Cardiovascular outcomes 50 years after antenatal exposure to betamethasone: Follow-up of a randomised double-blind, placebo-controlled trial.

BACKGROUND: Antenatal corticosteroids for women at risk of preterm birth reduce neonatal morbidity and mortality, but there is limited evidence regarding their effects on long-term health. This study assessed cardiovascular outcomes at 50 years after antenatal exposure to corticosteroids. METHODS AND FINDINGS: We assessed the adult offspring of women who participated in the first randomised, double-blind, placebo-controlled trial of antenatal betamethasone for the prevention of neonatal respiratory distress syndrome (RDS) (1969 to 1974). The first 717 mothers received 2 intramuscular injections of 12 mg betamethasone or placebo 24 h apart and the subsequent 398 received 2 injections of 24 mg betamethasone or equivalent volume of placebo. Follow-up included a health questionnaire and consent to access administrative data sources. The co-primary outcomes were the prevalence of cardiovascular risk factors (any of hypertension, hyperlipidaemia, diabetes mellitus, gestational diabetes mellitus, or prediabetes) and age at first major adverse cardiovascular event (MACE) (cardiovascular death, myocardial infarction, coronary revascularisation, stroke, admission for peripheral vascular disease, and admission for heart failure). Analyses were adjusted for gestational age at entry, sex, and clustering. Of 1,218 infants born to 1,115 mothers, we followed up 424 (46% of survivors; 212 [50%] female) at mean (standard deviation) age 49.3 (1.0) years. There were no differences between those exposed to betamethasone or placebo for cardiovascular risk factors (159/229 [69.4%] versus 131/195 [67.2%]; adjusted relative risk 1.02, 95% confidence interval [CI] [0.89, 1.18;]; p = 0.735) or age at first MACE (adjusted hazard ratio 0.58, 95% CI [0.23, 1.49]; p = 0.261). There were also no differences in the components of these composite outcomes or in any of the other secondary outcomes. Key limitations were follow-up rate and lack of in-person assessments. CONCLUSIONS: There is no evidence that antenatal corticosteroids increase the prevalence of cardiovascular risk factors or incidence of cardiovascular events up to 50 years of age. Established benefits of antenatal corticosteroids are not outweighed by an increase in adult cardiovascular disease.

Case identification of non-traumatic brain injury in youth using linked population data.

BACKGROUND: Population-level administrative data provides a cost-effective means of monitoring health outcomes and service needs of clinical populations. This study aimed to present a method for case identification of non-traumatic brain injury in population-level data and to examine the association with sociodemographic factors. METHODS: An estimated resident population of youth aged 0-24 years was constructed using population-level datasets within the New Zealand Integrated Data Infrastructure. A clinical consensus committee reviewed the International Classification of Diseases Ninth and Tenth Editions codes and Read codes for inclusion in a case definition. Cases were those with at least one non-traumatic brain injury code present in the five years up until 30 June 2018 in one of four databases in the Integrated Data Infrastructure. Rates of non-traumatic brain injury were examined, both including and excluding birth injury codes and across age, sex, ethnicity, and socioeconomic deprivation groups. RESULTS: Of the 1 579 089 youth aged 0-24 years on 30 June 2018, 8154 (0.52%) were identified as having one of the brain injury codes in the five-years to 30 June 2018. Rates of non-traumatic brain injury were higher in males, children aged 0-4 years, Maori and Pacific young people, and youth living with high levels of social deprivation. CONCLUSION: This study presents a comprehensive method for case identification of non-traumatic brain injury using national population-level administrative data.

Kumanu Tangata: the aftermatch study - protocol to examine the health outcomes of high-level male rugby union players using linked administrative data.

