Cohort profile: 'children of 1997': a Hong Kong Chinese birth cohort

Early-life exposure to ambient air pollutants and kidney function in adolescents: a cohort study based on the 'Children of 1997' Hong Kong birth cohort

OBJECTIVES

Air pollution is increasingly linked to impaired kidney function in adults. However, little is known about how early-life exposure to air pollutants affects kidney function in adolescents.

STUDY DESIGN

Cohort study.

METHODS

We leveraged data from the 'Children of 1997' Hong Kong population-representative birth cohort (N = 8327). Residential exposure to average ambient levels of four air pollutants, including inhalable particle (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and nitrogen monoxide (NO), during in utero, infancy, and childhood periods was estimated using the inverse distance weighting. Kidney function was assessed using estimated glomerular filtration rate (eGFR) calculated from age-adjusted equations for adolescents. Generalized linear regression was used to examine the association of air pollutant exposure in each period with kidney function at 17.6 years. Two-pollutant models tested the robustness of the association.

RESULTS

Of the 3350 participants included, 51.4% were boys. Exposure to PM10 was associated with poorer kidney function. Each interquartile range increment in PM10 was inversely associated with eGFR (β: -2.933, 95% confidence interval -4.677 to -1.189) in utero, -2.362 (-3.992 to -0.732) infancy, -2.708 (-4.370 to -1.047) childhood, and -2.828 (-4.409 to -1.247) overall. Exposure to PM10 and SO2in utero had a stronger inverse association with kidney function in males. The associations were robust to PM10 exposure in two-pollutant models.

CONCLUSIONS

Our findings suggest that early-life exposure to ambient PM10 and SO2 is associated with reduced kidney function in adolescents, especially exposure in utero.

Early-life exposure to ambient air pollution with cardiovascular risk factors in adolescents: Findings from the "Children of 1997" Hong Kong birth cohort

BACKGROUND

Long-term exposure to ambient air pollution is associated with cardiovascular disease (CVD) risk. Little is known about the impact of early-life exposure to air pollutants on CVD risk factors in late adolescence, which may track into adulthood. To clarify, we examined this question in a unique setting with high air pollution and a high level of economic development.

METHODS

This study leveraged the "Children of 1997" Hong Kong birth cohort (N = 8327), including here 3350 participants. We estimated ambient air pollutant exposure including inhalable particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and nitrogen monoxide (NO) by growth phase (in utero, infancy, childhood) and overall based on residential address. Generalized linear regression was used to assess the associations of air pollutants exposure by growth phase and sex with CVD risk factors (fasting blood glucose, glycosylated hemoglobin, lipid profile, blood pressure, and body mass index) at 17.6 years. We also assessed whether associations varied by sex.

RESULTS

Early life exposed had little association with glucose metabolism, blood pressure or body mass index, but after considering multiple comparisons early exposure to PM10 was associated with low density lipoprotein (LDL) in boys, with β and 95 % confidence intervals (95 % CI) of 0.184 (0.069 to 0.298) mmol/l, 0.151 (0.056 to 0.248) mmol/l, and 0.157 (0.063 to 0.252) mmol/l by per interquartile range (IQR) increment of PM10 for in utero, infancy, and overall, respectively. No such associations were evident for girls, differences by sex were evident.

CONCLUSIONS

Our study suggested sex-specific associations of early-life PM10 exposure with elevated LDL in adolescence, especially exposure in utero and infancy.

Prothrombin Complex Concentrate vs Conservative Management in ICH Associated With Direct Oral Anticoagulants

Importance

Intracerebral hemorrhage (ICH) associated with direct oral anticoagulant (DOAC) use carries extremely high morbidity and mortality. The clinical effectiveness of hemostatic therapy is unclear.

Objective

To compare the clinical and radiological outcomes of DOAC-associated ICH treated with prothrombin complex concentrate (PCC) vs conservative management.

Design, Setting, and Participants

In this population-based, propensity score-weighted retrospective cohort study, patients who developed DOAC-associated ICH from January 1, 2016, to December 31, 2021, in Hong Kong were identified. The outcomes of patients who received 25 to 50 IU/kg PCC with those who received no hemostatic agents were compared. Data were analyzed from May 1, 2022, to June 30, 2023.

Main Outcomes and Measures

The primary outcome was modified Rankin scale of 0 to 3 or returning to baseline functional status at 3 months. Secondary outcomes were mortality at 90 days, in-hospital mortality, and hematoma expansion. Weighted logistic regression was performed to evaluate the association of PCC with study outcomes. In unweighted logistic regression models, factors associated with good neurological outcome and hematoma expansion in DOAC-associated ICH were identified.

Results

A total of 232 patients with DOAC-associated ICH, with a mean (SD) age of 77.2 (9.3) years and 101 (44%) female patients, were included. Among these, 116 (50%) received conservative treatment and 102 (44%) received PCC. Overall, 74 patients (31%) patients had good neurological recovery and 92 (39%) died within 90 days. Median (IQR) baseline hematoma volume was 21.7 mL (3.6-66.1 mL). Compared with conservative management, PCC was not associated with improved neurological recovery (adjusted odds ratio [aOR], 0.62; 95% CI, 0.33-1.16; P = .14), mortality at 90 days (aOR, 1.03; 95% CI, 0.70-1.53; P = .88), in-hospital mortality (aOR, 1.11; 95% CI, 0.69-1.79; P = .66), or reduced hematoma expansion (aOR, 0.94; 95% CI, 0.38-2.31; P = .90). Higher baseline hematoma volume, lower Glasgow coma scale, and intraventricular hemorrhage were associated with lower odds of good neurological outcome but not hematoma expansion.

Conclusions and Relevance

In this cohort study, Chinese patients with DOAC-associated ICH had large baseline hematoma volumes and high rates of mortality and functional disability. PCC treatment was not associated with improved functional outcome, hematoma expansion, or mortality. Further studies on novel hemostatic agents as well as neurosurgical and adjunctive medical therapies are needed to identify the best management algorithm for DOAC-associated ICH.

Assessing the safety of lipid-modifying medications among Chinese adolescents: a drug-target Mendelian randomization study

BACKGROUND

With increasing hypercholesterolemia prevalence in East Asian adolescents, pharmacologic interventions (e.g., HMGCR inhibitors (statins) and PCSK9 inhibitors) may have to be considered although their longer-term safety in the general adolescent population is unclear. This study aims to investigate the longer-term safety of HMGCR inhibitors and PCSK9 inhibitors among East Asian adolescents using genetics.

METHODS

A drug-target Mendelian randomization study leveraging the Global Lipid Genetics Consortium (East Asian, n = 146,492) and individual-level data from Chinese participants in the Biobank clinical follow-up of Hong Kong's "Children of 1997" birth cohort (n = 3443, aged ~ 17.6 years). Safety outcomes (n = 100) included anthropometric and hematological traits, renal, liver, lung function, and other nuclear magnetic resonance metabolomics. Positive control outcomes were cholesterol markers from the "Children of 1997" birth cohort and coronary artery disease from Biobank Japan.

RESULTS

Genetic inhibition of HMGCR and PCSK9 were associated with reduction in cholesterol-related NMR metabolomics, e.g., apolipoprotein B (HMGCR: beta [95% CI], - 1.06 [- 1.52 to - 0.60]; PCSK9: - 0.93 [- 1.56 to - 0.31]) and had the expected effect on the positive control outcomes. After correcting for multiple comparisons (p-value < 0.006), genetic inhibition of HMGCR was associated with lower linoleic acid - 0.79 [- 1.25 to - 0.35]. Genetic inhibition of PCSK9 was not associated with the safety outcomes assessed.

CONCLUSIONS

Statins and PCSK9 inhibitors in East Asian adolescents appeared to be safe based on the outcomes concerned. Larger studies were warranted to verify these findings. This study serves as a proof of principle study to inform the medication safety among adolescents via genetics.

Breastfeeding and ApoB in late adolescence: a Hong Kong birth cohort study

Breastfeeding is widely promoted. Experimental evidence concerning long-term benefits is limited. Observational studies are open to bias from confounding by socio-economic position. We assessed the association of breastfeeding with late adolescent lipid sub-fractions, particularly apolipoprotein B (ApoB) and non-high-density lipoprotein cholesterol (non-HDL-c), overall and by sex. We took advantage of a setting where breastfeeding has little association with higher socio-economic position and where several results from randomized controlled trials of breastfeeding promotion have been replicated. We used the population-representative "Children of 1997" birth cohort comprising 88% of births in Hong Kong in April and May 1997. Associations of breastfeeding in the first 3 months of life (never, mixed, exclusive) with lipid sub-fractions were obtained using linear regression adjusted for potential confounders including parental socio-economic position, maternal place of birth, type of delivery, gestational age, and birth weight. Differences by sex were assessed. Multiple imputation and inverse probability weighting were used to recover the original sample. Of the 3462 participants included, mean age was 17.6 years and 48.8% were girls. Mean ApoB was 0.74 g/L (standard deviation 0.15). Exclusive versus never breastfeeding was associated with lower ApoB (-0.027 g/L, 95% confidence interval (CI)-0.046 to-0.007, p = 0.007) and lower non-HDL-c (-0.143 mmol/L, 95% CI-0.237 to-0.048) with similar estimates by sex.

