Physical activity in adolescence: cross-national comparisons of levels, distributions and disparities across 52 countries

Introduction: Despite global concerns regarding physical inactivity, limited cross-national evidence exists to compare adolescents’ physical activity participation. We analysed 52 high- and low-middle income countries, with activity undertaken inside and outside of school in 2015. We investigated gender- and socioeconomic-disparities, and additionally examined correlations with country-level indices of physical education (PE) curriculum time allocation, wealth, and income inequality. / Methods: We used the Programme for International Student Assessment (PISA), a nationally representative cross-sectional survey of 15-year-olds (N=347,935). Students reported average attendance (days/week) in PE classes, and the days/week engaged in moderate activity (MPA) and vigorous activity (VPA) outside of school. Both the mean and distributions of outcomes were evaluated, as were gender- and socioeconomic-disparities. Pearson’s correlations (r) between the physical activity outcomes and PE curriculum time allocation, wealth (indexed by GDP) and income inequality (indexed by the Gini coefficient) were calculated. / Results: Activity levels inside and outside of school were higher in Eastern Europe than Western Europe, the Americas, and the Middle East/North Africa. Comparisons of average levels masked potentially important differences in distributions. For example, activity levels inside school showed a bimodal distribution in the US (mean PE class attendance 2.4 days/week; 41.3%, 6.3% and 33.1% of students attended PE classes on 0, 2 and 5 days/week respectively). In contrast, most other countries exhibited more centrally shaped distributions. Pro-male and pro-high socioeconomic disparities were modest for participation inside school, but higher for MPA and VPA outside of school. The magnitude of these also differed markedly by country. Activity in school was weakly positively correlated with PE curriculum time allocation (r=0.33); activity outside of school was strongly negatively correlated with income inequality (e.g. r=-0.69 for MPA). / Conclusion: Our findings reveal extensive cross-country differences in adolescents’ physical activity; in turn, these highlight policy areas that could ultimately improve global adolescent health, such as the incorporation of minimum country-level PE classes, and the targeting of gender- and socioeconomic- disparities in activity conducted outside of school. Our findings also highlight the utility of educational databases such as PISA for use in global population health research

Changes in the body mass index and blood pressure association across time: Evidence from multiple cross-sectional and cohort studies

Although body mass index (BMI) is considered a key determinant of high blood pressure, its importance may differ over time and by age group. We utilised separate data sources to investigate temporal changes in this association: 23 independent (newly sampled), repeated cross-sectional studies (Health Survey for England (HSE)) at ≥25 years (1994-2018; N = 126,742); and three British birth cohorts at 43-46 years (born 1946, 1958, and 1970; N = 18,657). In HSE, associations were weaker in more recent years, with this trend most pronounced amongst older adults. After adjustment for sex, anti-hypertensive treatment and education, the mean difference in systolic blood pressure (SBP) per 1 kg/m2 increase in BMI amongst adults ≥55 years was 0.75 mmHg (95%CI: 0.60-0.90) in 1994, 0.66 mmHg (0.46-0.85) in 2003, and 0.53 mmHg (0.35-0.71) in 2018. In the 1958 and 1970 cohorts, BMI and SBP associations were of similar magnitude yet weaker in the 1946 cohort, potentially due to differences in blood pressure measurement device. Quantile regression analyses suggested that associations between BMI and SBP were present both below and above the hypertension threshold. A weaker association between BMI and blood pressure may partly offset the public health impacts of increasing obesity prevalence. However, despite sizable increases in use of antihypertensive medication, BMI remains positively associated with SBP in all ages. Our findings highlight the need to tackle non-medical factors such as population diet which influence both BMI and blood pressure and the utility of using multiple datasets to obtain robust inferences on trends in risk factor-outcome associations across time

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

Associations of childcare type, age at start, and intensity with body mass index trajectories from 10 to 42 years of age in the 1970 British Cohort Study

Background: Attending childcare is related to greater childhood obesity risk, but there are few long-term follow-up studies. We aimed to examine the associations of childcare type, age at start, and intensity with body mass index body mass index (BMI) trajectories from ages 10 to 42 years. Methods: The sample comprised 8234 individuals in the 1970 British Cohort Study, who had data on childcare attendance (no, yes), type (formal, informal), age at start (4-5, 3-3.99, 0-2.99 years old), and intensity (1, 2, 3, 4-5 days/week) reported at age 5 years and 32 563 BMI observations. Multilevel linear spline models were used to estimate the association of each exposure with the sample-average BMI trajectory, with covariate adjustment. A combined age at start and intensity exposure was also examined. Results: Attending vs not attending and the type of childcare (none vs formal/informal) were not strongly related to BMI trajectories. Among participants who attended childcare 1 to 2 days a week, those who started when 3 to 3.99 years old had a 0.197 (−0.004, 0.399) kg/m2 higher BMI at age 10 years than those who started when 4 to 5 years old, and those who started when 0 to 2.99 years old had a 0.289 (0.049, 0.529) kg/m2 higher BMI. A similar dose-response pattern for intensity was observed when holding age at start constant. By age 42 years, individuals who started childcare at age 0 to 2.99 years and attended 3 to 5 days/week had a 1.356 kg/m2 (0.637, 2.075) higher BMI than individuals who started at age 4 to 5 years and attended 1 to 2 days/week. Conclusions: Children who start childcare earlier and/or attend more frequently may have greater long-term obesity risk