There is increasing interest in the potential long-term outcomes of participation in contact and collision sports, driven by evidence of higher rates of neurodegenerative diseases among former athletes. Recent research has capitalised on large-scale administrative health data to examine health outcomes in contact sport athletes. However, there is limited research on outcomes associated with participation in rugby union, a contact sport with a relatively high incidence of head trauma and musculoskeletal injuries. Additionally, there is scope to investigate a greater range of health outcomes using large, population-based administrative data. The Kumanu Tangata project is a retrospective cohort study that will use linked information from the New Zealand Rugby Register and health records within a comprehensive deidentified whole-population administrative research database known as the Integrated Data Infrastructure. First-class male rugby union players (N=13 227) will be compared with a general population comparison group (N=2 438 484; weighting will be applied due to demographic differences) on a range of mortality and morbidity outcomes (neurodegenerative diseases, musculoskeletal conditions, chronic physical conditions, mental health outcomes). A range of player-specific variables will also be investigated as risk factors. Analyses will consist primarily of Cox proportional hazards models. Ethics approval for the study has been granted by the Auckland Health Research Ethics Committee (Ref. AH23203). Primary research dissemination will be via peer-reviewed journal articles.

Suicides, drug poisonings, and alcohol-related deaths cluster with health and social disadvantage in 4.1 million citizens from two nations.

BACKGROUND: Deaths from suicides, drug poisonings, and alcohol-related diseases ('deaths of despair') are well-documented among working-age Americans, and have been hypothesized to be largely specific to the U.S. However, support for this assertion-and associated policies to reduce premature mortality-requires tests concerning these deaths in other industrialized countries, with different institutional contexts. We tested whether the concentration and accumulation of health and social disadvantage forecasts deaths of despair, in New Zealand and Denmark. METHODS: We used nationwide administrative data. Our observation period was 10 years (NZ = July 2006-June 2016, Denmark = January 2007-December 2016). We identified all NZ-born and Danish-born individuals aged 25-64 in the last observation year (NZ = 1 555 902, Denmark = 2 541 758). We ascertained measures of disadvantage (public-hospital stays for physical- and mental-health difficulties, social-welfare benefit-use, and criminal convictions) across the first nine years. We ascertained deaths from suicide, drugs, alcohol, and all other causes in the last year. RESULTS: Deaths of despair clustered within a population segment that disproportionately experienced multiple disadvantages. In both countries, individuals in the top 5% of the population in multiple health- and social-service sectors were at elevated risk for deaths from suicide, drugs, and alcohol, and deaths from other causes. Associations were evident across sex and age. CONCLUSIONS: Deaths of despair are a marker of inequalities in countries beyond the U.S. with robust social-safety nets, nationwide healthcare, and strong pharmaceutical regulations. These deaths cluster within a highly disadvantaged population segment identifiable within health- and social-service systems.

Social isolation from childhood to mid-adulthood: is there an association with older brain age?

BACKGROUND: Older brain age - as estimated from structural MRI data - is known to be associated with detrimental mental and physical health outcomes in older adults. Social isolation, which has similar detrimental effects on health, may be associated with accelerated brain aging though little is known about how different trajectories of social isolation across the life course moderate this association. We examined the associations between social isolation trajectories from age 5 to age 38 and brain age assessed at age 45. METHODS: We previously created a typology of social isolation based on onset during the life course and persistence into adulthood, using group-based trajectory analysis of longitudinal data from a New Zealand birth cohort. The typology comprises four groups: 'never-isolated', 'adult-only', 'child-only', and persistent 'child-adult' isolation. A brain age gap estimate (brainAGE) - the difference between predicted age from structural MRI date and chronological age - was derived at age 45. We undertook analyses of brainAGE with trajectory group as the predictor, adjusting for sex, family socio-economic status, and a range of familial and child-behavioral factors. RESULTS: Older brain age in mid-adulthood was associated with trajectories of social isolation after adjustment for family and child confounders, particularly for the 'adult-only' group compared to the 'never-isolated' group. CONCLUSIONS: Although our findings are associational, they indicate that preventing social isolation, particularly in mid-adulthood, may help to avert accelerated brain aging associated with negative health outcomes later in life.

Regional variation in sudden unexpected death in infancy in New Zealand.