CONCLUSION

Breastfeeding may provide some population-level lifelong protection against cardiovascular disease. This study supports policies promoting breastfeeding as a modifiable exposure that contributes to a healthy start in life as an investment for lifelong cardiovascular disease prevention.

WHAT IS KNOWN

• Apolipoprotein B (ApoB) is a recognized risk factor for cardiovascular disease, but whether breastfeeding affects ApoB in later life overall and by sex is unknown.

WHAT IS NEW

• Exclusive breastfeeding in the first 3 months of life was associated with lower ApoB in late adolescence, with similar estimates for both sexes. • The inverse association of breastfeeding with ApoB suggests that breastfeeding could reduce cardiovascular disease and overall mortality over the lifespan.

Investigating the impact of oral health on pregnancy and offspring outcomes: protocol for the Lifetime Impact of ORal heAlth (LIORA) cohort study

INTRODUCTION

Oral health is a fundamental component of well-being, and is closely associated with overall health and quality of life. Oral health may also affect the next generation. The children of mothers with poor oral health are likely to also have poor oral health as they go through life. We aim to investigate associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health.

METHODS AND ANALYSIS

The Lifetime Impact of Oral Health study is a prospective, observational cohort study being done at a single centre in Chongqing, China. A total of 1000 pregnant women will be recruited in their first trimester (11-14 weeks gestation). After obtaining informed consent, general and oral health assessments will be undertaken. Maternal lifestyle, demographic data and biospecimens (blood, hair, urine, nail clippings, saliva, dental plaque, buccal, vaginal and anal swabs) will be collected. Pregnancy outcomes will be recorded at the time of delivery. Cord blood and placenta samples will be collected. The offspring will be followed up for general and oral health examinations, neurodevelopmental assessments and biospecimen (dental plaque, saliva, buccal swabs, exfoliated primary dentition, urine, hair, nail clippings) collection until they are 15 years old. Biological samples will undergo comprehensive metabolomic, microbiome and epigenome analyses. Associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health will be investigated and the underlying mechanisms explored.

ETHICS AND DISSEMINATION

This project has been approved by the Research Ethics Committee of the Affiliated Hospital of Stomatology of Chongqing Medical University (CQHS-REC-2021 LSNo.23). Participants will be required to provide informed consent to participate in the study. Dissemination of findings will take the form of publications in peer-reviewed journals and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2100046898.

Association of growth patterns during infancy and puberty with lung function, wheezing and asthma in adolescents aged 17.5 years: evidence from ‘Children of 1997’ Hong Kong Chinese Birth Cohort

Background

Rapid growth is related to adverse respiratory outcomes although possibly confounded or limited by growth modelling methods. We investigated the association of infant and pubertal growth with lung function, wheezing and asthma in a non-Western setting.

Methods

In Hong Kong’s ‘Children of 1997’ Chinese birth cohort (n = 8327), weight during infancy and weight, height and body mass index (BMI) during puberty were modelled using a super-imposition by translation and rotation model to identify (larger or smaller) size, (earlier or later) tempo and (slower or faster) velocity. Sex-specific associations with forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC (Global Lung function Initiative z-score) and self-reported wheezing and asthma at ∼17.5 years were assessed.

Results

For each fraction higher than average weight growth velocity during infancy, FVC was higher in boys (0.90 SD, 95% CI 0.35; 1.44) and girls (0.77 SD, 95% CI 0.24; 1.30), FEV1/FVC was lower (–0.74 SD, 95% CI –1.38; –0.10) and wheezing was higher (odds ratio 6.92, 95% CI 1.60; 29.99) in boys and an inverse association with FVC was observed for tempo but not for size. Associations for weight growth velocity in puberty were similar but weaker. Greater size and higher velocity of BMI growth was associated with higher FVC, lower FEV1/FVC and higher asthma and wheezing risk.

Conclusion

Accelerated infant and pubertal weight growth were associated with disproportionate lung size and airway growth, and higher risk of asthma; optimizing early-life growth patterns could be important.

Birth cohort studies using symptom diaries for assessing respiratory diseases–a scoping review

Background

Respiratory infections are the most frequent health problem in childhood leading to morbidity and socioeconomic burden. Studying symptoms of respiratory infections in home based settings requires dedicated prospective cohort studies using diaries. However, no information is available on which birth cohort studies using symptom diary data. A review of birth cohort studies with available symptom diary data, follow-up data, and bio samples is needed to support research collaborations and create potential synergies.

Methods

We conducted a scoping review of birth cohort studies using diaries for the collection of respiratory symptoms. The scoping review was conducted in accordance with the PRISMA Extension. We searched the electronic databases PubMed, Embase, Web of science and CINAHL (last search November 2020) resulting in 5872 records (based on title and abstract screening) eligible for further screening.

Results

We examined 735 records as full text articles and finally included 57 according to predefined inclusion criteria. We identified 22 birth cohort studies that collect(ed) data on respiratory symptoms using a symptom diary starting at birth. Numbers of participants ranged from 129 to 8677. Eight studies collected symptom diary information only for the first year of life, nine for the first two years or less and six between three and six years. Most of the cohorts collected biosamples (n = 18) and information on environmental exposures (n = 19).

Conclusion

Information on respiratory symptoms with daily resolution was collected in several birth cohorts, often including related biosamples, and these data and samples can be used to study full spectrum of infections, particularly including those which did not require medical treatment.

Symptom Burden and Factors Associated with Acute Respiratory Infections in the First Two Years of Life-Results from the LoewenKIDS Cohort

Acute respiratory infections (ARIs) are the most common childhood illnesses worldwide whereby the reported frequency varies widely, often depending on type of assessment. Symptom diaries are a powerful tool to counteract possible under-reporting, particularly of milder infections, and thus offer the possibility to assess the full burden of ARIs. The following analyses are based on symptom diaries from participants of the German birth cohort study LoewenKIDS. Primary analyses included frequencies of ARIs and specific symptoms. Factors, which might be associated with an increased number of ARIs, were identified using the Poisson regression. A subsample of two hundred eighty-eight participants were included. On average, 13.7 ARIs (SD: 5.2 median: 14.0 IQR: 10-17) were reported in the first two years of life with an average duration of 11 days per episode (SD: 5.8, median: 9.7, IQR: 7-14). The median age for the first ARI episode was 91 days (IQR: 57-128, mean: 107, SD: 84.5). Childcare attendance and having siblings were associated with an increased frequency of ARIs, while exclusive breastfeeding for the first three months was associated with less ARIs, compared to exclusive breastfeeding for a longer period. This study provides detailed insight into the symptom burden of ARIs in German infants.

Linking cohort-based data with electronic health records: a proof-of-concept methodological study in Hong Kong

OBJECTIVES

Data linkage of cohort-based data and electronic health records (EHRs) has been practised in many countries, but in Hong Kong there is still a lack of such research. To expand the use of multisource data, we aimed to identify a feasible way of linking two cohorts with EHRs in Hong Kong.

METHODS

Participants in the 'Children of 1997' birth cohort and the Chinese Early Development Instrument (CEDI) cohort were separated into several batches. The Hong Kong Identity Card Numbers (HKIDs) of each batch were then uploaded to the Hong Kong Clinical Data Analysis and Reporting System (CDARS) to retrieve EHRs. Within the same batch, each participant has a unique combination of date of birth and sex which can then be used for exact matching, as no HKID will be returned from CDARS. Raw data collected for the two cohorts were checked for the mismatched cases. After the matching, we conducted a simple descriptive analysis of attention deficit hyperactivity disorder (ADHD) information collected in the CEDI cohort via the Strengths and Weaknesses of ADHD Symptoms and Normal Behaviour Scale (SWAN) and EHRs.

RESULTS

In total, 3473 and 910 HKIDs in the birth cohort and CEDI cohort were separated into 44 and 5 batches, respectively, and then submitted to the CDARS, with 100% and 97% being valid HKIDs respectively. The match rates were confirmed to be 100% and 99.75% after checking the cohort data. From our illustration using the ADHD information in the CEDI cohort, 36 (4.47%) individuals had ADHD-Combined score over the clinical cut-off in the SWAN survey, and 68 (8.31%) individuals had ADHD records in EHRs.

CONCLUSIONS

Using date of birth and sex as identifiable variables, we were able to link the cohort data and EHRs with high match rates. This method will assist in the generation of databases for future multidisciplinary research using both cohort data and EHRs.

