Data Linkage Branch Research Articles

Overweight/obesity and other predictors of gestational diabetes among Aboriginal and non-Aboriginal women in Western Australia

This population-based study investigated the association of BMI and other predictors with gestational diabetes mellitus (GDM) among Australian Aboriginal and non-Aboriginal mothers. We conducted a state-wide retrospective cohort study that included all singleton births in Western Australia (n = 134,552) between 2012 and 2015 using population health datasets linked by the Western Australian Data Linkage Branch. Associations between GDM and its predictors were estimated as adjusted relative risks (aRRs) from multivariable generalised linear models. Adjusted ratio of relative risks (aRRRs) compared RRs in Aboriginal and non-Aboriginal mothers. Adjusted population attributable fractions estimated the contribution of overweight/obesity to GDM burden, and adjusted predicted probabilities for GDM were plotted against BMI levels. The following predictors had stronger associations with GDM in Aboriginal, compared to non-Aboriginal, mothers: maternal obesity (aRR [95% CI] 3.16 [2.54–3.93]; aRRR 1.57 [1.26–1.94]), previous LGA (aRR 1.70 [1.37–2.12]; aRRR 1.41 [1.13–1.76]) and previous macrosomia (birthweight ≥ 4 kg) (aRR 1.55 [1.24–1.94]; aRRR 1.53 [1.22–1.91]). 46.1% (95% CI: 36.6–54.1) of GDM cases in Aboriginal women (23.3% in non-Aboriginal mothers, 95% CI: 21.6–25.1) were attributed to overweight/obesity. Compared to non-Aboriginal mothers, adjusted GDM probabilities were higher at all BMI levels and showed greater increase with BMI. Overweight/obesity is a key driver of GDM among Aboriginal women. Association between BMI and GDM is stronger in Aboriginal, compared to non-Aboriginal, women especially at higher BMI.

Cooperation and Innovation in Data Linkage Creates A Linked, Multi-Sectoral Data Repository for Western Australia – The SIDR Project

IntroductionDuring 2019, the Western Australian (WA) government and Curtin University’s Centre for Data Linkage (CDL) created a large, de-identified researchable database – the Social Investment Data Resource (SIDR) – to support government in delivering targeted early interventions to young offenders and their families to reduce the likelihood of re-offending (the Target 120 program).
 Objectives and ApproachSIDR brings together administrative data from health, education, justice, child protection, disability and housing sectors. The linked, de-identified data provides an invaluable resource for actuarial assessment and social investment analytics to assess long-term costs and benefits of the Target 120 program. SIDR also provides an invaluable tool for academic research. SIDR adopted a distributed linkage model where linkage workload was shared between the Department of Health Data Linkage Branch who create and maintain the WA Data Linkage System (WADLS) and the CDL. Design elements of the model included a common spine (embedded into the infrastructure of both groups), methods for leveraging quality from WADLS, and inclusion of family relationships data from the WA Family Connections database. The linkage model within SIDR uses a combination of traditional and privacy-preserving record linkage (PPRL) methods. PPRL does not require release of personal identifiers; instead, data is irreversibly hashed prior to release for probabilistic linkage.
 ResultsThrough cooperation (distributed linkage) and innovation (a mix of traditional and PPRL linkage), the project has delivered a large, linked, cross-sectoral data resource for policymakers and researchers. Sharing of the linkage workload maximised the capacity and unique capabilities of each linkage unit. PPRL enabled ‘hard to get’ datasets from justice to be included. SIDR is being updated in 2020.
 Conclusion / ImplicationsSIDR provides a resource for whole-of-government policy development, service evaluation, academic research and social investment analytics for T120 and beyond. The SIDR linkage model has potential for adaptation and use elsewhere.