AIM: To estimate the relative risk of sudden unexpected death in infancy (SUDI) by district health board (DHB) in New Zealand after adjustment for socio-economic deprivation, ethnicity and other demographic factors. METHODS: We conducted a population-based cohort study using data from the Integrated Data Infrastructure, a large research database containing linked data from a range of government agencies. The study population was all live births and their mothers in New Zealand from 2012 to 2018. The exposure of interest was DHB. The outcome was SUDI. RESULTS: There were 418 068 live births in New Zealand from 2012 to 2018, and of these 415 401 (99.4%) had valid DHB data. There was considerable variation in the proportion of infants in each DHB living in the most deprived decile varying from 4.5% in Nelson, West Coast and Canterbury to 29.7% in Counties Manukau. There were 267 SUDI cases, giving an overall rate of 0.64/1000 live births during the study period (2012-2018). The SUDI rate varied from 1.11/1000 in Northland to 0.30/1000 in Waitemata and Auckland. Counties Manukau had the largest number of deaths (n = 54; rate = 1.08/1000). Five DHB regions had increased risk of SUDI compared to the reference group but, after adjustment, no DHB was significantly increased. CONCLUSIONS: This study found that there is marked variation in SUDI risk by DHB, but this is explained by socio-economic and demographic variation within DHBs. This study emphasises the importance of the contribution of social determinants of health to SUDI.

Maternal mental health and substance use disorders in sudden unexpected death in infancy using routinely collected health data in New Zealand, 2000-2016.

BACKGROUND: Mortality from sudden unexpected death in infancy (SUDI) has declined dramatically since the 'Back to Sleep' campaign. Deaths now are more prevalent in those with socioeconomic disadvantage. The investigation of SUDI frequently identifies parents that have mental health or drug, alcohol and addiction problems. AIMS: To estimate the prevalence of maternal mental health and substance use disorders and assess the magnitude of their risk for SUDI. METHODS: We conducted a population-based cohort study using data from the Integrated Data Infrastructure (IDI), a large research database containing linked data from a range of government agencies. The study population was all live births and their mothers in New Zealand from 2000 to 2016. The exposures of interest were maternal mental health problems and maternal substance use disorders in the year prior to the birth. The outcome was deaths from SUDI. RESULTS: The total population was 1086 504 live births and of these 1078 811 (99.3%) were able to be linked to other data sets within the IDI. The prevalence of maternal mental health problems in the total population was 5.2% and substance use disorder was 0.7%. There were 42 deaths from SUDI (0.75/1000) that were exposed to maternal mental illness and 864 deaths (0.84/1000) that were not exposed (adjusted relative risk (aRR)=1.23, 95% CI 0.90 to 1.68). There were 21 deaths from SUDI (2.67/1000) that were exposed to maternal substance use disorders and 885 (0.83/1000) that were not exposed (aRR=1.82, 95% CI 1.17 to 2.83). CONCLUSIONS: Maternal substance use disorders, but not maternal mental health problems, in the year prior to the child's birth was associated with an increased risk of SUDI. However, the numbers that are affected are small and the effect size moderate. This group of women should receive additional SUDI prevention services and Safe Sleep advice.

Prevalence of Loneliness and Its Association With General and Health-Related Measures of Subjective Well-Being in a Longitudinal Bicultural Cohort of Older Adults in Advanced Age Living in New Zealand: LiLACS NZ.

OBJECTIVES: There is evidence that loneliness is detrimental to the subjective well-being of older adults. However, little is known on this topic for the cohort of those in advanced age (80 years or older), which today is the fastest-growing age group in the New Zealand population. We examined the relationships between loneliness and selected subjective well-being outcomes over 5 years. METHODS: We used a regional, bicultural sample of those in advanced age from 2010 to 2015 (Life and Living in Advanced Age: a Cohort Study in New Zealand). The first wave enrolled 937 people (92% of whom were living in the community): 421 Maori (Indigenous New Zealanders aged 80-90 years) and 516 non-Maori aged 85 years. We applied standard regression techniques to baseline data and mixed-effects models to longitudinal data, while adjusting for sociodemographic factors. RESULTS: For both Maori and non-Maori, strong negative associations between loneliness and subjective well-being were found at baseline. In longitudinal analyses, we found that loneliness was negatively associated with life satisfaction as well as with mental health-related quality of life. DISCUSSION: Our findings of adverse impacts on subjective well-being corroborate other evidence, highlighting loneliness as a prime candidate for intervention-appropriate to cultural context-to improve well-being for adults in advanced age.

