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, Māori and Pacific young people, and youth living with high levels of social deprivation.
CONCLUSIONS: This study presents a comprehensive method for case identification of non-traumatic brain injury using national population-level administrative data.

OBJECTIVE: Children with migrant and refugee backgrounds may experience immunisation inequities due to barriers to accessing and accepting vaccines. In Aotearoa New Zealand (NZ), national reporting can mask inequities in coverage by migration background. This study explored paediatric COVID-19 vaccine uptake among children with migrant and refugee backgrounds.
METHODS: This population-level retrospective cohort study compared rates and determinants of paediatric COVID-19 vaccine uptake as of July 2022 amongst migrant and non-migrant children who were aged between 5 and 11 years as of January 2022. Linked de-identified administrative and health data available in Statistics NZ\'s Integrated Data Infrastructure were used, and univariate and multivariable logistic regression were conducted to determine associations.
RESULTS: Of the total study population (N = 451,323), 3.5% were overseas-born migrant children, 31.3% were NZ-born migrant children, and 65.3% were NZ-born non-migrant children. Only 50.8% (229,164 out of 451,323) of children had received at least one dose. Migrant children were significantly more likely to have received a COVID-19 vaccination than non-migrant children. Logistic modelling revealed that all factors, including ethnicity, gender, age, family type, household income, deprivation, region, parent COVID-19 vaccination status, and child\'s previous COVID-19 infection, significantly influenced COVID-19 vaccine uptake. The largest contributing factor was parents\' COVID-19 vaccination status.
CONCLUSIONS: The findings suggest that NZ\'s paediatric COVID-19 vaccination programme was able to address logistical and motivational barriers commonly identified amongst migrants and refugees.
CONCLUSIONS: As parents\' vaccination status is an important factor in vaccinating their own children, continuous efforts are needed to support confident parental COVID-19 vaccine decision-making. To address social inequities, engagement with marginalised communities to co-design tailored and localised approaches is recommended.

Migrants and refugees generally experience immunization inequities compared to their host populations. Childhood vaccination coverage rates are influenced by a complex set of interrelated factors, including child and parental nativity. Coverage rates for MMR, pertussis, and HPV vaccines were compared among children born in Aotearoa New Zealand (NZ) of overseas-born parents or NZ-born parents. A nationwide retrospective cohort study was conducted using linked, de-identified data. Logistic regression models examined the most influential factors contributing to differences in timely vaccine uptake. Of the total study population who had received all scheduled vaccines (N = 760,269), 32.9% were children of migrant parents. Children of migrant parents had higher rates of complete and timely uptake for MMR, pertussis, and HPV vaccinations compared to non-migrant children. NZ-born children of migrant parents were significantly more likely to receive MMR and pertussis-containing vaccines on-time compared to those of non-migrants. All included factors, except for the child\'s gender and parents\' English ability, significantly influenced vaccine uptake. Among NZ-born children of migrant parents, additional logistic modeling found significant differences based on parental duration of residence, visa group, and region of nationality. Findings point to the importance of differentiating between parent versus child nativity when examining immunization coverage. While vaccination rates were higher for NZ-born children of migrant parents, compared to non-migrant parents, timely coverage rates across both groups were below national targets. Continued efforts are needed to improve timely immunization service delivery to address suboptimal and inequitable coverage.

To examine criminal justice system (CJS) interactions and pathways through the justice system for young adults with ADHD compared to young adults without ADHD.
Nationwide 3-year birth cohort study using linked health and CJS data. Cox proportional hazards models were employed to examine associations between ADHD and police proceedings, court charges, court convictions, and incarcerations.
Young adults with ADHD were significantly more likely to interact with the CJS including police proceedings (hazard ratio [HR], 2.1 95% CI [2.0, 2.2]) court charges (HR, 2.2 95% CI [2.1, 2.3]), court convictions (HR, 2.3 95% CI [2.2, 2.4]), and incarceration (HR, 4.8 95% CI [4.3, 5.4]).
Young adults with ADHD are overrepresented at all stages of the CJS. Results highlight the importance of early identification and responsivity to ADHD within the CJS and suggest that the NZ justice system may require changes to both areas to ensure that young individuals with ADHD receive equitable access to, and treatment within, the CJS.