Identifying young Aboriginal and Torres Strait Islander children in linked administrative data: A comparison of methods

BackgroundIn the ongoing debate on optimum methods for identification of Indigenous people within linked administrative data, few studies have examined the impacts of method on population counts and outcomes in family-based linkage studies of Aboriginal children.ObjectiveTo quantify differences between three algorithms in ascertaining Aboriginal and Torres Strait Islander children in linked administrative data.MethodsLinked administrative health data for children born in Western Australia (WA) from 2000-2013, were used to examine the cohorts identified by three methods: A) the Indigenous Status Flag (ISF, derived by the WA Data Linkage Branch using a multistage-median approach) for the children alone; B) the ISF of the children, their parents and grandparents; and C) Indigenous status of the child, mother or father on either of the child’s perinatal records (Midwives or birth registration), to determine differing characteristics of each cohort.ResultsMethod B established a larger cohort (33,489) than Method C (33,306) and Method A (27,279), with all methods identifying a core group of 26,790 children (80-98%). Compared with children identified by Method A, additional children identified by Methods B or C, were from less-disadvantaged and more urban areas, and had better perinatal outcomes (e.g. lower proportions of small-for-gestational age, 10% vs 16%). Differences in demographics and health outcomes between Methods C and B were minimal.ConclusionsDemographic and perinatal health characteristics differ by Aboriginal identification method. Using perinatal records or the ISF of parents and grandparents (in addition to the ISF of the child) appear to be more inclusive methods for identifying young Indigenous children in administrative datasets.KeywordsAboriginal health, identification, data linkage, Indigenous, child, methodology

Population Data Centre Profile - The Western Australian Data Linkage Branch.

Established in 1995, the Western Australian Data Linkage Branch (DLB) is Australia’s longest running data linkage agency. The Western Australian Data Linkage System (WADLS) employs an enduring linkage model spanning over 60 data collections supported by internally developed and supported software and IT infrastructure. DLB has delivered, and continues to deliver, a range of significant data linkage innovations, many of which have been adopted elsewhere. A current restructure within the Western Australian Department of Health (which we will refer to as the Department of Health) will provide an improved funding model geared toward addressing issues with staff retention, capacity and customer service, as well as fostering improvements to data management, governance and availability. Research using linked data provided by DLB has been used in over 800 projects resulting in over 2350 publications and outcomes for policy development, service delivery and public health. Demand continues to grow for data linkage services and with the Department of Health’s bolstered commitment to resourcing, DLB looks forward to a future for data linkage in Western Australia that is sustainable, high quality, efficient, and safe.

Using data linkage innovation and collaboration to create a cross-sectoral data repository for Western Australia

Background/rationaleThe Western Australian (WA) government and the Centre for Data Linkage (CDL) at Curtin University are creating a large, de-identified researchable database – the Social Investment Data Resource (SIDR) – to support a key government initiative called Target 120 (T120). T120 delivers targeted early interventions to young offenders and their families to reduce the likelihood of re-offending.
 Main AimThe SIDR brings together de-identified data from across government to be used for actuarial assessment and social investment analytics to assess long-term costs and benefits of T120 interventions.
 MethodsSIDR adopts a distributed linkage model where linkage workload is shared between the Department of Health Data Linkage Branch who curate WA Data Linkage System (WADLS) and the CDL. Design elements of the model included a common spine (embedded into the infrastructure of both groups), methods for leveraging quality from WADLS, and inclusion of family relationships data from the WA Family Connections database. The linkage model uses a combination of traditional and privacy-preserving record linkage (PPRL) methods. PPRL does not require release of personal identifiers; instead, data is irreversibly hashed prior to release for probabilistic linkage.
 The resultant SIDR repository has been designed to be securely and strictly managed. Access is by authorised, approved users only.
 ResultsUse of a distributed linkage model, coupled with traditional and PPRL methods, is an innovative yet pragmatic way of delivering data linkage services to a large, cross-sectoral research project. PPRL methods enable inclusion of otherwise excluded datasets in the project. Sharing of workload harnesses linkage capacity and capabilities across the state. The SIDR includes health data, education records, justice, child protection, disability and housing data.
 ConclusionSIDR provides a resource for whole-of-government policy development, service evaluation, academic research and social investment analytics for T120 and beyond. The SIDR distributed linkage model has potential for adaptation and use elsewhere.