The Role of Fetal, Infant, and Childhood Nutrition in the Timing of Sexual Maturation

Puberty is a crucial developmental stage in the life span, necessary to achieve reproductive and somatic maturity. Timing of puberty is modulated by and responds to central neurotransmitters, hormones, and environmental factors leading to hypothalamic-pituitary-gonadal axis maturation. The connection between hormones and nutrition during critical periods of growth, like fetal life or infancy, is fundamental for metabolic adaptation response and pubertal development control and prediction. Since birth weight is an important indicator of growth estimation during fetal life, restricted prenatal growth, such as intrauterine growth restriction (IUGR) and small for gestational age (SGA), may impact endocrine system, affecting pubertal development. Successively, lactation along with early life optimal nutrition during infancy and childhood may be important in order to set up timing of sexual maturation and provide successful reproduction at a later time. Sexual maturation and healthy growth are also influenced by nutrition requirements and diet composition. Early nutritional surveillance and monitoring of pubertal development is recommended in all children, particularly in those at risk, such as the ones born SGA and/or IUGR, as well as in the case of sudden weight gain during infancy. Adequate macro and micronutrient intake is essential for healthy growth and sexual maturity.

Nutrition in Pregnancy and Growth in Southwest China (NPGSC) cohort: Design, implementation, and characteristics

BACKGROUND

Pregnancy and birth cohorts addressing maternal nutrition and its impact on health outcomes have been rare in China, especially in Southwest China.

OBJECTIVES

To describe the design, implementation, baseline characteristics, and initial results of the Nutrition in Pregnancy and Growth in Southwest China (NPGSC) cohort.

POPULATION

Pregnant women with their children in Southwest China.

DESIGN

NPGSC participants have been prospectively recruited since 2014. Pregnant women were invited to participate in the study at their first routine ultrasound examination in gestational weeks 9-11. Data were assessed three times during pregnancy (9-11, 20-22, and 33-35 gestation weeks), and eight times in infants and toddlers.

METHODS

Pre-pregnancy body weight and height were self-reported; gestational weight gain was measured at regular intervals. Both food frequency questionnaires (FFQ) and 24-hour dietary recalls were used to collect dietary intakes during pregnancy, and FFQ for diet before pregnancy. Information on pregnancy outcomes was extracted from the medical birth registry. Anthropometry of children in the first 3 years of life was measured by trained investigators. Other child outcomes, including feeding practices (self-reported by mothers) and cognitive development (assessed by the Chinese version of Ages and Stages Questionnaire), were recorded.

PRELIMINARY RESULTS

Between 2014 and 2018, 12 989 pregnant women were enrolled, and 2296 children completed the 3 years follow-up. Among them, 115 pregnancies ended in stillbirth. Mean maternal pre-pregnancy BMI was 21.1 kg/m² and mean gestational weight gain was 13.5 kg 18.6% of mothers developed gestational diabetes and 1.5% of mothers were diagnosed with preeclampsia. Mean birthweight and birth length of children were, respectively, 3329 g and 49.4 cm.

CONCLUSION

We built a prospective cohort in Southwest China, which can provide valuable data to investigate the relevance of nutrition for the health of mothers and children.

Associations of growth from birth to puberty with blood pressure and lipid profile at ~17.5 years: evidence from Hong Kong's "Children of 1997" birth cohort

The role of early growth in later health is controversial. We examined the associations of growth at different phases from birth to puberty with blood pressure and lipid profile at ~17.5 years. In the population-representative "Children of 1997" birth cohort, growth was measured as (i) weight-for-age z score (WAZ) at birth and WAZ gains from 0 to 2 and 2 to 8 years and (ii) body-mass-index-for-age z score (BAZ) and length/height-for-age z score (LAZ) at 3 months and BAZ and LAZ gains from 3 months to 3 years, 3 to 8 years and 8 to 14 years, based on the World Health Organization growth standards/references. Adjusted partial least squares regression was used to assess simultaneously the associations of growth with height-, age- and sex-specific systolic (SBPZ) and diastolic blood pressure z scores (DBPZ), low- (LDL) and high-density lipoprotein (HDL) and triglycerides (TG) at ~17.5 years. Among 3410 children, higher WAZ, BAZ and LAZ gains from initial size to 8 years were associated with higher SBPZ. Higher gains in WAZ and BAZ from 2 to 8 years were consistently associated with higher DBPZ, LDL and TG and lower HDL. Lower LAZ at 3 months and higher LAZ gain from 3 months to 3 years were associated with lower HDL and higher TG. Greater growth in weight, body mass index and length/height had negative associations with blood pressure and lipid profile at ~17.5 years, but the differences by growth measure, phase and outcome suggest a complex underlying process.

Oral Health Birth Cohort Studies: Achievements, Challenges, and Potential

Birth cohorts are those among observational studies that provide understanding of the natural history and causality of diseases since early in life. Discussions during an International Association for Dental Research symposium in London, United Kingdom, in 2018, followed by a workshop in Bangkok, Thailand, in 2019, concluded that there are few birth cohort studies that consider oral health and that a broader discussion on similarities and differences among those studies would be valuable. This article aims to 1) bring together available long-term data of oral health birth cohort studies from the low, middle, and high-income countries worldwide and 2) describe similarities and differences among these studies. This work comprises 15 studies from all 5 continents. The most studied dental conditions and exposures are identified; findings are summarized; and methodological differences and similarities among studies are presented. Methodological strengths and weaknesses are also highlighted. Findings are summarized in 1) the negative impact of detrimental socioeconomic status on oral health changes over time, 2) the role of unfavorable patterns of dental visiting on oral health, 3) associations between general and oral health, 4) nutritional and dietary effects on oral health, and 5) intergenerational influences on oral health. Dental caries and dental visiting patterns have been recorded in all studies. Sources of fluoride exposure have been documented in most of the more recent studies. Despite some methodological differences in the way that the exposures and outcomes were measured, some findings are consistent. Predictive models have been used with caries risk tools, periodontitis occurrence, and permanent dentition orthodontic treatment need. The next steps of the group's work are as follows: 1) establishing a consortium of oral health birth cohort studies, 2) conducting a scoping review, 3) exploring opportunities for pooled data analyses to answer pressing research questions, and 4) promoting and enabling the development of the next generation of oral health researchers.

The effect of sleep duration on hemoglobin and hematocrit: observational and Mendelian randomization study

STUDY OBJECTIVE

Observationally sleep duration is positively associated with hemoglobin (Hgb), whether this association is causal and consistent by sex remains unclear. Here, we assessed the association of sleep duration with Hgb and hematocrit (Hct) observationally in late adolescence in a population-representative Chinese birth cohort "Children of 1997" with validation using Mendelian randomization (MR) in adults.

METHODS

In the "Children of 1997" birth cohort (recruited = 8327, included = 3144), we used multivariable linear regression to assess the adjusted associations of sleep duration (measured as time in bed) with Hgb and Hct at 17.5 years and any sex differences. Using two-sample MR, we assessed the effect of sleep duration on Hgb and Hct, based on 61 single nucleotide polymorphisms (SNPs) applied to genome-wide association studies of Hgb and Hct in adults (n = 361 194).

RESULTS

Observationally, self-reported sleep duration was positively associated with Hct (0.034 standard deviations [SDs] per hour, 95% confidence interval [CI] 0.019 to 0.049), but not with Hgb. Using MR longer sleep increased Hct (0.077 SD per hour, 95% CI 0.035 to 0.119) and Hgb (0.065 SD per hour, 95% CI 0.020 to 0.109) using Mendelian randomization pleiotropy residual sum and outlier (MR PRESSO), with more pronounced associations in men.

CONCLUSIONS

Our novel findings indicate sleep increases both Hgb and Hct, particularly in men, perhaps contributing to its restorative qualities. Potential difference by sex and the implications of these findings warrant investigation.

Influence of pubertal development on urinary oxidative stress biomarkers in adolescent girls in the New York LEGACY cohort

Puberty is a time of intense growth and differentiation of breast tissue and a window of susceptibility (WOS) for breast cancer. Although oxidative stress markers have been associated with breast cancer risk, it is unclear whether oxidative stress levels are different during the pubertal WOS, and if so, whether these differences are related to breast cancer susceptibility. We measured urinary biomarkers of whole body oxidative stress (urinary F2-Isoprostanes and 8-oxodeoxyguanosine (8-oxodG)) in 158 girls (ages 6-13 years), 71 with and 87 without a breast cancer family history (BCFH) from a cohort of adolescent girls from the New York site of the LEGACY cohort (Lessons in Epidemiology and Genetics in Adults Cancer from Youth). We compared levels of urinary oxidative stress biomarkers (F2-Isoprostanes and 8-oxodG) across the pubertal window, defined by Tanner Stage (TS) of breast development, both cross-sectionally and longitudinally within girls over an 18-month follow up period. Urinary oxidative stress biomarkers were unrelated to pubertal stages in cross-sectional analyses after considering adjustments for body mass index (BMI) and BCFH. In our longitudinal analysis, we found that urinary 8-oxodG levels, but not F2-Isoprostane levels, increased with age in BCFH + girls (β = 6.12, 95% CI = 0.08-12.16) compared to BCFH-girls. Higher BMI was associated with higher level of F2-Isoprostane in both cross-sectional (β = 0.02, 95% CI = 0.0004-0.05) and longitudinal analysis (β = 0.02, 95% CI = 0.0002-0.05). These findings support that higher BMI increases oxidative stress biomarkers over the pubertal window and that there are changes in 8-oxodG oxidative stress biomarkers in girls with a BCFH compared to girls without a BCFH.