Association Between High-Need Education-Based Funding and School Suspension Rates for Autistic Students in New Zealand.

Importance: Autistic students often experience poor educational outcomes that have implications for later life, including unemployment, interactions with the criminal justice system, increased risk for substance abuse, and low socioeconomic status. Improving educational outcomes is critical for ensuring that autistic young people can reach their potential. Objective: To quantify differences in suspension rates between autistic and nonautistic students and to assess whether high-need education-based funding for autistic students is associated with reduced rates of school suspension. Design, Setting, and Participants: This national cohort study used linked health and education data from New Zealand's Integrated Data Infrastructure. Data were obtained for students aged 5 to 16 years from January 1 to December 31, 2018, and analyzed July 7, 2021, to January 1, 2022. A novel case identification method was used to identify autistic students. Exposures: High-need education-based funding (Ongoing Resourcing Scheme [ORS]) obtained before 2019. Main Outcomes and Measures: Rates of suspension from school. Crude and adjusted analyses of the association between suspension rates and autism among the full population with adjustment made for sociodemographic characteristics (sex, age, ethnicity, deprivation, and urban or rural profile of residence) were conducted using complete-case, 2-level random intercept logistic multivariable regressions. To assess the association between ORS funding and suspension, analysis was restricted to autistic students. Results: Of the 736 911 students in the study population, 9741 (1.3%) were identified as autistic (median [SD] age, 10 [3.2] years; 7710 [79.1%] boys), and 727 170 (98.7%) as nonautistic (median [SD] age, 10 [3.4] years; 369 777 [50.9%] boys). School suspension was experienced by 504 autistic students (5.2%) and 13 845 nonautistic students (1.9%). After adjustment for demographic characteristics, autistic students had significantly higher odds of suspension than their nonautistic peers (adjusted odds ratio, 2.81; 95% CI, 2.55-3.11). Of the 9741 autistic students, 2895 (29.7%) received high-need education-based (ORS) funding. Suspensions were experienced by 57 autistic students (2.0%) with high-need funding and 447 autistic students (6.5%) without high-need funding. After adjustment for demographic characteristics, co-occurring conditions, and level of disability support need, autistic students with high-need funding had significantly lower odds of suspension than autistic students without high-need funding (adjusted odds ratio, 0.29; 95% CI, 0.21-0.40). Conclusions and Relevance: In this cohort study, the findings of disparities in suspension rates between autistic and nonautistic students underscore the challenges faced in providing inclusive education for all young people, regardless of disability status. This study found that high-need funding was associated with reduced suspension rates among autistic students, suggesting that if appropriate supports are afforded to autistic students, a more inclusive education can be provided.

Longitudinal Associations of Mental Disorders With Dementia: 30-Year Analysis of 1.7 Million New Zealand Citizens.