Incidence and Determinants of Mental Health Service Use After Bariatric Surgery

Obesity is associated with an increased prevalence of psychiatric disorders. The association of bariatric surgery with mental health outcomes is poorly understood. To investigate the association of bariatric surgery with the incidence of outpatient, emergency department (ED), and inpatient mental health service use. This statewide, mirror-image, longitudinal cohort study used data from Western Australian Department of Health Data Linkage Branch records from all patients undergoing index (ie, first) bariatric surgery in Western Australia over a 10-year period (January 2007-December 2016), with mean (SD) follow-up periods of 10.2 (2.9) years before and 5.2 (2.9) years after index bariatric surgery. The data analysis was performed between November 2018 and March 2019. Index bariatric surgery. The incidence and predictors for mental health presentations, deliberate self-harm, and suicide in association with the timing of bariatric surgery. A total of 24 766 patients underwent index bariatric surgery; of these, the mean (SD) age was 42.5 (11.7) years and 19 144 (77.3%) were women. Use of at least 1 mental health service occurred in 3976 patients (16.1%), with 1401 patients (35.2%) presenting only before surgery, 1025 (25.8%) presenting before and after surgery, and 1550 patients (39.0%) presenting only after surgery. There was an increase in psychiatric illness presentations after bariatric surgery (outpatient clinic attendance: incidence rate ratio [IRR], 2.3; 95% CI, 2.3-2.4; ED attendance: IRR, 3.0; 95% CI, 2.8-3.2; psychiatric hospitalization: IRR, 3.0; 95% CI, 2.8-3.1). There was also a 5-fold increase in deliberate self-harm presentations to an ED after surgery (IRR, 4.7; 95% CI, 3.8-5.7), with 25 of 261 postoperatives deaths (9.6%) due to suicide. Complications after bariatric surgery requiring further surgical intervention and a history of mental health service provision before surgery were the most important associations with subsequent mental health presentations after surgery. Deliberate self-harm and mental and behavioral disorders due to psychoactive substance use before bariatric surgery were the main associations with subsequent deliberate self-harm or suicide after surgery. We observed an increase in mental health service presentations after bariatric surgery, particularly among those who had prior psychiatric illnesses or developed surgical complications requiring further surgery. These findings caution the hypothesis that weight reduction by bariatric surgery will improve mental health in patients with obesity.

Fit for purpose - developing a software platform to support the modern challenges of data linkage in Western Australia

The Western Australia Data Linkage System (WADLS) is maintained and operated by the WA Data Linkage Branch (DLB) at the Western Australian Department of Health. DLB has pioneered a number of data linkage innovations, including the facilitation of genealogical research via the Family Connections system and streamlined data delivery via the Custodian Administered Research Extract Server. DLB’s latest innovation is a new data linkage system called “DLS3”, which improves DLB’s capability and capacity to handle the increasing volume and complexity of its routine operations. DLS3 was built entirely in-house and customised to meet the specific challenges that DLB has encountered throughout over twenty years of experience with a wide variety of linkages. This article describes the development and rollout of DLS3, including its design, architecture, benefits and limitations.

Profile of Children Who Died in the First 5 Years of Life in Western Australia, 1980‐2010

Background In Western Australia (WA), mortality rates among children aged <5 years decreased over time but remains highest among infants aged <1 year. Furthermore, mortality rates among Aboriginal and Torres Strait Islander (hereafter Aboriginal) children are double that of their non‐Aboriginal peers. We describe the profile of Aboriginal and non‐Aboriginal WA‐born children who died before their 5th birthday. Methods Using data extracted from core population health datasets and linked by the Data Linkage Branch of the Western Australia Department of Health, we identified deaths and associated demographic, hospitalisation and developmental anomaly data. Mortality rate ratios (RR) were calculated using EpiBasic. Results Of 786,539 liveborn children in 1980‐2010, there were 5531 deaths in children aged <5 years (mortality rate=7.0 per 1000 live births). Aboriginal children were 3.5 times (95% CI=3.3‐3.8) more likely to die before their 5th birthday than non‐Aboriginal children, with the most pronounced differences among those born at 37‐41 weeks gestation (RR=4.0, 95% CI=3.6‐4.4). Approximately 53.4% of all liveborn children were hospitalised at least once while 5.3% had at least 1 developmental anomaly. Mortality rates among all children who had both hospital and developmental anomaly records were at least 3 times higher than those with neither. Conclusions Childhood mortality risk varies by gestational age, developmental anomaly and history of hospitalisation. Excess mortality among Aboriginal children likely reflects a different profile of chronic conditions among these children and inequalities in access to services. Deeper investigations into pathways to early mortality can inform future interventions.