Association of Sugar-Sweetened Beverage Frequency with Adiposity: Evidence from the "Children of 1997" Birth Cohort

Background: Observationally, sugar-sweetened beverage (SSB) consumption is associated with adiposity in Western children but could be confounded. We examined the association of SSB frequency with adiposity in the non-Western setting of Hong Kong. Methods: We examined the associations of SSB consumption frequency at 11 and 13 years assessed by using a food frequency questionnaire with subsequent body mass index (BMI) z-score and overweight/obesity up to 18 years using generalized estimating equations, and with waist circumference, waist-to-hip ratio, and body fat percentage at 16–19 years using linear regression in a population-representative Chinese birth cohort “Children of 1997” (n = 3628). Results: At 11 and 13 years, 6.8% and 8.2% of children respectively consumed SSB daily. Neither SSB frequency at 11 nor at 13 years was associated with subsequent BMI z-score or overweight/obesity up to 18 years, or with waist circumference, waist-to-hip ratio, or body fat percentage at 16–19 years adjusted for age, sex, socioeconomic position, health status, physical activity and other food consumption, although bias to the null from under-reporting cannot be eliminated. Conclusion: Although we cannot definitively exclude a small association of SSB frequency with adiposity, lack of association of SSB frequency with adiposity in a non-Western setting with low SSB consumption suggests that the role of SSB in adiposity appears to be minor.

Population neuroscience: challenges and opportunities for psychiatric research in low- and middle-income countries

Objective:

Population neuroscience is an emerging field that combines epidemiology and neuroscience to study how genes and the environment shape typical and atypical brain functioning. The objective of this study was to review key studies on population neuroscience from low- and middle-income countries (LMICs) and to identify potential gaps vis-à-vis studies conducted in high-income countries.

Methods:

We conducted a systematic review to search for longitudinal cohort studies investigating the development of psychiatric disorders in children and adolescents in LMICs. We performed an electronic search in the EMBASE and MEDLINE databases from inception to July 5th, 2019.

Results:

We found six cohorts from four countries that met our search criteria: three cohorts from Brazil, one from China, one from South Africa, and one from Mauritius. Relevant examples of findings from these studies are reported.

Conclusion:

Our results demonstrate the impact of the valuable science output these cohort designs promote, allowing LMICs to have a share in frontline global psychiatry research. National and international funding agencies should invest in LMIC population neuroscience in order to promote replication and generalization of research from high-income countries.

A cohort study of factors that influence oral health-related quality of life from age 12 to 18 in Hong Kong

Background

There is a lack of cohort studies on the influence factors of oral health-related quality of life (OHRQoL). This study aimed to follow subjects from age 12 to 18 to analyse the sociodemographic and clinical factors that may influence OHRQoL.

Methods

This cohort study selected a representative sample from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. Child Perceptions Questionnaires (CPQ_11–14) with 8 items (CPQ_11–14-ISF: 8) and 37 items were used to assess OHRQoL at age 12 and age 15, respectively; Oral Health Impact Profile (OHIP-14) was used to assess OHRQoL at age 18. Wilcoxon signed ranks test and Friedman’s test were used to analyse the age-related change of OHRQoL and malocclusion from age 12 to 18. Generalized estimating equations were used to analyse the influence factors of OHRQoL and to calculate adjusted risk ratio (RR).

Results

Subjects recruited in this study were 589 (305 females, 284 males), 364 (186 females, 178 males) and 300 (165 females, 135 males) at age 12, 15 and 18, respectively. Among them, 331 subjects (172 females, 159 males) were followed from age 12 to 15, and 118 subjects (106 females, 82 males) were followed from age 12 to 18. Subjects had less severe malocclusion at age 12 than at ages 15 and 18 (p = 0.000, measured by Dental Aesthetic Index). Age, periodontal status, and malocclusion had an effect on OHRQoL. When compared with OHRQoL at age 12, worse OHRQoL was observed at age 15 (adjusted RR = 1.06, 95%CI = 1.01–1.12, p = 0.032), but not at age 18 (adjusted RR = 1.01, 95%CI = 0.95–1.08, p = 0.759). Unhealthy periodontal conditions had a negative effect on OHRQoL (adjusted RR = 1.14, 95%CI = 1.04–1.25, p = 0.007). Only severe malocclusions had a negative effect on OHRQoL; a more severe malocclusion was associated with a higher effect on OHRQoL (adjusted RR = 1.09, 95%CI = 1.01–1.18, p = 0.032 for severe malocclusion, and adjusted RR = 1.17, 95%CI = 1.07–1.28, p = 0.001 for very severe malocclusion measured by Dental Aesthetic Index).

Conclusion

Age, periodontal status, and malocclusion had an influence on OHRQoL from age 12 to 18. When clinicians attempt to improve subjects’ OHRQoL, it is necessary to consider these factors.

Age of puberty and Sleep duration: Observational and Mendelian randomization study

Earlier age of puberty has detrimental consequences for many aspects of health. Here, for the first time, we assessed the association of earlier puberty with sleep duration observationally and with validation using Mendelian Randomization. In the “Children of 1997” birth cohort (n = 8,327), we used adjusted multivariable logistic regression to assess the associations of each clinically assessed marker of earlier puberty with self-report sleep duration in adolescence. Using two-sample MR, we assessed the effect of earlier puberty timing based on 203 single nucleotide polymorphisms applied to genome wide association studies of sleep duration in adults (n = 335,410). In “Children of 1997”, cross-sectionally, older age of menarche was associated with longer (9+ hours) sleep duration [odds ratio (OR) 1.11, 95% confidence interval (CI) 1.01 to 1.21] at 13.5 years. The other earlier puberty markers were unrelated to sleep duration. Using inverse variance weighting, later of age at menarche increased adult sleep duration [0.020 per category, 95% CI 0.006 to 0.034]. This study demonstrated a causal effect of age at menarche on adult sleep duration, since age of menarche also affects obesity, our novel finding may be relevant to the observed relation of sleep duration with obesity and poor health.

The effect of liver enzymes on body composition: A Mendelian randomization study

Background

Higher alanine transaminase (ALT), indicating poor liver function, is positively associated with diabetes but inversely associated with body mass index (BMI) in Mendelian randomization (MR) studies, suggesting liver function affects muscle mass. To clarify, we assessed the associations of liver enzymes with muscle and fat mass observationally with two-sample MR as a validation.

Methods

In the population-representative “Children of 1997” birth cohort (n = 3,455), we used multivariable linear regression to assess the adjusted associations of ALT and alkaline phosphatase (ALP) at ~17.5 years with muscle mass and body fat percentage observationally. Genetic variants predicting ALT, ALP and gamma glutamyltransferase (GGT) were applied to fat-free and fat mass in the UK Biobank (n = ~331,000) to obtain unconfounded MR estimates.

Results

Observationally, ALT was positively associated with muscle mass (0.11 kg per IU/L, 95% confidence interval (CI) 0.10 to 0.12) and fat percentage (0.15% per IU/L, 95% CI 0.13 to 0.17). ALP was inversely associated with muscle mass (-0.03 kg per IU/L, 95% CI -0.04 to -0.02) and fat percentage (-0.02% per IU/L, 95% CI -0.03 to -0.01). Using MR, ALT was inversely associated with fat-free mass (-0.41 kg per 100% in concentration, 95% CI -0.64 to -0.19) and fat mass (-0.58 kg per 100% in concentration, 95% CI -0.85 to -0.30). ALP and GGT were unclearly associated with fat-free mass or fat mass.

Conclusion

ALT reducing fat-free mass provides a possible pathway for the positive association of ALT with diabetes and suggests a potential target of intervention.

Birth weight and prematurity with lung function at ~17.5 years: "Children of 1997" birth cohort

We aimed to determine if prematurity and lower birth weight are associated with poorer lung function in a non-western developed setting with less marked confounding by socioeconomic position. Using multivariable linear regression in Hong Kong’s “Children of 1997” birth cohort, adjusted associations of prematurity and birth weight with forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and forced expiratory flow at 25–75% of the pulmonary volume (FEF_25–75%) at ~17.5 years were assessed. Associations for birth weight were stronger in boys for FEV₁ (boys: 0.31 L, 95% confidence interval (CI) 0.24 to 0.38, girls: 0.18 L, 95% CI 0.12 to 0.25), FVC (boys: 0.36 L, 95% CI 0.27 to 0.44, girls: 0.22 L, 95% CI 0.15 to 0.28) and FEF_25–75% (boys: 0.35 L, 95% CI 0.21 to 0.49, girls: 0.22 L, 95% CI 0.09 to 0.34) adjusted for age, socioeconomic position and infant and maternal characteristics. Similarly adjusted, preterm birth (compared to full-term birth) was associated with lower FEV₁/FVC and FEF_25–75%. Thus, associations of lower birth weight, especially in boys, and prematurity with poorer lung function at 17.5 years were found. Identifying underlying mechanism might contribute to the improvement of pulmonary health and the prevention of adult respiratory illness.

