BACKGROUND:Language development is critical for children's life chances. Promoting parent-child interactions is suggested as one mechanism to support language development in the early years. However, limited evidence exists for a causal effect of parent-child interactions on children's language development. METHODS:Data from the Language in Little Ones study, an Australian prospective birth cohort study (n = 296), was used to determine the sustained effect of parent-child interactions over time on children's language development at 36 and 48 months, measured using the Clinical Evaluation of Language Fundamentals Preschool-2 (CELF-P2) language assessment. Marginal structural models and inverse probability of treatment weights were used to allow observational data to emulate a randomised controlled trial by accounting for time-varying exposures and confounding. These results were then used to estimate the effect of several hypothetical scenarios where the exposure was fixed for the whole population at different levels (5th, 25th, 50th, 75th and 95th percentile) across the observed distribution of parent-child interactions. RESULTS:Findings supported a causal effect of parent-child interactions from 6 to 36 (or 48) months on children's language development at 36 and 48 months, in a population of children without language impairment. The counterfactual language score at 48 months increased from 97.21 (95% CI 96.86, 97.56) for the scenario fixed at the 5th percentile to 102.15 (95% CI 101.80, 102.50) at the 50th percentile and 111.41 (95% CI 111.06, 111.76) at the 95th percentile. CONCLUSIONS:Although the effects of parent-child interactions on later language were small they do offer one mechanism to support early language development. These findings are discussed within the context of existing interventions to highlight the value of investment into sustained, universal prevention efforts for supporting early language. WHAT THIS PAPER ADDS:What is already known on the subject Promoting parent-child interactions within the home environment has been previously suggested as one mechanism to support children's early language development. Nonetheless, there is a lack of causal evidence and long-term follow-up to support this claim. What this paper adds to the existing knowledge The effect of parent-child interactions throughout the early years on children's language development is explored using causal inference methodology within an Australian prospective birth cohort study. Findings show a small causal effect of increasing parent-child interactions on children's language development at 36 and 48 months, after controlling for time-varying exposures and confounders. What are the potential or actual clinical implications of this work? This highlights the value of sustained, universal early intervention, which encourages back-and-forth parent-child interactions, as early as possible. Practitioners who work with parents and carers in the first year of a child's life should promote the importance of talking and interacting with their child to improve later language outcomes.

BACKGROUND AND AIMS:Smoking cessation during pregnancy results in short- and long-term health benefits for the mother and infant. Despite public health policies and initiatives to reduce smoking, smoking in pregnancy remains unacceptably high in Australia, particularly among populations of high disadvantage. Internationally, the use of financial incentives has shown some promise in assisting pregnant women to quit smoking, but more research is needed in different contexts. This study aims to determine the efficacy, cost-effectiveness and acceptability of the use of financial incentives in Australia. DESIGN:2-arm parallel-group randomised controlled trial. SETTING:Australian antenatal care setting. PARTICIPANTS:Pregnant women who smoke. INTERVENTION:Women randomised to the intervention group will receive financial incentives of increasing value at three time points throughout their pregnancy (4 and 12 weeks from the first antenatal visit and 37 weeks gestation) upon confirmation of smoking abstinence. MEASUREMENTS:The primary comparison outcome is a composite binary measure of abstinence at three time points during pregnancy (4, 12 and 37 weeks). Smoking abstinence will be determined by a carbon monoxide breath analysis reading of ≤3 ppm. The primary statistical analysis is estimation of the absolute difference in the prevalence of abstinence at all three time points based on the intention-to-treat groups. A cost-effectiveness analysis will be undertaken to quantify the social returns of the intervention. A qualitative process evaluation will also be conducted to determine fidelity, contextual factors and the acceptability of the intervention to pregnant women and healthcare workers. COMMENTS:This study will be the first Australian trial of financial incentives in reducing smoking in pregnancy. The findings will provide evidence on the acceptability, effectiveness and cost-effectiveness of financial incentives to reduce smoking in pregnancy in Australia.