Bullying victimisation in adolescence: prevalence and inequalities by gender, socioeconomic status and academic performance across 71 countries

Background: Bullying victimisation is of global importance due to its long-term negative consequences. We examined the prevalence of victimisation and its inequalities in 15-year-olds across 71 countries. Methods: Data were from the Programme for International Student Assessment (March-August 2018). Students reported frequencies of relational, physical, and verbal victimisation during the last 12 months, which were analysed separately and combined into a total score. Prevalence of frequent victimisation (> a few times a month) was estimated, followed by mean differences in total score by gender, wealth and academic performance quintiles in each country. Meta-analyses were used to examine country differences. Findings: Of 421,437 students included, 113,602 (30·4%) experienced frequent victimisation, yet this varied by country-from 9·3% (Korea) to 64·8% (Philippines). Verbal and relational victimisation were more frequent (21·4%, 20.9%, respectively) than physical victimisation (15·2%). On average, boys (vs girls +0·23SD, 95%CI: 0·22-0·24), students from the lowest wealth (vs highest +0·09SD, 0·08-0·10) and with lowest academic performance (vs highest +0·49SD, 0·48-0·50) had higher scores. However, there was substantial between-country heterogeneity in these associations (I2=85%-98%). Similar results were observed for subtypes of victimisation-except relational victimisation, where gender inequalities were smaller. Interpretation: Globally, bullying victimisation was high, although the size, predominant subtype and strength of associations with risk factors varied by country. The large cross-country differences observed require further replication and empirical explanation, and suggest the need to and the large scope for reducing bullying victimisation and its inequity in the future. Funding: Japan Foundation for Pediatric Research

Does an elite education benefit health? Findings from the 1970 British Cohort Study

Background Attending private school or a higher status university is thought to benefit future earnings and occupational opportunities. We examined whether these measures were beneficially related to health and selected health-related behaviours in midlife. Methods Data were from up to 9799 participants from the 1970 British birth Cohort Study. The high school attended (private, grammar, or state) was ascertained at 16 years, and the university attended reported at 42 years (categorised as either a higher (Russell Group institution) or normal status institutions). Self-reported health, limiting illness, and BMI were reported at 42 years, along with television viewing, take-away meal consumption, physical inactivity, smoking, and high risk alcohol drinking. Associations were examined using multiple regression models, adjusted for gender, childhood socioeconomic, health, and cognitive measures. Results Private school and higher status university attendance were associated with favourable self-rated health, lower BMI, and beneficially associated with health related-behaviours. For example, private school attendance was associated with 0.56 (95% CI: 0.48, 0.65) odds of lower self-rated health (OR for higher status university: 0.32 (0.27, 0.37)). Associations were largely attenuated by adjustment for potential confounders, except for those of private schooling and higher status university attendance with lower BMI and television viewing, and less frequent take-away meal consumption. Conclusions Private school and higher status university attendance were related to better self-rated health, lower BMI, and multiple favourable health behaviours in midlife. Findings suggest that type or status of education may be an important under-researched construct to consider when documenting and understanding socioeconomic inequalities in health

The Evolution Of LMC X-4 Flares: Evidence For Super-Eddington Radiation Oozing Through Inhomogeneous Polar Cap Accretion Flows ?

We present the results of two extensive Rossi X-ray Timing Explorer observations of large X-ray flaring episodes from the high-mass X-ray binary pulsar LMC X-4. Light curves during the flaring episodes comprise bright peaks embedded in relatively fainter regions, with complex patterns of recurrence and clustering of flares. We identify precursors preceding the flaring activity. Pulse profiles during the flares appear to be simple sinusoids, and pulsed fractions are proportional to the flare intensities. We fit Gaussian functions to flare peaks to estimate the mean full-width-half-maximum to be $\sim$68 s. Significant rapid aperiodic variability exists up to a few hertz during the flares, which is related to the appearance of narrow, spiky peaks in the light curves. While spectral fits and softness ratios show overall spectral softening as the flare intensity increases, the narrow, spiky peaks do not follow this trend. The mean fluence of the flare peaks is (3.1 $\pm$ 2.9) $\times$ 10$^{40}$ ergs in the 2.5--25 keV energy range, with its maximum at $\sim$1.9 $\times$ 10$^{41}$ ergs. The flare peak luminosity reaches up to (2.1 $\pm$ 0.2) $\times$ 10$^{39}$ ergs s$^{-1}$, far above the Eddington luminosity of a neutron star. We discuss possible origins of the flares, and we also propose that inhomogeneous accretion columns onto the neutron star polar caps are responsible for the observed properties.Comment: 39 pages (including figures and tables), accepted for publication in Ap