The effect of liver enzymes on adiposity: a Mendelian randomization study

Poorer liver function is positively associated with diabetes in Mendelian randomization (MR) studies. Observationally, adiposity is associated with poorer liver function. To clarify the etiology, we assessed the association of liver enzymes with adiposity observationally and using two-sample MR for validation. In the "Children of 1997" birth cohort, we used multivariable linear regression to assess the associations of alanine transaminase (ALT) and alkaline phosphatase (ALP) at ~17.5 years with body mass index (BMI) (n = 3,458). Using MR, genetic predictors of ALT, ALP and gamma glutamyltransferase (GGT), were applied to genome-wide association studies of BMI (n = 681,275), waist circumference (WC) (n = 224,459) and waist-hip ratio (WHR) (n = 224,459) to obtain unconfounded estimates. Observationally, ALT was positively associated with BMI (0.10 kg/m² per IU/L, 95% confidence interval (CI) 0.09 to 0.11). ALP was inversely associated with BMI (-0.018 kg/m² per IU/L, 95% CI -0.024 to -0.012). Using MR, ALT was inversely associated with BMI (-0.14 standard deviation per 100% change in concentration, 95% CI -0.20 to -0.07), but not WC or WHR. ALP and GGT were unrelated to adiposity. Poorer liver function might not cause adiposity; instead higher ALT might reduce BMI, raising the question as to the role of ALT in body composition.

Negative Affect Shared with Siblings is Associated with Structural Brain Network Efficiency and Loneliness in Adolescents

Loneliness has a strong neurobiological basis reflected by its specific relationships with structural brain connectivity. Critically, affect traits are highly related to loneliness, which shows close association with the onset and severity of major depressive disorder. This diffusion imaging study was conducted on a sample of adolescent siblings to examine whether positive and negative affect traits were related to loneliness, with brain network efficiency playing a mediating role. The findings of this study confirmed that both global and average local efficiency negatively mediated the association between low positive affect and high negative affect and loneliness, and the mediation was more sensitive to sibling-shared affect traits. The findings have important implications for interventions targeted at reducing the detrimental impact of familiar negative emotional experiences and loneliness.

The effect of birth weight on body composition: Evidence from a birth cohort and a Mendelian randomization study

BACKGROUND

Lower birth weight is associated with diabetes although the underlying mechanisms are unclear. Muscle mass could be a modifiable link and hence a target of intervention. We assessed the associations of birth weight with muscle and fat mass observationally in a population with little socio-economic patterning of birth weight and using Mendelian randomization (MR) for validation.

METHODS

In the population-representative "Children of 1997" birth cohort (n = 8,327), we used multivariable linear regression to assess the adjusted associations of birth weight (kg) with muscle mass (kg) and body fat (%) at ~17.5 years. Genetically predicted birth weight (effect size) was applied to summary genetic associations with fat-free mass and fat mass (kg) from the UK Biobank (n = ~331,000) to obtain unconfounded estimates using inverse-variance weighting.

RESULTS

Observationally, birth weight was positively associated with muscle mass (3.29 kg per kg birth weight, 95% confidence interval (CI) 2.83 to 3.75) and body fat (1.09% per kg birth weight, 95% CI 0.54 to 1.65). Stronger associations with muscle mass were observed in boys than in girls (p for interaction 0.004). Using MR, birth weight was positively associated with fat-free mass (0.77 kg per birth weight z-score, 95% CI 0.22 to 1.33) and fat mass (0.58, 95% CI 0.01 to 1.15). No difference by sex was evident.

CONCLUSION

Higher birth weight increasing muscle mass may be relevant to lower birth weight increasing the risk of diabetes and suggests post-natal muscle mass as a potential target of intervention.

Orthodontic Treatment Need and the Psychosocial Impact of Malocclusion in 12-Year-Old Hong Kong Children

Objectives

To determine the prevalence of orthodontic treatment need in 12-year-old children in Hong Kong and its relationship with the psychosocial impact of malocclusion and to assess their associations with sociodemographic factors.

Materials and Methods

A random sample of 687 12-year-old children was recruited from 45 secondary schools in Hong Kong. Orthodontic treatment need was assessed on study models by five indices: the Dental Health Component of the Index of Orthodontic Treatment Need (IOTN-DHC), the Aesthetic Component of the IOTN (IOTN-AC), the Dental Aesthetic Index (DAI), the Index of Complexity Outcome and Need (ICON), and the Peer Assessment Rating (PAR). The psychosocial impact of malocclusion on participants and sociodemographic factors were obtained from a questionnaire. Logistic regression was used to examine the correlations between treatment need and the psychosocial impact of malocclusion as well as their associations with sociodemographic factors.

Results

The final number of participants was 667 (339 boys and 328 girls, participation rate 667/687 = 97.1%). The prevalence of orthodontic treatment need varied depending on the indices used (10.9–47.8%), but significant correlations were found among the five indices (p < 0.01). The uptake of treatment among the cohort was 2.3%. Boys had higher IOTN-DHC (p < 0.05), DAI (p < 0.05), and PAR (p = 0.05) scores than girls. IOTN-AC was significantly associated with the psychosocial impact of malocclusion (p < 0.05). Parents' level of education and household income were not significantly associated with either treatment need or the psychosocial impact of malocclusion (p > 0.05).

Conclusion

The need for orthodontic treatment in 12-year-old children in Hong Kong remained high, and the uptake of treatment was low. Boys had a higher normative treatment need than girls. Among the five indices, IOTN-AC appears to be the best indicator of the psychosocial impact of malocclusion.

Sleep Duration and Adiposity in Children and Adults: Observational and Mendelian Randomization Studies

OBJECTIVE

This study used two complementary designs, an observational and a Mendelian randomization (MR) study, to assess whether sleep duration causes adiposity in children and adults.

METHODS

In Hong Kong's "Children of 1997" birth cohort, the adjusted cross-sectional associations of sleep duration with BMI z score and obesity and overweight were assessed at ~11 years of age. Generalized estimating equations were also used to examine longitudinal associations of sleep duration at ~11 years with annual BMI z score and obesity and overweight at about 11 to 16 years of age. Using MR, this study assessed the association of genetically predicted sleep duration, based on 54 single-nucleotide polymorphisms, applied to genetic studies of adiposity in children (n = 35,668), men (n = 152,893), and women (n = 171,977).

RESULTS

Longer sleep was cross-sectionally associated with lower BMI z score at ~11 years of age (-0.13 per category, 95% CI: -0.22 to -0.04) and at about 11 to 16 years of age longitudinally in girls (-0.39, 95% CI: -0.66 to -0.13). Using MR, sleep duration was inversely associated with BMI in children (-0.29 SD per hour, 95% CI: -0.54 to -0.04), but was not clearly associated with BMI in adults, particularly for women.

CONCLUSIONS

A small beneficial effect of sleep on BMI in children cannot be ruled out.

Associations of growth from birth to puberty with glycemic indicators at ~17.5 years: Evidence from Hong Kong's "Children of 1997" birth cohort

BACKGROUND

From an evolutionary biology perspective, where growth and reproduction trade-off against longevity, we assessed the associations of growth from birth to puberty by phase with later glycemic indicators and any differences by sex.

METHODS

In the population-representative Hong Kong Chinese "Children of 1997" birth cohort (n = 8327), the relation of initial size (weight-for-age z score (WAZ) at birth, length/height-for-age z score (LAZ) at 3 months or body-mass-index-for-age z score (BAZ) at 3 months based on the World Health Organization growth standards/references) and growth at different phases (WAZ gains from 0 to 2 and 2 to 8 years, LAZ or BAZ gains from 3 months to 3 years, 3 to 8 years and 8 to 14 years) with fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) at ~17.5 years, was assessed using adjusted partial least squares regression. Additional analyses further considered growth in late and early infancy.

RESULTS

This study included 3276 of the cohort participants. Higher WAZ gain from 2 to 8 years, LAZ and BAZ gains from 3 to 8 years were consistently associated with higher FPG, adjusted for maternal and infant characteristics, family history of diabetes and household income. Also, higher BAZ gain from 3 to 8 years was associated with higher HbA1c. These associations did not differ by sex.

CONCLUSIONS

Our findings suggest different mechanisms could underlie the pathogenesis of glucose intolerance. Factors that drive specific growth at different phases need to be evaluated to better inform child growth management for long-term health outcomes.

Breastfeeding in Infancy and Lipid Profile in Adolescence

OBJECTIVES

Breast milk has higher cholesterol than formula. Infants who are breastfed have different cholesterol synthesis and metabolism in infancy than infants who are formula fed. Little is known as to whether breastfeeding is associated with subsequent lipid profile, independent of adiposity. We assessed the association of breastfeeding in early infancy with lipid profile and adiposity at ∼17.5 years in a setting where exclusive breastfeeding is not associated with higher socioeconomic position.