Mental health conditions often arise during adolescence, are multifaceted in aetiology, and may be related to the type of environment in which young people reside. This study used nationwide population-level data to investigate whether the environment a young person grows up in is associated with their mental health.
Data were extracted from the Integrated Data Infrastructure (IDI), a large nationwide research repository, for 917,211 young people (aged 10-24 years) including sociodemographic and mental health data (i.e. emotional, behavioural, substance problems, and self-harm). Environmental data were sourced from the nationwide area-based Healthy Location Index (HLI), which has comprehensive data on the location of several health-constraining (i.e. fast-food outlets) and health-promoting features (i.e. physical activity facilities). Environments were classified as: i) health-promoting, ii) health-constraining, or iii) neither. Associations between the HLI and mental health were investigated using multi-level mixed effects logistic regression modelling.
Overall, there was evidence of an association between the environment a young person resided in and their mental health. Young people residing in health-constraining environments had higher odds of any mental health condition (Adjusted Odds Ratio (AOR) = 1.020 [1.001, 1.040]) and any emotional condition (AOR = 1.037 [1.012, 1.062]). Young people residing in health-promoting environments had lower odds of substance problems (AOR = 0.950 [0.905, 0.997]). There were no significant effects of the environment on behavioural conditions.
Our study utilises a large national sample of almost one million young people to confirm the importance of environmental determinants for mental health. It is possible that leverage points for improving the mental health of young people, and reducing the burden to the health system of mental health, can be sought in upstream environmental based interventions.

This study aims to provide an overview of the association between being in the custody of the chief executive of Oranga Tamariki (the child welfare agency of the New Zealand (NZ) government) and all-cause hospitalisation and mortality.
This was a national retrospective cohort study using linked administrative data from the Integrated Data Infrastructure. Data were obtained for all 0-17 year-olds living in NZ on 31 December 2013. In-care status was ascertained at this point. Outcomes of all-cause hospitalisation and all-cause mortality were assessed between 1 January 2014 and 31 December 2018. Adjusted models incorporated age, sex, ethnicity, level of socioeconomic deprivation and rural/urban status.
There were 4650 in-care children and 1 009 377 not-in-care children in NZ on 31 December 2013. Of those in care, 54% were male, 42% lived in the most deprived areas and 63% identified as Māori. Adjusted models showed that in-care children were 1.32 (95% CI 1.27-1.38) times more likely to be hospitalised than not-in-care children and 3.64 (95% CI 2.47-5.40) times more likely to die.
This cohort study highlights that the care and protection system prior to 2018 was not preventing children in its care from experiencing severe adverse outcomes. Overseas research has previously been relied on when making practice and policy decisions around child care and protection in NZ, so this research will provide valuable insight into best practice in an NZ context.

The combined oral contraceptive (COC) is the most commonly used hormonal contraceptive in Aotearoa New Zealand (Aotearoa/NZ). Currently there is limited data available on who uses COC in Aotearoa/NZ. The aims were to (i) define the population of reproductive-aged females in Aotearoa/NZ in 2018 and identify the rate of COC use among this group and (ii) describe the sociodemographic and geographic characteristics of the population of COC users compared to the general population of reproductive-aged females in 2018.
This whole-of-population cross-sectional study used the Integrated Data Infrastructure, a large research database managed by Statistics New Zealand. Females aged 16-50 years with complete sociodemographic and geographic information in 2018 from Aotearoa/NZ\'s estimated resident population were included. COC dispensing records to this cohort were identified from the national Pharmaceutical Collection. This paper reports descriptive counts of COC use and employs generalised linear regression with a binomial distribution and a log link to estimate adjusted risk ratios (aRR) of COC use for key sociodemographic and geographic subgroups.
Of 1 113 750 individuals in the study, 159 789 (14.3%) were dispensed as COC in 2018. European/other individuals were most likely to use COC (aRR: 2.72, 2.67-2.78), and Pacific Peoples were least likely (aRR: 0.56, 0.55-0.58) to use COC. Individuals residing in the most deprived quintile had less COC use than individuals in the least deprived quintile (aRR: 0.73, 0.72-0.74).
Our study is able to highlight significant disparities in use by ethnicity, area-level deprivation, and geographic factors.