Physical activity across age and study: a guide to data in six CLOSER studies

Explore the measures used to assess diverse aspects of physical activity within and across six CLOSER partner studie

Regional trends in birth weight in low- and middle-income countries 2013-2018

Background: Birth weight (BW) is a strong predictor of neonatal outcomes. The purpose of this study was to compare BWs between global regions (south Asia, sub-Saharan Africa, Central America) prospectively and to determine if trends exist in BW over time using the population-based maternal and newborn registry (MNHR) of the Global Network for Women\u27sand Children\u27s Health Research (Global Network).Methods: The MNHR is a prospective observational population-based registryof six research sites participating in the Global Network (2013-2018), within five low- and middle-income countries (Kenya, Zambia, India, Pakistan, and Guatemala) in threeglobal regions (sub-Saharan Af rica, south Asia, Central America). The birth weights were obtained for all infants born during the study period. This was done either by abstracting from the infants\u27 health facility records or from direct measurement by the registry staff for infants born at home. After controlling for demographic characteristics, mixed-effect regression models were utilized to examine regional differences in birth weights over time.Results: The overall BW meanswere higher for the African sites (Zambia and Kenya), 3186 g (SD 463 g) in 2013 and 3149 g (SD 449 g) in 2018, ascompared to Asian sites (Belagavi and Nagpur, India and Pakistan), 2717 g (SD450 g) in 2013 and 2713 g (SD 452 g) in 2018. The Central American site (Guatemala) had a mean BW intermediate between the African and south Asian sites, 2928 g (SD 452) in 2013, and 2874 g (SD 448) in 2018. The low birth weight (LBW) incidence was highest in the south Asian sites (India and Pakistan) and lowest in the African sites (Kenya and Zambia). The size of regional differences varied somewhat over time with slight decreases in the gap in birth weights between the African and Asian sites and slight increases in the gap between the African and Central American sites.Conclusions: Overall, BWmeans by global region did not change significantly over the 5-year study period. From 2013 to 2018, infants enrolled at the African sites demonstrated the highest BW means overall across the entire study period, particularly as compared to Asian sites. The incidence of LBW was highest in the Asian sites (India and Pakistan) compared to the African and Central American sites. Trial registration The study is registered at clinicaltrials.gov. ClinicalTrial.gov Trial Registration: NCT01073475

Development of the global network for women\u27s and children\u27s health research\u27s socioeconomic status index for use in the network\u27s sites in low and lower middle-income countries

Background: Socioeconomic status (SES) is an important determinant of health globally and an important explanatory variable to assess causality in epidemiological research. The 10th Sustainable Development Goal is to reduce disparities in SES that impact health outcomes globally. It is easier to study SES in high-income countries because household income is representative of the SES. However, it is well recognized that income is poorly reported in low- and middle- income countries (LMIC) and is an unreliable indicator of SES. Therefore, there is a need for a robust index that will help to discriminate the SES of rural households in a pooled dataset from LMIC.Methods: The study was nested in the population-based Maternal and Neonatal Health Registry of the Global Network for Women\u27s and Children\u27s Health Research which has 7 rural sites in 6 Asian, sub-Saharan African and Central American countries. Pregnant women enrolling in the Registry were asked questions about items such as housing conditions and household assets. The characteristics of the candidate items were evaluated using confirmatory factor analyses and item response theory analyses. Based on the results of these analyses, a final set of items were selected for the SES index.Results: Using data from 49,536 households of pregnant women, we reduced the data collected to a 10-item index. The 10 items were feasible to administer, covered the SES continuum and had good internal reliability and validity. We developed a sum score-based Item Response Theory scoring algorithm which is easy to compute and is highly correlated with scores based on response patterns (r = 0.97), suggesting minimal loss of information with the simplified approach. Scores varied significantly by site (p \u3c 0.001). African sites had lower mean SES scores than the Asian and Central American sites. The SES index demonstrated good internal consistency reliability (Cronbach\u27s alpha = 0.81). Higher SES scores were significantly associated with formal education, more education, having received antenatal care, and facility delivery (p \u3c 0.001).Conclusions: While measuring SES in LMIC is challenging, we have developed a Global Network Socioeconomic Status Index which may be useful for comparisons of SES within and between locations. Next steps include understanding how the index is associated with maternal, perinatal and neonatal mortality. Trial Registration NCT01073475 Socioeconomic status (SES) is an important determinant of health globally, and improving SES is important to reduce disparities in health outcomes. It is easier to study SES in high-income countries because it can be measured by income and what income is spent on, but this concept does not translate easily to low and middle income countries. We developed a questionnaire that includes 10 items to determine SES in low-resource settings that was added to an ongoing Maternal and Neonatal Health Registry that is funded by the National Institutes of Child Health and Human Development\u27s Global Network. The Registry includes sites that collect outcomes of pregnancies in women and their babies in rural areas in 6 countries in South Asia, sub-Saharan Africa and Central America. The Registry is population based and tracks women from early in pregnancy to day 42 post-partum. The questionnaire is easy to administer and has good reliability and validity. Next steps include understanding how the index is associated with maternal, fetal and neonatal mortality