This was made longer in response to request from reviewers. If a longer abstract cannot be accommodated, a shorter abstract is pasted here: Children who have 'early contact' with youth justice (YJ) are a group of significant policy interest. Understanding circumstances which precede or co-occur with YJ contact can support the development of preventive investments and inform debates about systemic reform, such as 'raise the age'. Using whole-of-population administrative data from the SA Better Evidence Better Outcomes Linked Data (BEBOLD) platform, we examine differences between children who have early (i.e. between the ages of 10 and 13 years) versus late (i.e. at age 14 or older) YJ contact, relative to the general population. Children born 1991-2022 were followed from birth to age 18 (N = 249,995). Compared to the late-contact group, children with early contact experienced more serious YJ contact (91% versus 59% experienced custody); were more disadvantaged at birth (e.g. 66% versus 45% born into jobless families); had more serious child protection contact by age 10 (26% versus 12% experienced out-of-home care); and experienced mental health-related hospitalisations from ages 12-18 (43% versus 34%). Relative to the general population, both groups were characterised by significant social and economic disadvantage, child protection contact and mental health challenges. The need for investment in early prevention to divert children from the justice system is clear.

Background Preterm birth (PTB) is a leading cause of child morbidity and mortality. Evidence suggests an increased risk with both maternal underweight and obesity, with some studies suggesting underweight might be a greater factor in spontaneous PTB (SPTB) and that the relationship might vary by parity. Previous studies have largely explored established body mass index (BMI) categories. Our aim was to compare associations of maternal pre-pregnancy BMI with any PTB, SPTB and medically indicated PTB (MPTB) among nulliparous and parous women across populations with differing characteristics, and to identify the optimal BMI with lowest risk for these outcomes. Methods We used three UK datasets, two USA datasets and one each from South Australia, Norway and Denmark, together including just under 29 million pregnancies resulting in a live birth or stillbirth after 24 completed weeks gestation. Fractional polynomial multivariable logistic regression was used to examine the relationship of maternal BMI with any PTB, SPTB and MPTB, among nulliparous and parous women separately. The results were combined using a random effects meta-analysis. The estimated BMI at which risk was lowest was calculated via differentiation and a 95% confidence interval (CI) obtained using bootstrapping. Results We found non-linear associations between BMI and all three outcomes, across all datasets. The adjusted risk of any PTB and MPTB was elevated at both low and high BMIs, whereas the risk of SPTB was increased at lower levels of BMI but remained low or increased only slightly with higher BMI. In the meta-analysed data, the lowest risk of any PTB was at a BMI of 22.5 kg/m 2 (95% CI 21.5, 23.5) among nulliparous women and 25.9 kg/m 2 (95% CI 24.1, 31.7) among multiparous women, with values of 20.4 kg/m 2 (20.0, 21.1) and 22.2 kg/m 2 (21.1, 24.3), respectively, for MPTB; for SPTB, the risk remained roughly largely constant above a BMI of around 25–30 kg/m 2 regardless of parity. Conclusions Consistency of findings across different populations, despite differences between them in terms of the time period covered, the BMI distribution, missing data and control for key confounders, suggests that severe under- and overweight may play a role in PTB risk.

In Australia, as elsewhere, there is consensus that new and more effective ways of responding to young people who commit crimes need to be identified and, when available, implemented and evaluated. In this paper we review youth justice legislation across each Australian jurisdiction and consider how it provides the mandate for service delivery. We contextualise this with an account of historical variations in how the seemingly competing goals of welfare and justice have been balanced. This is followed by an overview of contemporary understandings of child development and human rights which are increasingly recognised as both relevant and important to the way in which the community works with justice-involved children and young people. The analysis illustrates how youth justice agencies are still expected to achieve multiple and, at times, conflicting legislated objectives which results in a lack of coherence in policy and practice. This serves only to limit effectiveness. We conclude that legislative reform will be necessary to realise any new vision for youth justice, especially if one of the overarching purposes is to protect vulnerable children.