UNASSIGNED: Sensationalist headlines and highly publicised criminal cases lead many in the public to believe that people with autism are more likely to engage in criminal behaviour. However, recent studies present an unresolved debate, and indicate this may not necessarily be the case. The aims of this study were to examine the prevalence of criminal justice system interactions among young adults with and without autism, and determine whether offence types differ between these groups. We tracked a national birth cohort until their 25th birthday, detecting criminal justice system interactions from age 17 onwards. Linked health and criminal justice system data were used to identify those with autism and detect interactions with the criminal justice system. We found that young people with autism interacted with the criminal justice system at lower rates compared to those without autism. However, there were considerable differences in the types of offences these young people were charged with. For example, among those charged with an offence, people with autism were more likely to be charged with a serious offence, punishable by 2 or more years in prison. We conclude that although young people with autism are not over-represented in the criminal justice system, disparities in offence types and incarceration rates among those charged with an offence suggest the importance of identification and appropriate response to autism within the criminal justice system.

New Zealand has few estimates of the prevalence autism spectrum disorder and no national registry or data set to identify and track cases. This hinders the ability to make informed, evidence-based decisions relating to autism spectrum disorder. In this study, we utilised linked health and non-health data to develop a method for identifying cases of autism spectrum disorder among children and young people in New Zealand. In addition, we examined rates of co-occurring mental health, neurodevelopmental and related conditions among this cohort and compared these to the general population. The method identified almost 10,000 children and young people with autism spectrum disorder in New Zealand. Co-occurring mental health or related problems were found in over 68% of this group (nearly seven times higher than the general population), and around half were identified with multiple co-occurring conditions. The most frequently identified conditions were intellectual disability, disruptive behaviours and emotional problems. We have developed a useful method for monitoring service and treatment-related trends, number and types of co-occurring conditions and examining social outcomes among individuals with autism spectrum disorder. While the method may underestimate the prevalence of autism spectrum disorder in New Zealand, it provides a significant step towards establishing a more comprehensive evidence base to inform autism spectrum disorder-related policy.

In a novel endeavour we aimed to develop a clinically relevant case identification method for use in research about the mental health of children and young people in New Zealand using the Integrated Data Infrastructure (IDI). The IDI is a linked individual-level database containing New Zealand government and survey microdata.
We drew on diagnostic and pharmaceutical information contained within five secondary care service use and medication dispensing datasets to identify probable cases of mental health and related problems. A systematic classification and refinement of codes, including restrictions by age, was undertaken to assign cases into 13 different mental health problem categories. This process was carried out by a panel of eight specialists covering a diverse range of mental health disciplines (a clinical psychologist, four child and adolescent psychiatrists and three academic researchers in child and adolescent mental health). The case identification method was applied to the New Zealand youth estimated resident population for the 2014/15 fiscal year.
Over 82,000 unique individuals aged 0-24 with at least one specified mental health or related problem were identified using the case identification method for the 2014/15 fiscal year. The most prevalent mental health problem subgroups were emotional problems (31,266 individuals), substance problems (16,314), and disruptive behaviours (13,758). Overall, the pharmaceutical collection was the largest source of case identification data (59,862).
This study demonstrates the value of utilising IDI data for mental health research. Although the method is yet to be fully validated, it moves beyond incidence rates based on single data sources, and provides directions for future use, including further linkage of data to the IDI.