METHODS

We used multivariable linear regression with multiple imputation and inverse probability weighting to examine the associations of contemporaneously reported feeding in the first 3 months of life (exclusive breastfeeding [7.5%], mixed feeding [40%], or always formula feeding [52%]) with lipids and adiposity at ∼17.5 years in 3261 participants in the Hong Kong Chinese birth cohort Children of 1997, adjusting for sex, birth weight, gestational weeks, parity, pregnancy characteristics, parents' highest education, mother's place of birth, and age at follow-up.

RESULTS

Exclusive breastfeeding, but not mixed feeding at 0 to 3 months, compared with formula feeding was associated with lower total cholesterol and low-density lipoprotein cholesterol but not with high-density lipoprotein cholesterol at ∼17.5 years. BMI and fat percentage measured by bioimpedance did not differ by type of infant feeding.

CONCLUSIONS

Exclusive breastfeeding in early infancy may promote a healthier lipid profile in late adolescence through mechanisms unrelated to adiposity, implicating its potential long-term benefits for cardiovascular health.

Association of infant growth with emergence of permanent dentition among 12 year-aged southern Chinese school children

Background

There is a need to comprehensively investigate the relationship between tooth eruption and infant growth to explain the theory of tooth emergence. This study aimed to investigate the association between infant growth during the first year of life and the emergence of the permanent teeth.

Methods

A random sample of 668, 12-year-old students was recruited from a birth cohort. Erupted permanent tooth number was recorded. The association of infant growth (growth trajectories and growth rates) and permanent tooth emergence was examined through logistic regression analyses. The regression model was adjusted by potential confounders including gender, gestational age, mode of delivery, type of feeding, parental education, and health status.

Results

The response rate was 76.9% (n = 514). Two hundred and forty-five (47.7%) children had all 28 permanent teeth erupted. Infants who had higher birth weight z-scores and those who had grown slowly during the first three months of life were more likely to have complete permanent teeth emergence at their 12-year-old in both unadjusted (p <  0.01) and adjusted model (adjusted for gender, gestational age, mode of delivery, type of feeding, parental education, and health status, p <  0.01). However, no significant association was found between the growth trajectories and permanent tooth emergence in either unadjusted or adjusted models (p > 0.05).

Conclusion

Birth weight and infant growth during the first three months of life might be associated with permanent tooth emergence at their 12 years of age. This association may be applied in the assessment of risk for dental caries or malocclusion.

Sleep duration and risk of diabetes: Observational and Mendelian randomization studies

Inadequate sleep could contribute to type 2 diabetes, but observational studies are inconsistent and open to biases, particularly from confounding. We used Mendelian randomization (MR) to obtain an unconfounded estimate of the effect of sleep duration on diabetes, fasting glucose (FG) and hemoglobin A1c (HbA1c), and an observation study to assess differences by sex. Using MR, we assessed the effects of genetically instrumented sleep on diabetes, based on 68 single nucleotide polymorphisms (SNPs), applied to the DIAbetes Genetics Replication and meta-analysis case (n = 26,676)-control (n = 132,532) study and on FG and HbA1c, based on 55 SNPs, applied to the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) study of FG (n = 122,743) and HbA1c (n = 123,665). In the population-representative Hong Kong Chinese "Children of 1997" birth cohort we assessed whether associations of sleep duration at ~17.5 years with FG and HbA1c differed by sex. Using inverse variance weighting with multiplicative random effects, sleep duration was not associated with diabetes (odds ratio (OR) 0.85 per hour of sleep, 95% confidence interval (CI) 0.64 to 1.13), FG (-0.032 mmol/l per hour of sleep, 95% CI -0.126 to 0.063) or HbA1c (-0.022% per hour of sleep, 95% CI -0.069 to 0.024). In "Children of 1997", the associations of sleep duration with FG differed by sex (p for interaction 0.05) but not with HbA1c. Overall sleep duration does not appear to be related to diabetes, FG or HbA1c, but the possibility of sex differences merits investigation.

Glucose-6-phosphate dehydrogenase deficiency and metabolic profiling in adolescence from the Chinese birth cohort: "Children of 1997"

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects 6.0% of the global population. G6PD deficiency has been associated with lower risk of cardiovascular disease and higher risk of diabetes, which could be etiologically informative, but these relations are uncertain. To clarify, we assessed the associations of G6PD deficiency with serum metabolite profiles in late adolescence.

METHODS

In a nested case-control study of 50 G6PD-deficient late adolescents (~17.5 years) and 150 sex-matched non-G6PD-deficient controls from a Chinese birth cohort: "Children of 1997", we compared 80 serum metabolites analyzed by nuclear magnetic resonance spectrometry using adjusted linear regression with Bonferroni correction for testing 12 traits (p < 0.0042).

RESULTS

G6PD-deficiency was inversely associated with serum levels of total cholesterol (-0.27 mmol, 95% confidence interval (CI) -0.46, -0.09, p = 0.004), free cholesterol (-0.08 mmol, 95% CI -0.13, -0.03, p = 0.003) and creatinine (-0.004 mmol, 95% CI -0.007, -0.001, p = 0.003), adjusted for sex and parental education. G6PD deficiency was not associated with fatty acids, amino acids, glucose or related metabolites, ketone bodies or glycoprotein.

CONCLUSIONS

G6PD deficiency is associated with lower serum levels of cholesterol and creatinine, but not other serum metabolites. Whether such differences are transient or become more evident in adulthood warrant further investigations.

The factors that influence oral health-related quality of life in young adults

Background

Young adulthood is a time when subjects transform their role from a dependent child to an independent social identity. This cross-sectional study aimed to analyze the sociodemographic and clinical factors that may influence the OHRQoL of 18-year-old young adults.

Methods

A representative sample was selected from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. The oral health impact profile (OHIP-14) was used to measure OHRQoL. Adjusted OR was calculated by ordinal logistic regression.

Results

A total of 300 eligible subjects (165 females, 135 males) were recruited. Females had more severe caries than males; however, gender was not a significant factor of OHRQoL. Household income affected OHRQoL more than parents’ education did: household income had effects on physical pain, psychological discomfort, psychological disability, and the total OHIP; while parents’ education had some effects on functional limitation, physical pain and psychological discomfort. As for clinical factors, unhealthy periodontal conditions were more prevalent than caries (94.67% vs. 59.00%); however, both of them showed no effect on OHRQoL. Malocclusion had a negative effect on OHRQoL; the most affected subscales were psychological discomfort and psychological disability.

Conclusion

In this study, family ecosocial factors and malocclusion had an effect on OHRQoL. Among the family ecosocial factors, it was household income that had the most effect on OHRQoL. Malocclusion mainly affected the subscales of psychological discomfort and psychological disability. Gender, periodontal status and caries had no effect on young adults’ OHRQoL.

Behavioral problem trajectories and self-esteem changes in relation with adolescent depressive symptoms: a longitudinal study

PURPOSE

Prospectively childhood behavioral problems and low self-esteem are associated with depression. However, these mental health changes over time have never been examined. This study assessed the association of childhood behavioral trajectories and self-esteem changes over time with adolescent depressive symptoms.

METHODS

Parent-reported Rutter behavioral assessments and self-reported Culture-Free Self-Esteem Inventories (SEI) were obtained via record linkage from the Student Health Service, Department of Health (Hong Kong), and the Patient Health Questionnaire-9 (PHQ-9) depressive symptom scores were obtained via active follow-up of the Hong Kong's Children of 1997" Chinese birth cohort. Partitional clustering was used to generate homogenous trajectories between ~ 7 and ~ 11 years for Rutter scores. Changes in low self-esteem between ~ 10 and ~ 12 years were obtained from the SEI. Multiple linear regression was used to estimate their associations with depressive symptom scores at ~ 13 years.

RESULTS

Four trajectories/groups (stable low, declining, rising, and stable high) of Rutter score and self-esteem groups were created. The stable low behavioral trajectory was associated with the fewest depressive symptoms while the stable high trajectory had 1.23 more depressive symptoms [95% confidence interval (CI) 0.84 to 1.61] than the stable low trajectory. Consistently low self-esteem (stable low) was associated with 2.96 more depressive symptoms (95% CI 2.35-3.57) compared to consistently high self-esteem (stable high).

CONCLUSIONS

Sustained or worsening childhood behavioral problems and low self-esteem were precursors of adolescent depressive symptoms, and as such could be an early indicator of the need for intervention.

Opposite associations of household income with adolescent body mass index according to migrant status: Hong Kong's "Children of 1997" birth cohort

BACKGROUND/OBJECTIVES

In economically developed settings, household income is usually inversely associated with child and adolescent adiposity, but this association may not extend to migrants. Hong Kong is a unique developed setting to study how household income and adolescent adiposity vary by migrant status given many Hong Kong-born Chinese children were born to parents who migrated from neighboring provinces of Mainland China.

SUBJECTS/METHODS

We examined differences between the associations of absolute household income vs. relative household income on adolescent body mass index (BMI) z-score or overweight (including obesity) status using a linear or logistic model in a Chinese birth cohort (n = 5613, 68% follow-up). We focused on whether the associations differed by mother's or father's migrant status (birthplace).