IMPORTANCE: Mental disorders are an underappreciated category of modifiable risk factors for dementia. Developing an evidence base about the link between mental disorders and dementia risk requires studies that use large, representative samples, consider the full range of psychiatric conditions, ascertain mental disorders from early life, use long follow-ups, and distinguish between Alzheimer disease and related dementias. OBJECTIVE: To test whether mental disorders antedate dementia across 3 decades of observation. DESIGN, SETTING, AND PARTICIPANTS: This population-based administrative register study of mental disorders and Alzheimer disease and related dementias included all individuals born in New Zealand between 1928 and 1967 who resided in the country for any time during the 30-year observation period between July 1988 and June 2018. Data were from the New Zealand Integrated Data Infrastructure, a collection of whole-of-population administrative data sources linked at the individual level. Data were analyzed from October 2020 to November 2021. EXPOSURES: Diagnoses of mental disorders were ascertained from public-hospital records. MAIN OUTCOMES AND MEASURES: Diagnoses of dementia were ascertained from public-hospital records, mortality records, and pharmaceutical records. RESULTS: Of 1 711 386 included individuals, 866 301 (50.6%) were male, and individuals were aged 21 to 60 years at baseline. Relative to individuals without a mental disorder, those with a mental disorder were at increased risk of developing subsequent dementia (relative risk [RR], 4.24; 95% CI, 4.07-4.42; hazard ratio, 6.49; 95% CI, 6.25-6.73). Among individuals with dementia, those with a mental disorder developed dementia a mean of 5.60 years (95% CI, 5.31-5.90) earlier than those without a mental disorder. Associations held across sex and age and after accounting for preexisting chronic physical diseases and socioeconomic deprivation. Associations were present across different types of mental disorders and self-harm behavior (RRs ranged from 2.93 [95% CI, 2.66-3.21] for neurotic disorders to 6.20 [95% CI, 5.67-6.78] for psychotic disorders), and were evident for Alzheimer disease (RR, 2.76; 95% CI, 2.45-3.11) and all other dementias (RR, 5.85; 95% CI, 5.58-6.13). CONCLUSIONS AND RELEVANCE: In this study, mental disorders were associated with the onset of dementia in the population. Ameliorating mental disorders in early life might also ameliorate neurodegenerative conditions and extend quality of life in old age.

Further reductions in the prevalence of obesity in 4-year-old New Zealand children from 2017 to 2019.

OBJECTIVE: To examine whether the prevalence of age- and sex-adjusted BMI at, or above, the 85th, 95th and 99.7th percentiles continues to decline in New Zealand preschool children, over time. METHODS: As part of a national screening programme, 438,972 New Zealand 4-year-old children had their height and weight measured between 2011 and 2019. Age- and sex-adjusted BMI was calculated using WHO Growth Standards and the prevalence of children at, or above, the 85th, 95th, and 99.7th percentiles and at, or below, the 2nd percentile were determined. Log-binomial models were used to estimate linear time trends of ≥85th, ≥95th and ≥99.7th percentiles for the overall sample and separately by sex, deprivation, ethnicity and urban-rural classification. RESULTS: The percentage of children at, or above, the 85th, 95th and 99.7th percentile reduced by 4.9% [95% CI: 4.1%, 5.7%], 3.5% [95% CI: 2.9%, 4.1%], and 0.9% [95% CI: 0.7%, 1.2%], respectively, between '2011/12' and '2018/19'. There was evidence of a decreasing linear trend (risk reduction, per year) for the percentage of children ≥85th (risk ratio (RR): 0.980 [95% CI: 0.978, 0.982]), ≥95th (RR: 0.966 [95% CI: 0.962, 0.969]) and ≥99.7th (RR: 0.957 [95% CI: 0.950, 0.964]) percentiles. Downward trends were also evident across all socioeconomic indicators (sex, ethnicity, deprivation, and urban-rural classification), for each of the BMI thresholds. Larger absolute decreases were evident for children residing in the most deprived compared with the least deprived areas, at each BMI threshold. There appeared to be no consistent trend for the percentage of children ≤2nd percentile. CONCLUSIONS: Reassuringly, continued declines of children with age- and sex-adjusted BMI at, or above, the 85th, 95th and 99.7th percentiles are occurring over time, overall and across all sociodemographic indicators, with little evidence for consistent trends in the prevalence of children at, or below, the 2nd percentile.

Use of Population-Level Administrative Data in Developmental Science.

Population-level administrative data-data on individuals' interactions with administrative systems (e.g., health, criminal justice, and education)-have substantially advanced our understanding of life-course development. In this review, we focus on five areas where research using these data has made significant contributions to developmental science: (a) understanding small or difficult-to-study populations, (b) evaluating intergenerational and family influences, (c) enabling estimation of causal effects through natural experiments and regional comparisons, (d) identifying individuals at risk for negative developmental outcomes, and (e) assessing neighborhood and environmental influences. Further advances will be made by linking prospective surveys to administrative data to expand the range of developmental questions that can be tested; supporting efforts to establish new linked administrative data resources, including in developing countries; and conducting cross-national comparisons to test findings' generalizability. New administrative data initiatives should involve consultation with population subgroups including vulnerable groups, efforts to obtain social license, and strong ethical oversight and governance arrangements.