IssuesAlthough maternal substance use is a known risk factor for child maltreatment, evidence on the scale of substance use is needed to inform prevention responses. This systematic review synthesised prevalence estimates of maternal substance use during pregnancy and early life among children at risk of maltreatment. Ovid, Pubmed, CINAHL, PsychInfo and ProQuest databases were searched. We included observational studies that sampled children at risk of maltreatment in high-income countries and reported information on maternal substance use during pregnancy and/or the child's first year of life. We extracted study characteristics and data to calculate prevalence, assessed risk of bias and conducted a narrative synthesis; there were insufficient comparable populations or outcomes to quantitatively synthesise results.Key FindingsThirty five of 14,084 titles were included. Fifteen studies had adequately sized and representative samples to estimate prevalence. Maternal substance use prevalence ranged from 2.4% to 40.6%. Maternal substance use was highest among infants referred to child protection at birth (40.6%) and children in out-of-home care (10.4% to 37.2%). Prevalence was higher when studies defined substance use more broadly and when maternal substance use was ascertained from both child and mother records.ImplicationsSupportive, coordinated responses to maternal substance use are needed from health and child protection services, spanning alcohol and other drug treatment, antenatal and postnatal care.ConclusionsPrenatal and early life maternal substance use is common among child maltreatment populations, particularly among younger children and those with more serious maltreatment.

Objective Youth criminal justice systems are under growing pressure to reduce re-offending behavior and to support young people’s health and developmental needs. This systematic review and meta-analysis sought to synthesise evidence for 2 prominent community-based interventions for delinquent and antisocial behavior, namely, multisystemic therapy (MST) and functional family therapy (FFT). Method We searched Medline, PsycInfo, Scopus, Web of Science, and Social Services Abstracts for randomized controlled trials (RCTs) and quasi-experimental studies evaluating MST/FFT. Included studies involved participants aged under 18 years; included interventions targeted delinquent/antisocial behavior, but not maltreatment. We estimated effect sizes for 6 primary outcomes, synthesising RCTs comparing MST/FFT to usual care using correlated hierarchical effects meta-analysis. We assessed risk of bias and evidence strength using best-practice tools. Given the additional resources needed to implement MST/FFT, we rated evidence strength against a minimum clinically important difference rather than a null effect. This study is registered with PROSPERO, CRD42021279736. Results We included 35 studies for MST (16 RCTs meta-analyzed comprising 4,095 participants, 26% female) and 19 studies for FFT (7 RCTs meta-analyzed comprising 1,471 participants, 22% female). MST had a likely clinically important effect on time in out-of-home care, but no clinically important effects on other primary outcomes (delinquency, new offenses/convictions, placement in out-of-home care, substance use), with low-to-moderate evidence strength. FFT demonstrated possible clinically important effects for the number of new offenses/convictions, time in out-of-home care, and substance use, but evidence strength was low. Conclusion Contrary to reports in some evidence clearinghouses indicating that MST/FFT are supported by the highest level of evidence strength, there is limited evidence that these interventions are superior to usual care in reducing delinquent and antisocial behavior in adolescence. These findings should be viewed in the context of important methodological differences with prior reviews, including the rating of evidence strength against a minimum clinically important difference. Study preregistration information The effect of Multi-Systemic Therapy and Functional Family Therapy in addressing child and adolescent delinquent and/or antisocial behavior and childhood maltreatment; https://www.crd.york.ac.uk/; 279736.

ObjectiveTo illustrate how whole-population linked data can be used to understand a system perspective of client complexity, and build robust evidence of Family by Family program impact. MethodsFamily by Family program (the program) participant data were linked into the Better Evidence Better Outcomes Linked Data (BEBOLD) Platform. BEBOLD is a whole-of-population linked de-identified administrative data platform for all South Australian children born 1991 onwards (n~500,000), as well as their parents including data spanning health, education, and social services. We descriptively analysed parental child protection history, emergency department presentations, hospitalisations, homelessness and justice system contact in the 24 months prior to and post program commencement. We emulate a trial using the ‘target trial’ causal inference framework to evaluate the program effect on a range of child outcomes using targeted maximum likelihood with a set of over 20 confounders. Results There were 361 families and 841 children in the program included in analysis. Selected results follow: Prior to the program, 35.8% of children were in a family where at least one parent had their own child protection history and 8% had a parent who experienced out-of-home care. Nearly 40% of children had at least one parent with a mental health related emergency department and/or hospitalisation, while 22% of children were in a family with specialist homelessness service contact. Program impact results will be presented at the conference. ConclusionThis research-practice partnership illustrates how bringing together program and linked-administrative data generates new evidence about client complexity and program impact.