RESULTS

No association was found between absolute household income and BMI z-score among adolescents with either native or migrant mothers. However, the association of relative household income with BMI z-score varied by mother's migrant status (P-values for interaction <0.0005). In adolescents of native born mothers, greater relative household income deprivation was associated with higher BMI z-score (0.03 z-score per USD 128 difference in Yitzhaki index, 95% confidence interval (CI) 0.01 to 0.05). However, in adolescents of migrant mothers, greater relative household income deprivation was associated with lower BMI z-score (-0.05, 95% CI -0.09 to -0.01). Similar association of relative household income with overweight (including obesity) status was found in adolescents of native born mothers but not in adolescents of migrant mothers.

CONCLUSIONS

Relative income (mediated by social comparisons with others in society) appears to be relevant to adolescent adiposity, but the association depends on the interplay between individual characteristics (migrant background) and societal context.

Birth weight, gestational age and late adolescent liver function using twin status as instrumental variable in a Hong Kong Chinese birth cohort: "Children of 1997"

Birth weight (BW) is inversely associated with diabetes and liver function in Mendelian Randomization studies. Observationally, lower BW is usually also associated with poorer liver function. However, these studies could be confounded by socioeconomic position. Here we assessed if BW is associated with liver function in a unique population with little socio-economic patterning of BW, using both instrumental variable and an observational analysis. We used instrumental variable analysis (IVA) to assess the association of BW with liver function (alanine transaminase (ALT), alkaline phosphatase (ALP), bilirubin, and albumin) at ~17 years with twin status as an instrumental variable in the prospective population-representative "Children of 1997" birth cohort (n = 8327). We also conducted an observational analysis adjusted for sex, maternal age, maternal migrant status, smoking and parental socio-economic position. A generalized linear model with gamma family was used for ALT, ALP, and bilirubin because they are not normally distributed. Using IVA, BW was not associated with ALT, ALP or bilirubin, but was possibly negatively associated with albumin (-1.12 g/L, 95% confidence interval (CI) -2.08 to -0.16). Observationally, BW was negatively associated with ALT (-1.23 IU/L, 95% CI -2.16 to -0.30), ALP (-1.72 IU/L, 95% CI -3.43 to -0.01) and higher albumin (-0.23 g/L, 95% CI -0.40 to -0.06). Poor liver function may be a pathway by which the risks of lower BW are actuated. This insight might help identify post-natal targets of intervention to mitigate the adverse health effects of lower birth weight.

In utero exposure to gestational diabetes and adiposity: does breastfeeding make a difference?

BACKGROUND/OBJECTIVES

Short-term breastfeeding from mothers with gestational diabetes (GDM) may programme metabolism and increase offspring diabetes risk. We examined the association of in utero GDM exposure with adiposity from infancy to adolescence, and whether any association was modified by breastfeeding during early infancy.

METHODS

In the prospective Chinese birth cohort "Children of 1997" (n = 7342, 88% follow-up rate), generalised estimate equations with multiple imputation were used to assess associations of in utero GDM exposure with age- and sex-specific body mass index (BMI) z-score during infancy (3 and 9 months), childhood (2- < 8 years) and adolescence (8-16 years), adjusted for sex, parity, maternal age, birth place, preeclampisa, smoking, and family socio-economic position. We also tested whether the associations differed by mode of infant feeding (always formula-fed, mixed, always breastfed) during the first three months of life.

RESULTS

In utero GDM exposure (7.5%) was associated with a lower BMI z-score during infancy (-0.13, 95% confidence interval (CI) -0.22, -0.05) but higher BMI z-scores during childhood (0.14, 95% CI 0.03, 0.25) and adolescence (0.25 95% CI 0.11, 0.38). Breastfeeding for the first three months did not modify the association of in utero GDM status with subsequent BMI (all p values for interaction >0.4).

CONCLUSIONS

In utero GDM exposure was associated with greater adiposity during childhood and adolescence. Breastfeeding in early infancy from mothers with GDM was not associated with greater adiposity in children and thus should still be encouraged.

The Associations of Breast Feeding with Infant Growth and Body Mass Index to 16 years: 'Children of 1997'

BACKGROUND

Controversial findings concerning associations of breast feeding with growth have been reported. This study examined whether the associations of breast feeding with early growth trajectories and body mass index to 16 years differed by sex or age.

METHODS

In Hong Kong's 'Children of 1997' population-representative birth cohort, contemporaneously reported breast-feeding status in the first 3 months was classified as exclusive breast feeding (BF) (n = 470), mixed feeding (MF) (n = 2693), and formula feeding (FF) (n = 4204). Adjusted sex- and age-specific associations of breast feeding with infant growth (gains in weight-for-age z scores (WAZ), length/height-for-age z scores (LAZ), and body-mass-index-for-age z score (BAZ) based on the World Health Organization standards/references from birth to 36 months) were assessed using linear regression and mixed modelling, respectively. Adjusted sex-specific associations of breast feeding with average BAZ from 3 months to 16 years were assessed using generalized estimating equation. Potential confounders were maternal and infant characteristics, and household income.

RESULTS

Among 7367 children, associations of breast feeding with infant growth did not vary by sex, but WAZ gains varied by age. Greater WAZ gains were observed in BF than FF infants from 0 to 3 months but in FF than BF infants from 3 to 9 months. Breast feeding was not associated with overall BAZ from 3 months to 16 years, with no differences by sex.

CONCLUSIONS

Our findings suggest that breast feeding may only have short-term effects on growth. Further studies of the role of breast feeding in other metabolic diseases may be needed.

The factors that influence oral health-related quality of life in 15-year-old children

Background

Several hypotheses on factors that influence oral health-related quality of life (OHRQoL) have been proposed but a consensus has not been reached. This cross-sectional study aimed to analyse the sociodemographic and clinical factors that may influence the OHRQoL of 15-year-old children.

Methods

A representative sample was selected from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. Child Perception Questionnaire (CPQ_11–14, 37 items) including four domains, namely oral symptoms (OS), functional limitations (FL), emotional well-being (EWB), and social well-being (SWB), was used to measure OHRQoL. Adjusted OR was calculated by ordinal logistic regression.

Results

A total of 364 eligible subjects (186 girls, 178 boys) were recruited. The prevalence of caries was higher in girls than in boys (P = 0.013). Compared with girls, boys tended to have a better experience in the domains of EWB, SWB and the total CPQ (adjusted OR = 0.46, 0.59 and 0.61, respectively). Unhealthy periodontal conditions were more prevalent than caries (92.6% vs. 52.7%); moreover, periodontal conditions with CPI scores of 2 had a negative effect on the domain of SWB and the total CPQ (adjusted OR = 1.76 and 1.71, respectively). Only the most severe malocclusion showed an effect on the domain of FL and the total CPQ (adjusted OR = 1.55 and 2.10, respectively). Little effect of family ecosocial factors and caries was found on CPQ scores.

Conclusion

In this study, gender, periodontal status, and malocclusion showed an effect on OHRQoL after adjusting for potential confounders. Boys had less caries and better OHRQoL than girls did. Unhealthy periodontal conditions led to worse social welfares and OHRQoL. The most severe level of malocclusion caused oral functional limitations, hence worse OHRQoL.

The Association of Intergenerational Mismatch With Adiposity and Blood Pressure in Childhood and Adolescence

PURPOSE

An intergenerational "mismatch," a transition from limited to plentiful living conditions over generations, may increase cardiovascular disease risks. In a migrant population within a homogenous culture, we tested the hypothesis that an intergenerational mismatch in childhood living condition is associated with higher body mass index (BMI) and blood pressure in childhood and adolescence.

METHODS

We used data from 6,965 native born Chinese in Hong Kong (participated in "Children of 1997" birth cohort) and migrant Chinese born elsewhere in China in 1997 (N = 9,845). We classified children into those with intergenerational mismatch (child migrants or first-generation migrants) or those without (second+-generation migrants). Generalized estimating equations were used to examine the associations of migration status (child migrants, first-generation migrants or second+-generation migrants) with age- and sex-specific BMI z-score at 8-15 years and age-, sex-, and height-specific blood pressure z-score at 11-13 years, adjusted for sex, month of birth, and age.

RESULTS

Compared with second+-generation migrants, first-generation migrants had higher diastolic blood pressure z-score (.04, 95% confidence interval (CI) .02, .06) and BMI z-score (.12, 95% CI .06, .18), whereas child migrants had higher diastolic blood pressure z-score (.03, 95% CI .01, .05) regardless of age at migration and higher BMI z-score if they had migrated in infancy (.17, 95% CI .11, .23).

CONCLUSION

Different relations for blood pressure and BMI suggest that intergenerational mismatch and proximal exposures may have different impacts on adiposity and blood pressure.