Trajectories of childhood social isolation in a nationally representative cohort: Associations with antecedents and early adulthood outcomes.

Background: This study examined early life antecedents of childhood social isolation, whether these factors accounted for poor outcomes of isolated children, and how these associations varied according to patterns of stability and change in childhood isolation. Methods: Participants included 2232 children from the Environmental Risk (E-Risk) Longitudinal Twin Study. We conducted growth mixture modelling (GMM) on combined parent and teacher reports of children's social isolation when children were 5, 7, 10 and 12 years, and we assessed associations with age-5 antecedents and age-18 outcomes using regression analyses. Results: We identified three linear developmental trajectories of increasing (4.75%), decreasing (5.25%) and low stable (90.00%) social isolation. Age-5 attention deficit hyperactivity disorder (ADHD) symptoms, emotional problems, prosocial behaviours, maternal personality (openness) and size of school were associated with the decreasing trajectory of social isolation. When controlling for these antecedents, increasingly isolated children were still more likely to experience ADHD symptoms, loneliness, lower job optimism and lower physical activity at age 18. Conclusions: Isolated children follow distinct patterns of change over childhood and isolation seems most detrimental to health at the time it is experienced. Social isolation can be a valuable indicator of co-occurring problems and provide targets for mental health intervention in young people.

Longitudinal Associations of Mental Disorders With Physical Diseases and Mortality Among 2.3 Million New Zealand Citizens.

Importance: Excess risk of physical disease and mortality has been observed among individuals with psychiatric conditions, suggesting that ameliorating mental disorders might also be associated with ameliorating the later onset of physical disability and early mortality. However, the temporal association between mental disorders and physical diseases remains unclear, as many studies have relied on retrospective recall, used cross-sectional designs or prospective designs with limited follow-up periods, or given inadequate consideration to preexisting physical illnesses. Objective: To examine whether mental disorders are associated with subsequent physical diseases and mortality across 3 decades of observation. Design, Setting, and Participants: This population-based cohort study used data from the New Zealand Integrated Data Infrastructure, a collection of nationwide administrative data sources linked at the individual level, to identify mental disorders, physical diseases, and deaths recorded between July 1, 1988, and June 30, 2018, in the population of New Zealand. All individuals born in New Zealand between January 1, 1928, and December 31, 1978, who resided in the country at any time during the 30-year observation period were included in the analysis. Data were analyzed from July 2019 to November 2020. Exposures: Nationwide administrative records of mental disorder diagnoses made in public hospitals. Main Outcomes and Measures: Chronic physical disease diagnoses made in public hospitals, deaths, and health care use. Results: The study population comprised 2 349 897 individuals (1 191 981 men [50.7%]; age range at baseline, 10-60 years). Individuals with a mental disorder developed subsequent physical diseases at younger ages (hazard ratio [HR], 2.33; 95% CI, 2.30-2.36) and died at younger ages (HR, 3.80; 95% CI, 3.72-3.89) than those without a mental disorder. These associations remained across sex and age and after accounting for preexisting physical diseases. Associations were observed across different types of mental disorders and self-harm behavior (relative risks, 1.78-2.43; P < .001 for all comparisons). Mental disorders were associated with the onset of physical diseases and the accumulation of physical disease diagnoses (incidence rate ratio [IRR], 2.00; 95% CI, 1.98-2.03), a higher number of hospitalizations (IRR, 2.43; 95% CI, 2.39-2.48), longer hospital stays for treatment (IRR, 2.70; 95% CI, 2.62-2.79), and higher associated health care costs (b = 0.115; 95% CI, 0.112-0.118). Conclusions and Relevance: In this study, mental disorders were likely to begin and peak in young adulthood, and they antedated physical diseases and early mortality in the population. These findings suggest that ameliorating mental disorders may have implications for improving the length and quality of life and for reducing the health care costs associated with physical diseases.

The relationship between income poverty and child hospitalisations in New Zealand: Evidence from longitudinal household panel data and Census data.