Abstract Objectives: To estimate the prevalence of maternal substance use during the first 1000 days of children's lives, to inform planning and resourcing of antenatal screening and substance use in pregnancy services, alongside antenatal and postnatal health, parenting and social support services for pregnant women/new mothers and their babies. Method: This whole-population cohort was assembled from birth registration, perinatal, and hospital data for children born 2008-2017, and their mothers, using data linked for the New South Wales (NSW) Child E-Cohort Project. The primary outcome was maternal substance use and treatment recorded in six health, death, and child protection data sources from the child's conception to age 2-years (the first 1000 days), including illicit substances, alcohol, opioid-agonist treatment, and misuse of psychoactive medicines or substances. Results: Of 970,470 children born to 625,856 mothers, 3.4% (N=32,647) had ≥1 maternal substance use records in the first 1000 days, including alcohol use (N=13,647; 1.4%) and other drug use (N=23,485; 2.4%). Maternal substance use was recorded during the pregnancy period for 1.2% of children, and from 28-1000 days post-birth for 2.4% of children. Outcome ascertainment was highest from child protection records (N=26,045), followed by mother's (N=12,956) then children's hospital records (N=3,826). Child protection records more than doubled the prevalence from health and death records alone (1.4%). Social and health disadvantage was more common among children with maternal substance use. Conclusion: During the first 1000 days of life, 3.4% of NSW children had ≥1 maternal substance use record in health, child protection and death data sources. Child protection data enhances public health intelligence on the burden of maternal substance use among whole-populations of children. Near universal health system contact during pregnancy and birth is an opportunity to initiate early support for maternal substance use and co-occurring health and social disadvantage, to promote child health and development. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Madeleine Powell was supported by an Australian Government Research Training Program (RTP) Scholarship via the University of New South Wales (UNSW), Sydney, Australia, and a Higher Degree Research scholarship from the National Drug and Alcohol Research Centre (NDARC), UNSW. This work was supported by an NHMRC Clinical Trials and Cohort Studies grant (1187489) awarded to K Falster, R Pilkington, and J Lynch. R Pilkington and Tasnia Ahmed were supported by funds from the NHMRC Clinical Trials and Cohort Studies grant. Rhiannon Pilkington and Tasnia Ahmed were supported by an Australian National Health and Medical Research Council (NHMRC) Clinical Trials and Cohort Studies grant (#1187489). Alys Havard is supported by an NHMRC Ideas grant (#2010778) and the National Drug and Alcohol Research Centre, which is supported by funding from the Australian Government Department of Health under the Drug and Alcohol Program. The other authors received no additional funding. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval: This study was approved by the NSW Population and Health Services Research Ethics Committee (2020/ETH01265), the University of NSW HREC (2020/ETH01265), the Aboriginal Health and Medical Research Council (AH&MRC) of NSW Ethics Committee (1688/20), the NSW Corrective Services Ethics Committee (D20/0886760). The CHeReL operate under strict data security protocols and implements high level physical security measures. Their security protocols are in accordance with the Australian Government Protective Security Policy Framework, the Population Health Research Network Information Governance Framework, and the NHMRC Code for Responsible Conduct of Research. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data availability statement: No data are available because Australian privacy laws prohibit us from making the individual-level de-identified data publicly available. The data used for this study were provided by several Australian State and Commonwealth government agencies under agreements with the researchers led by KF (in NSW) and JWL (in SA), the NSW Centre for Health Record Linkage (CHeReL) and SANT Datalink, following approval from multiple ethics committees and data custodians. Data are only able to be accessed by researchers who are approved users by the relevant ethics committees and data custodians. Data can be accessed through an application and approval process administered by the independent data linkage authorities, NSW CHeReL or SANT Datalink.