Mode of delivery and child and adolescent psychological well-being: Evidence from Hong Kong's "Children of 1997" birth cohort

Mode of delivery (vaginal or cesarean section) is thought to affect gut microbiota, which in turn may affect psychological well-being. As such, mode of delivery is potentially a modifiable factor for psychological well-being. Here we examined the association of mode of delivery with child and adolescent psychological well-being. We used multivariable linear regression in a population-representative Hong Kong Chinese birth cohort, “Children of 1997,” to examine the adjusted associations of mode of delivery with behavioral problems assessed from parent-reported Rutter score at ~7 (n = 6294) and ~11 years (n = 5598), self-esteem assessed from self-reported Culture-Free Self-Esteem Inventory score at ~11 years (n = 6937) and depressive symptoms assessed from self-reported Patient Health Questionnaire-9 score at ~13 years (n = 5797). Cesarean Section (CS) was associated with children born in private hospitals, boys, and firstborns, higher maternal body mass index, higher maternal age, preeclampsia, higher socioeconomic position (SEP) and maternal birth in Hong Kong. CS was unrelated to behavior, self-esteem and depressive symptoms adjusted for infant characteristics (sex, gestational age, birthweight, parity and breast feeding), maternal characteristics (mother’s age and place of birth) and SEP. In a developed non-Western setting, mode of delivery was not clearly associated with childhood or early adolescent psychological well-being.

Pathways from parental educational attainment to adolescent blood pressure

OBJECTIVES

Lower parental education is associated with higher adolescent blood pressure (BP). We examined the contribution of modifiable risk factors from infancy to adolescence that could potentially explain the link between parental education and SBP and DBP in the offspring.

METHODS

In a prospective Chinese birth cohort, 'Children of 1997' of 5604 adolescents (68% follow-up), we analyzed the relation between parental educational attainment and sex-specific, age-specific and height-specific BP z-scores at ∼13 years. Using mediation analysis, we examined the contribution of household income at birth (both absolute income and relative income deprivation), exposures during infancy (breastfeeding and early life second-hand smoking), lifestyles during childhood (diet, physical activity and screen-time), weight or BMI status during fetal, infancy, childhood and puberty, pubertal stage as well as parental BMI.

RESULTS

We found that adolescent BMI, but not birth weight or infant growth or childhood BMI, mediated the inverse association of parental education with adolescent SBP (proportion mediated: 24%), followed by maternal BMI (proportion mediated: 18%). Factors explaining the link between parental education and DBP were less clear. Absolute income, breastfeeding, childhood diet and physical activity, pubertal stage and paternal BMI did not mediate the association between parental education and adolescent BP.

CONCLUSION

Low parental education is a risk factor for high SBP and, to a lesser extent, DBP in adolescents. Important mediators of this relation include adolescent and maternal body weight.

The association of air pollution with birthweight and gestational age: evidence from Hong Kong's 'Children of 1997' birth cohort

Background

Previous studies from Western settings have found inconsistent associations of air pollutants with birth outcomes, which are open to residual confounding by socioeconomic position (SEP). We assessed this association in the economically developed non-Western setting of Hong Kong, with high levels of air pollution but little social patterning of these outcomes.

Methods

We obtained PM10, SO2, NO and NO2 from monitoring stations, and assessed their associations with birthweight and gestational age in a large population-representative birth cohort 'Children of 1997', using partial least-square regression to account for the colinearity between pollutants.

Results

PM10 (per 5.7 µg/m3 higher) and NO2 (per 10.9 µg/m3 higher) were associated with birthweight lower by 47.0 g (95% confidence interval (CI) 36.2-56.3) and 16.9 g (95% CI 10.8-22.6), respectively; and were associated with gestational age shorter by 2.1 days (95% CI 1.7-2.4) and 0.7 days (95% CI 0.5-0.8), respectively.

Conclusions

Given minimal confounding by SEP in our setting, these findings provide unequivocal evidence of adverse effects of PM10 and NO2 exposure during pregnancy on birthweight and gestational age. Physiological mechanisms need to be better understood to support effective public health action globally.

The factors that influence the oral health-related quality of life in 12-year-old children: baseline study of a longitudinal research

Background

Oral health-related quality of life (OHRQoL) could be affected not only by oral health but also by demographic and ecosocial factors. This research aimed to analyze the sociodemographic and clinical factors that may influence the OHRQoL of 12-year-old children.

Methods

A representative sample was selected from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. Child Perception Questionnaires (CPQ_11–14-ISF:8 and CPQ_11–14-RSF:8) including four domains, namely oral symptoms (OS), functional limitations (FL), emotional well-being (EWB), and social well-being (SWB), were used to measure OHRQoL. Adjusted OR was calculated by ordinal logistic regression.

Results

Totally 589 eligible subjects (305 females, 284 males) were recruited. Males tended to rank higher in OS domain but lower in EWB domain (adjusted OR = 1.89 and 0.67). Mother’s education was linked more closely with children’s CPQ scores. Higher education levels were associated with better quality of life (adjusted OR = 0.45 and 0.37). Household income showed no effect on CPQ scores. Unhealthy periodontal conditions had a negative effect on EWB and total CPQ (adjusted OR = 1.61 and 1.63). High caries experience only had a negative effect on SWB (adjusted OR = 1.60). Malocclusion affected FL, EWB, SWB and total CPQ: all malocclusion severities affected SWB; only severe malocclusions affected FL, EWB and total CPQ.

Conclusion

Males were more tolerant of oral symptoms than females were. Higher levels of mother’s education led to better OHRQoL of their children. Unhealthy periodontal conditions affected emotional well-being, while high caries experience affected social well-being. All malocclusion severities had an effect on social well-being; severe malocclusion further caused functional limitations, worse emotional well-being, and hence worse OHRQoL.

The association of breastfeeding with insulin resistance at 17 years: Prospective observations from Hong Kong's "Children of 1997" birth cohort

Breastfeeding has many benefits for mother and infant. Whether breastfeeding also protects against type 2 diabetes is unclear. To clarify the role of breastfeeding in type 2 diabetes, we assessed the association of breastfeeding with insulin resistance in late adolescence in a birth cohort from a non-Western setting where breastfeeding was not associated with higher socio-economic position. We used multivariable linear regression, with multiple imputation and inverse probability weighting, to examine the adjusted associations of contemporaneously reported feeding in the first 3 months of life (exclusively breastfed, mixed feeding, or always formula-fed) with fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) at 17 years in a subset (n = 710, 8.6% of entire cohort) of the Hong Kong Chinese birth cohort "Children of 1997." We found a graded association of breastfeeding exclusivity in the first 3 months of life with lower fasting insulin and HOMA-IR (p-for-trend < .05), but not fasting glucose, at 17 years. Exclusively breastfed adolescents (7%) had nonsignificantly lowest fasting insulin and HOMA-IR, adjusted for sex, birth weight, parity, length of gestation, pregnancy characteristics, parents' education, and mother's place of birth. Exclusively breastfeeding for 3 months may be causally associated with lower insulin resistance in late adolescence. Further follow-up studies into adulthood are required to clarify the long-term protection of breastfeeding from type 2 diabetes.

Pubertal development in girls by breast cancer family history: the LEGACY girls cohort

Background

Pubertal milestones, such as onset of breast development and menstruation, play an important role in breast cancer etiology. It is unclear if these milestones are different in girls with a first- or second-degree breast cancer family history (BCFH).

Methods

In the LEGACY Girls Study (n = 1040), we examined whether three mother/guardian-reported pubertal milestones (having reached Tanner Stage 2 or higher (T2+) for breast and pubic hair development, and having started menstruation) differed by BCFH. We also examined whether associations between body size and race/ethnicity and pubertal milestones were modified by BCFH. We used mother/guardian reports as the primary measure of pubertal milestones, but also conducted sensitivity analyses using clinical Tanner measurements available for a subcohort (n = 204). We analyzed cross-sectional baseline data with logistic regression models for the entire cohort, and longitudinal data with Weibull survival models for the subcohort of girls that were aged 5–7 years at baseline (n = 258).

Results

BCFH was modestly, but not statistically significantly, associated with Breast T2+ (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 0.88–2.10), with a stronger association seen in the subcohort of girls with clinical breast Tanner staging (OR = 2.20, 95% CI = 0.91–5.32). In a longitudinal analysis of girls who were aged 5–7 years at baseline, BCFH was associated with a 50% increased rate of having early breast development (hazard ratio (HR) = 1.49, 95% CI = 1.0–2.21). This association increased to twofold in girls who were not overweight at baseline (HR = 2.04, 95% CI = 1.29–3.21). BCFH was not associated with pubic hair development and post-menarche status. The median interval between onset of breast development and menarche was longer for BCFH+ than BCFH– girls (2.3 versus 1.7 years), suggesting a slower developmental tempo for BCFH+ girls. Associations between pubertal milestones and body size and race/ethnicity were similar in girls with or without a BCFH. For example, weight was positively associated with Breast T2+ in both girls with (OR = 1.06 per 1 kg, 95% CI = 1.03–1.10) and without (OR = 1.14 per 1 kg, 95% CI = 1.04–1.24) a BCFH.

Conclusions

These results suggest that BCFH may be related to earlier breast development and slower pubertal tempo independent of body size and race/ethnicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0849-y) contains supplementary material, which is available to authorized users.