BACKGROUND: Very little high quality evidence exists on the causal relationship between income poverty and childhood health. We provide a comprehensive overview of the association between household income poverty and hospitalisations for children. METHODS: We used New Zealand's Integrated Data Infrastructure (IDI) to link income poverty data from the Survey of Family, Income and Employment (SoFIE; n = 21,759 households) and the 2013 New Zealand Census (n = 523,302 households) to publicly funded hospital records of children aged 0-17 (SoFIE: n = 39,459; Census, n = 986,901). Poverty was defined as equivalised household income below 60% of the median income, calculated both before and after housing costs, and using both self-reported and tax-recorded income. RESULTS: Correlations for the association between income poverty and hospitalisation were small (ranging from 0.02 to 0.05) and risk ratios were less than 1.35 for all but the rarest outcome-oral health hospitalisation. Weak or absent associations were apparent across age groups, waves of data collection, cumulative effects, and for estimates generated from fixed effects models and random effect models adjusted for age and ethnicity. Alternative measures of deprivation (area-level deprivation and material deprivation) showed stronger associations with hospitalisations (risk ratios ranged from 1.27-2.55) than income-based poverty measures. CONCLUSION: Income poverty is at best weakly associated with hospitalisation in childhood. Measures of deprivation may have a stronger association. Income measures alone may not be sufficient to capture the diversity of household economic circumstances when assessing the poverty-health relationship.

Birth by caesarean section and educational achievement in adolescents.

BACKGROUND: Birth by caesarean section has been shown to alter the composition of the early infant gut microbiota and postulated to influence cognitive outcomes via the gut-brain axis. AIMS: To determine whether birth by caesarean section is associated with secondary school educational achievement. METHODS: Whole-population administrative data were used from anonymised individual level linkage of birth records to educational and health information from the New Zealand Integrated Data Infrastructure (IDI). Participants were 111 843 children born between 1 January 1996 and 31 December 1998 for whom mode of delivery information was available from International Classification of Diseases 9th edition codes in maternal records. The National Certificate of Educational Achievement (NCEA) is the main secondary school qualification undertaken by New Zealand students. Multivariable linear regression models were used to examine the association between mode of delivery and educational achievement. A family fixed effect analysis compared educational achievement outcomes in sibling pairs where one sibling was delivered by caesarean section and one delivered vaginally. RESULTS: After adjustment for potential confounders, there was no significant association between mode of delivery and achievement of university entrance (odds ratio = 0.98, 95% CI: 0.94-1.02). NCEA percentile scores were lower in caesarean born infants (Estimate = -0.37, 95% CI: -0.69 to -0.06)). However, in the fixed effect sibling analysis caesarean section was no longer significantly associated with NCEA percentile scores. CONCLUSIONS: We find that caesarean section is not related to educational outcomes, suggesting that even if the infant gut microbiota is altered in caesarean section, it does not appear to have a measurable impact on adolescent academic achievement.

Associations of Prenatal and Childhood Antibiotic Exposure With Obesity at Age 4 Years.

