measurements, identifies consecutive errors or those within the first data entry, avoids the requirement for a minimum number of data entries, preserves data where possible by correcting errors rather than deleting them and removes duplications intelligently. This algorithm is broadly applicable to data cleaning anthropometric data in different mammalian species and could be adapted for use in a range of other domains.

The Relationship of Early-Life Adversity With Adulthood Weight and Cardiometabolic Health Status in the 1946 National Survey of Health and Development

OBJECTIVE

Evidence linking early-life adversity with an adverse cardiometabolic profile in adulthood is equivocal. This study investigates early-life adversity in relation to weight and cardiometabolic health status at ages 60 to 64 years.

METHODS

We included 1059 individuals from the 1946 National Survey of Health and Development. Data on adversity between ages 0 to 15 years were used to create a cumulative childhood psychosocial adversity score and a socioeconomic adversity score. Cardiometabolic and weight/height data collected at ages 60 to 64 years were used to create four groups: metabolically healthy normal weight, metabolically unhealthy normal weight, metabolically healthy overweight/obese, and metabolically unhealthy overweight/obese. Associations between the two exposure scores and weight/health status were examined using multinomial logistic regression, with adjustment for sex and age at the outcome visit.

RESULTS

Sixty-two percent of normal-weight individuals were metabolically healthy, whereas only 34% of overweight/obese individuals were metabolically healthy. In a mutually adjusted model including both exposure scores, a psychosocial score of ≥3 (compared with 0) was associated with increased risk of being metabolically unhealthy (compared with healthy) in both normal-weight adults (relative risk = 2.49; 95% confidence interval = 0.87-7.13) and overweight/obese adults (1.87; 0.96-3.61). However, the socioeconomic adversity score was more strongly related to metabolic health status in overweight/obese adults (1.60; 0.98-2.60) than in normal-weight adults (0.95; 0.46-1.96).

CONCLUSIONS

Independently of socioeconomic adversity, psychosocial adversity in childhood may be associated with a poor cardiometabolic health profile, in both normal-weight and overweight/obese adults.

How youth cognitive and sociodemographic factors relate to the development of overweight and obesity in the UK and the USA: a prospective cross-cohort study of the National Child Development Study and National Longitudinal Study of Youth 1979

OBJECTIVES

We investigated how youth cognitive and sociodemographic factors are associated with the aetiology of overweight and obesity. We examined both onset (who is at early risk for overweight and obesity) and development (who gains weight and when).

DESIGN

Prospective cohort study.

SETTING

We used data from the US National Longitudinal Study of Youth 1979 (NLSY) and the UK National Child Development Study (NCDS); most of both studies completed a cognitive function test in youth.

PARTICIPANTS

12 686 and 18 558 members of the NLSY and NCDS, respectively, with data on validated measures of youth cognitive function, youth socioeconomic disadvantage (eg, parental occupational class and time spent in school) and educational attainment. Height, weight and income data were available from across adulthood, from individuals' 20s into their 50s.

PRIMARY AND SECONDARY OUTCOME MEASURES

Body mass index (BMI) for four time points in adulthood. We modelled gain in BMI using latent growth curve models to capture linear and quadratic components of change in BMI over time.

RESULTS

Across cohorts, higher cognitive function was associated with lower overall BMI. In the UK, 1 SD higher score in cognitive function was associated with lower BMI (β=-0.20, 95% CI -0.33 to -0.06 kg/m²). In America, this was true only for women (β=-0.53, 95% CI -0.90 to -0.15 kg/m²), for whom higher cognitive function was associated with lower BMI. In British participants only, we found limited evidence for negative and positive associations, respectively, between education (β=-0.15, 95% CI -0.26 to -0.04 kg/m²) and socioeconomic disadvantage (β=0.33, 95% CI 0.23 to 0.43 kg/m²) and higher BMI. Overall, no cognitive or socioeconomic factors in youth were associated with longitudinal changes in BMI.

CONCLUSIONS

While sociodemographic and particularly cognitive factors can explain some patterns in individuals' overall weight levels, differences in who gains weight in adulthood could not be explained by any of these factors.

Socioeconomic position and body composition across the life course: a systematic review protocol

INTRODUCTION

The relation between socioeconomic position (SEP) and obesity measured by body mass index (BMI) has been extensively reviewed, but there is less research on the association between SEP and body composition. Fat distribution and muscle quality have been linked to adverse health outcomes such as cardiovascular disease, diabetes and poor physical capability. There is some evidence of secular changes in body composition with increasing fat-mass and reducing muscle quantity and strength, but it is unclear whether there have been secular changes in social inequalities in body composition. The aim is to perform a systematic review of the existing literature on the association between SEP and body composition and to explore any secular changes.

METHODS

The systematic review will be carried out according to PRISMA guidelines. An electronic search of MEDLINE and Embase Classic + Embase will be conducted using OvidSP as the database interface, as well as SPORTDiscus using EBSCO. Two independently working reviewers will initially screen abstracts to exclude papers that are clearly ineligible, followed by a full-text screening to exclude papers not meeting all inclusion criteria. Any disagreements will be resolved through discussion. Data extraction and quality assessment of eligible papers will be carried out by 2 reviewers using a standardised form. The reference lists of identified papers will be searched for additional papers. Original studies in the English language, which examine the association between SEP at any age and body composition at the same or later age will be included if they use any recognised measures of SEP (e.g. income, occupation, over-crowding) and a recognised measure of body composition (total, proportional or location of fat mass and fat-free mass, using any appropriate methods, excluding anthropometry). Due to expected heterogeneity, a narrative synthesis is expected, with a descriptive summary to be provided in tables. If there is consistency in reporting of associations, a random-effects meta-analysis will be used to provide an overall summary estimate.

DISCUSSION

The results of the review will summarise the existing evidence on social inequalities in body composition. Findings will identify gaps in knowledge and where further research is required.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019119937.

Health Challenges of the Pacific Region: Insights From History, Geography, Social Determinants, Genetics, and the Microbiome

The Pacific region, also referred to as Oceania, is a geographically widespread region populated by people of diverse cultures and ethnicities. Indigenous people in the region (Melanesians, Polynesians, Micronesians, Papuans, and Indigenous Australians) are over-represented on national, regional, and global scales for the burden of infectious and non-communicable diseases. Although social and environmental factors such as poverty, education, and access to health-care are assumed to be major drivers of this disease burden, there is also developing evidence that genetic and microbiotic factors should also be considered. To date, studies investigating genetic and/or microbiotic links with vulnerabilities to infectious and non-communicable diseases have mostly focused on populations in Europe, Asia, and USA, with uncertain associations for other populations such as indigenous communities in Oceania. Recent developments in personalized medicine have shown that identifying ethnicity-linked genetic vulnerabilities can be important for medical management. Although our understanding of the impacts of the gut microbiome on health is still in the early stages, it is likely that equivalent vulnerabilities will also be identified through the interaction between gut microbiome composition and function with pathogens and the host immune system. As rapid economic, dietary, and cultural changes occur throughout Oceania it becomes increasingly important that further research is conducted within indigenous populations to address the double burden of high rates of infectious diseases and rapidly rising non-communicable diseases so that comprehensive development goals can be planned. In this article, we review the current knowledge on the impact of nutrition, genetics, and the gut microbiome on infectious diseases in indigenous people of the Pacific region.