Objective We describe aspects of social disadvantage in the northern Adelaide region, demonstrate how living with disadvantage impacts health outcomes to understand how the local health network can better serve this disadvantaged community. Design Using large scale, population-based data from the 2021 census we captured a snapshot of the disadvantage and health status of the community within the northern Adelaide region compared to the central and southern regions of Adelaide and other Australian capital cities. Results Northern Adelaide is a region of greater relative disadvantage, as shown by both the low Index of Relative Socio-Economic Disadvantage score (945) compared to the national average (1000) and scores above the national average for the central and southern Adelaide regions. Social determinants that contribute to this relative disadvantage include the proportion of people with no or limited education (26%) and those living on constrained income sources (e.g. unemployment benefits / aged pension, 10% and 72%, respectively). The northern Adelaide region has higher burdens of long-term health conditions including but not limited to diabetes, heart disease, kidney disease and lung diseases. The comparatively high prevalence of obesity (37%) for people in the north of Adelaide were associated with low numbers of people with adequate fruit intake (48%) and the higher proportion of people who currently smoke (16%) and who undertake low or no levels of exercise (73%). Conclusions Social disadvantage in the northern Adelaide region is associated with poorer health outcomes and higher levels of health risk behaviour compared to the less disadvantaged central and southern regions of Adelaide. Adapting health care to recognise this association may help improve the health of people living with disadvantage. Summary box ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: We analysed data from the Australian Bureau of Statistics (ABS), using the Social Health Atlas of Australia: 2021 Census and data by population health areas (PHA), updated throughout 2023. This data is available via the PHIDU website. https://phidu.torrens.edu.au I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes We analysed data from the Australian Bureau of Statistics (ABS), using the Social Health Atlas of Australia: 2021 Census and data by population health areas (PHA), updated throughout 2023. This data is publicly available via https://phidu.torrens.edu.au * ### List of Abbreviations ASR : Age-standardised rate CALHN : Central Adelaide local health network LGA : local government area LHN : local health network NALHN : Northern Adelaide local health network PHA : Public Health Area SALHN : Southern Adelaide local health network

OBJECTIVES:To investigate the number of mental health-related hospitalisations of adolescents (12-17 years) in South Australia by level of contact with the child protection system (0-11 years). STUDY DESIGN:Whole-of-population descriptive study; analysis of de-identified linked administrative data from the Better Evidence Better Outcomes Linked Data (BEBOLD) platform. SETTING, PARTICIPANTS:Adolescents born in South Australia, 1991-1999; linked SA Department for Child Protection, Admitted Patient Care (SA Health), and South Australian Perinatal Statistics collection (SA Department for Health and Wellbeing) data. MAIN OUTCOME MEASURES:Proportion of adolescents (12-17 years) hospitalised with mental health-related diagnoses; proportion of mental health-related hospitalisations of adolescents, by level of child protection contact (0-11 years) (no contact, notification but not screened in, screened-in notification but not investigated, investigation but not substantiated, substantiation, and out-of-home care). RESULTS:Of 175 115 adolescents born during 1991-1999, 5646 (3.2%) had been hospitalised with mental health conditions, and 27 203 (15.5%) had histories of contact with child protection services. The proportion of adolescents admitted to hospital with mental health-related diagnoses increased with the level of prior child protection contact, from 3366 of 147 912 adolescents with no contact (2.3%), to 398 of 6645 with notifications (6.0%), to 209 of 1191 who had been placed in out-of-home care (17.5%). Contact with child protection services was recorded for 2280 of 5646 adolescents admitted to hospital with mental health-related diagnoses (40.4%); 4477 of 10 633 mental health-related hospitalisations (44.9%) were of adolescents with histories of child protection services contact, including 1285 hospitalisations (12.1%) of adolescents for whom substantiated maltreatment (but not out-of-home care) was recorded, and 568 hospitalisations (5.3%) of adolescents who had been placed in out-of-home care. CONCLUSION:About 45% of mental health-related hospitalisations of 12-17-year-old adolescents were of people who had had contact with child protection services by the age of 11 years, although only 15.5% of all adolescents had histories of child protection contact. The trauma associated with a history of child protection can have longer term sequelae, and this should be considered when adolescents are hospitalised with mental health conditions.