Importance: Although antibiotics are associated with obesity in animal models, the evidence in humans is conflicting. Objective: To assess whether antibiotic exposure during pregnancy and/or early childhood is associated with the development of childhood obesity, focusing particularly on siblings and twins. Design, Setting, and Participants: This cross-sectional national study included 284 211 participants (132 852 mothers and 151 359 children) in New Zealand. Data analyses were performed for 150 699 children for whom data were available, 30 696 siblings, and 4188 twins using covariate-adjusted analyses, and for 6249 siblings and 522 twins with discordant outcomes using fixed-effects analyses. Data analysis was performed November 2017 to March 2019. Exposure: Exposure to antibiotics during pregnancy and/or early childhood. Main Outcomes and Measures: The main outcome is odds of obesity at age 4 years. Anthropometric data from children born between July 2008 and June 2011 were obtained from the B4 School Check, a national health screening program that records the height and weight of 4-year-old children in New Zealand. These data were linked to antibiotics (pharmaceutical records) dispensed to women before conception and during all 3 trimesters of pregnancy and to their children from birth until age 2 years. Results: The overall study population consisted of 132 852 mothers and 151 359 children (77 610 [51.3%] boys) who were aged 4 to 5 years when their anthropometrical measurements were assessed. Antibiotic exposure was common, with at least 1 course dispensed to 35.7% of mothers during pregnancy and 82.3% of children during the first 2 years of life. Results from covariate-adjusted analyses showed that both prenatal and early childhood exposures to antibiotics were independently associated with obesity at age 4 years, in a dose-dependent manner. Every additional course of antibiotics dispensed to the mothers yielded an adjusted odds ratio (aOR) of obesity in their children (siblings) of 1.02 (95% CI, 0.99-1.06), which was similar to the odds across pregnancy for the whole population (aOR, 1.06; 95% CI, 1.04-1.07). For the child's exposure, the aOR for the association between antibiotic exposure and obesity was 1.04 (95% CI, 1.03-1.05) among siblings and 1.05 (95% CI, 1.02-1.09) among twins. However, fixed-effects analyses of siblings and twins showed no associations between antibiotic exposure and obesity, with aORs of 0.95 (95% CI, 0.90-1.00) for maternal exposure, 1.02 (95% CI, 0.99-1.04) for child's exposure, and 0.91 (95% CI, 0.81-1.02) for twins' exposure. Conclusions and Relevance: Although covariate-adjusted analyses demonstrated an association between antibiotic exposure and odds of obesity, further analyses of siblings and twins with discordant outcomes showed no associations. Thus, these discordant results likely reflect unmeasured confounding factors.

Clustering of health, crime and social-welfare inequality in 4 million citizens from two nations.

Health and social scientists have documented the hospital revolving-door problem, the concentration of crime, and long-term welfare dependence. Have these distinct fields identified the same citizens? Using administrative databases linked to 1.7 million New Zealanders, we quantified and monetized inequality in distributions of health and social problems and tested whether they aggregate within individuals. Marked inequality was observed: Gini coefficients equalled 0.96 for criminal convictions, 0.91 for public-hospital nights, 0.86 for welfare benefits, 0.74 for prescription-drug fills and 0.54 for injury-insurance claims. Marked aggregation was uncovered: a small population segment accounted for a disproportionate share of use-events and costs across multiple sectors. These findings were replicated in 2.3 million Danes. We then integrated the New Zealand databases with the four-decade-long Dunedin Study. The high-need/high-cost population segment experienced early-life factors that reduce workforce readiness, including low education and poor mental health. In midlife they reported low life satisfaction. Investing in young people's education and training potential could reduce health and social inequalities and enhance population wellbeing.

Decomposing ethnic differences in body mass index and obesity rates among New Zealand pre-schoolers.

OBJECTIVE: To determine the extent to which ethnic differences in BMI Z-scores and obesity rates could be explained by the differential distribution of demographic (e.g. age), familial (e.g. family income), area (e.g. area deprivation), parental (e.g. immigration status), and birth (e.g. gestational age) characteristics across ethnic groups. METHODS: We used data on 4-year-old children born in New Zealand who attended the B4 School Check between the fiscal years of 2010/2011 to 2015/2016, who were resident in the country when the 2013 census was completed (n = 253,260). We implemented an Oaxaca-Blinder decomposition to explain differences in BMI Z-score and obesity between Maori (n = 63,061) and European (n = 139,546) children, and Pacific (n = 21,527) and European children. RESULTS: Overall, 15.2% of the children were obese and mean BMI Z-score was 0.66 (SD = 1.04). The Oaxaca-Blinder decomposition demonstrated that the difference in obesity rates between Maori and European children would halve if Maori children experienced the same familial and area level conditions as Europeans. If Pacific children had the same characteristics as European children, differences in obesity rates would reduce by approximately one third, but differences in mean BMI Z-scores would only reduce by 16.1%. CONCLUSION: The differential distribution of familial, parental, area, and birth characteristics across ethnic groups explain a substantial percentage of the ethnic differences in obesity, especially for Maori compared to European children. However, marked disparities remain.