ObjectiveQuantify the scale and type of maternal substance use from conception to the child’s second birthday (First 1000 days) to inform screening and support services that may reduce associated harm or risk for children. ApproachWe used mother and child records from whole-population health, death, and child protection datasets to ascertain maternal substance use during the First 1000 days for children born in NSW, Australia, from 2008-2017. The primary outcome - maternal substance use - included use of illicit substances, alcohol, opioid-agonist treatment, organic compounds, solvents, and misuse of prescription medicines. ICD-10 and SNOMED-CT diagnosis codes were used. ResultsThe birth cohort included 970,470 children and 625,856 mothers. 32,000 children (3.4%) had a record of maternal substance use during the First 1000 days of life, including 13,647 (1.4%) with alcohol and 23,485 (2.4%) other drug use. Ascertainment was highest from child protection records (26,045 children), followed by mother’s (12,956 children) then children’s hospital records (3,826 children). 18,672 (1.9%) children had a record of carer substance use only in child protection records. Combining data increased the prevalence estimates; adding child protection records increased the prevalence estimate to 3.4%, compared with 1.2% in health and death records alone. ConclusionMore than 3 in every 100 Australian children had a record of maternal substance use in administrative data during the First 1000 days of life in this decade-long study. In addition to health and death data, child protection data offers public health insights into the scale of maternal substance use among whole-population cohorts of children.

Purpose (the aim of the study): Despite the growing burden of hip osteoarthritis (HOA), primary prevention methods are slowly emerging. Early identification of HOA is crucial in enhancing our understanding of HOA development and treatment options. Several hip morphology risk factors play a role during the development of radiographic HOA (RHOA), but the exact contribution to RHOA risk in a broad population remains unclear. By combining individual participant data (IPD) of various studies while considering study heterogeneity, novel modeling techniques could be explored to work towards individualized prediction models.

Synergy analysis of HRI activation ex vivo

BACKGROUND:Populations willing to participate in randomized trials may not correspond well to policy-relevant target populations. Evidence of effectiveness that is complementary to randomized trials may be obtained by combining the 'target trial' causal inference framework with whole-of-population linked administrative data. METHODS:We demonstrate this approach in an evaluation of the South Australian Family Home Visiting Program, a nurse home visiting programme targeting socially disadvantaged families. Using de-identified data from 2004-10 in the ethics-approved Better Evidence Better Outcomes Linked Data (BEBOLD) platform, we characterized the policy-relevant population and emulated a trial evaluating effects on child developmental vulnerability at 5 years (n = 4160) and academic achievement at 9 years (n = 6370). Linkage to seven health, welfare and education data sources allowed adjustment for 29 confounders using Targeted Maximum Likelihood Estimation (TMLE) with SuperLearner. Sensitivity analyses assessed robustness to analytical choices. RESULTS:We demonstrated how the target trial framework may be used with linked administrative data to generate evidence for an intervention as it is delivered in practice in the community in the policy-relevant target population, and considering effects on outcomes years down the track. The target trial lens also aided in understanding and limiting the increased measurement, confounding and selection bias risks arising with such data. Substantively, we did not find robust evidence of a meaningful beneficial intervention effect. CONCLUSIONS:This approach could be a valuable avenue for generating high-quality, policy-relevant evidence that is complementary to trials, particularly when the target populations are multiply disadvantaged and less likely to participate in trials.

Objectives To examine the burden of mental health-related hospitalisations among adolescents by levels of previous child protection contact. Design, setting and participants Whole-of-population study of children born in South Australia, 1991-1999 (n=175,115), using de-identified linked administrative data from the Better Evidence Better Outcomes Linked Data (BEBOLD) platform. Main outcome measures Adolescents: proportion of adolescents aged 12-17 years with mental health hospitalisations; Hospitalisations: proportion of all adolescent mental health hospitalisations according to the level of child protection contact from 0-11 years. Results Overall, 15.5% (27,203/175,115 children) of adolescents had a history of child protection contact between ages 0-11 years, and 3.2% (5,646/175,115; 95% CI, 3.1 – 3.3) had a mental health-related hospitalisation between ages 12-17 years. Of the 10,633 mental health-related hospitalisations, 44.9% (95% CI, 44.0 – 45.9) were among adolescents with previous child protection contact even though they comprised only 15.5% of the study population. Of 5,646 adolescents with at least one mental health-related hospitalisation, 40.4% (95% CI, 39.1 – 41.7) had previous child protection contact. Among the population who experienced out-of-home care, 17.5% (209/1,191; 95% CI, 15.5 – 19.8) had experienced a mental health-related hospitalisation during adolescence, compared to 2.3% (3,366/147,912; 95% CI, 2.2 – 2.4) of adolescents with no prior child protection contact. Conclusion Almost 45% of mental health hospitalisations for 12-17-year-olds occurred among children who had child protection contact, despite that group comprising only 15.5% of the study population. Potential trauma sequelae associated with child protection history is important to consider in the response to adolescents hospitalised due to mental health challenges. The known Adolescent mental health is an important public health issue and those in child protection are at higher risk of experiencing mental health challenges. The new We have quantified the burden of adolescent mental health hospitalisations attributable to the population with prior child protection system contact. For adolescents aged 12-17 years, those with a child protection history accounted for 44.9% of all adolescent mental health hospitalisations. The implications Potential trauma sequelae associated with child protection history are important to consider in the response to adolescents hospitalised due to mental health challenges. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Prof Lynch was awarded a National Health and Medical Research Council (NHMRC) Australia Fellowship (award No. 570120); and NHMRC Centre of Research Excellence (award No. 1099422). Prof Lynch and Assoc Prof Chittleborough were awarded an NHMRC Partnership Project Grant (grant No. 1056888). Dr Pilkington and Ms Montgomerie were supported by funds from the NHMRC Centre for Research Excellence. Dr Malvaso is supported by an Australian Research Council Discovery Early Career Researcher Award (DE200100679). Ms Procter was supported by funds from the Westpac Scholars Trust. Ms Judd was supported by funds from Healthy Development Adelaide. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval was granted by the South Australian Department of Health Human Research Ethics Committee (2022/HRE00137), the University of Adelaide Human Research Ethics Committee (H-185-2011), and the Aboriginal Health Research Ethics Committee (REC2411/9/14). Approval to use these data was also provided by the custodians of each data source. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data analysed in the present study are not available.

Understanding what works to prevent and reduce youth crime often relies on randomised controlled trials (RCTs) to provide insights into intervention effectiveness. However, there are several challenges to conducting high-quality RCTs that may be more pronounced in this field due to the complex circumstances and background characteristics of justice populations. The RCT evidence base for Multi-Systemic Therapy (MST) is used as an example to illustrate barriers to understanding what works. It is apparent many effects of MST seen in the United States are not replicated in other contexts such as the UK, where there is a stronger "usual care" welfare system. This highlights the importance of considering local context and population needs in service planning. We discuss a complementary approach to evidence generation based on quasi-experimental methods that leverage and build on administrative linked data platforms. The increasing availability of administrative data is an opportunity to improve the quality of the evidence base we rely on to design, deliver, and evaluate services seeking to prevent youth crime. Without a strategically designed and appropriately funded system-wide intelligent information infrastructure, we will be limited in our ability to measure the success of investments to improve justice outcomes for young people in Australia.

Objective: Screen time guidelines recommend no screens under two years due to the potential negative impacts on development. While current reports suggest many children exceed this, research relies on parent reports of their children's screen exposure. We objectively assess screen exposure during the first two years and how it differs by maternal education and gender.Methods: This Australian prospective cohort study used speech recognition technology to understand young children's screen exposure over an average day. Data collection occurred every six months when children were 6, 12, 18 and, 24 months old (n = 207). The technology provided automated counts of children's exposure to electronic noise. Audio segments were then coded as screen exposure. Prevalence of screen exposure was quantified, and differences between demographics examined.Results: At six months, children were exposed to an average of 1hr, 16 min (SD = 1hr, 36 min) of screens per day, increasing to an average of 2 h, 28 min (SD = 2 h, 4 min) by 24-months. Some children at six months were exposed to more than 3 h of screen time per day. Inequalities in exposure were evident as early as six months. Children from higher educated families were exposed to 1hr,43 min fewer screens per day, 95%CI (-2hr, 13 min,-1hr, 11 min) compared to lower educated households, with this difference remaining consistent as children age. Girls were exposed to an additional 12 min of screens 95%CI (-20 min, 44 min) per day compared to boys at six months, but this difference reduced to only 5 min by 24-months.Conclusion: Using an objective measure of screen exposure, many families exceed screen time guidelines, the extent increasing with child's age. Furthermore, substantial differences between maternal education groups emerge as young as six months old. This highlights the need for education and supports for parents around screen use in the early years, balanced within the realities of modern life.