Chlamydia trachomatis and the risk of spontaneous preterm birth, babies who are born small for gestational age, and stillbirth: a population-based cohort study

Chlamydia trachomatis is one of the most commonly diagnosed sexually transmitted infections worldwide, but reports in the medical literature of an association between genital chlamydia infection and adverse obstetric outcomes are inconsistent. The Western Australia Data Linkage Branch created a cohort of women of reproductive age by linking records of birth registrations with the electoral roll for women in Western Australia who were born from 1974 to 1995. The cohort was then linked to both chlamydia testing records and the state perinatal registry for data on preterm births and other adverse obstetric outcomes. We determined associations between chlamydia testing, test positivity, and adverse obstetric outcomes using multivariate logistic regression analyses. From 2001 to 2012, 101 558 women aged 15 to 38 years had a singleton birth. Of these women, 3921 (3·9%) had a spontaneous preterm birth, 9762 (9·6% of 101 371 women with available data) had a baby who was small for gestational age, and 682 (0·7%) had a stillbirth. During their pregnancy, 21 267 (20·9%) of these women had at least one chlamydia test record, and 1365 (6·4%) of those tested were positive. Before pregnancy, 19 157 (18·9%) of these women were tested for chlamydia, of whom 1595 (8·3%) tested positive for chlamydia. Among all women with a test record, after adjusting for age, ethnicity, maternal smoking, and history of other infections, we found no significant association between a positive test for chlamydia and spontaneous preterm birth (adjusted odds ratio 1·08 [95% CI 0·91-1·28]; p=0·37), a baby who was small for gestational age (0·95 [0·85-1·07]; p=0·39), or stillbirth (0·93 [0·61-1·42]; p=0·74). A genital chlamydia infection that is diagnosed and, presumably, treated either during or before pregnancy does not substantially increase a woman's risk of having a spontaneous preterm birth, having a baby who is small for gestational age, or having a stillbirth. Australian National Health and Medical Research Council.

Assessing mental health outcomes for residents of supported accommodation services

ABSTRACT&#x0D; ObjectivesSupported accommodation services provide housing for people with a severe and persistent mental illness; people who are homeless, at risk of homelessness, in unsuitable accommodation, or residing for long periods in inpatient units. The aim of this research is to examine the extent to which supported accommodation impacts on levels and costs of hospitalisation, utilisation of community based clinical services and mental health outcomes of present and past residents.&#x0D; ApproachThe research will make use of demographic data from supported accommodation services and Western Australian (WA) linked data from existing health data collections by the Data Linkage Branch WA Health. The data linkage methodology used involves the linking and analysis of data between 1997 and 2013 from a diverse number of datasets (Hospital Morbidity data, Mental Health Ambulatory data, Emergency data, Mortality data and Hospital Cost data). The impact of supported accommodation on individuals was measured by tracking any changes in their service utilisation levels and associated hospital costs savings. This allowed us to determine the efficacy of supported accommodation services through time series and control group comparative analysis.&#x0D; ResultsPeople with severe or persistent mental illness who reside in supported accommodation services are more likely to maintain or improve their quality of life and mental health outcomes compared to those who have never entered supported accommodation. Individuals who utilised these services also experienced reduced hospitalizations after the service than before. Cost implications will also be discussed.&#x0D; Conclusions No significant research into the effectiveness of supported accommodation on mental health outcomes for individuals has been conducted in WA to date. Supported accommodation provides people with severe and persistent mental illness, along with their families, carers and supporters, more security and control over their lives, and improved access to appropriate supports and clinical services. This research will support these strategic directions by providing evidence about the effectiveness of supported accommodation options in terms of improving mental health outcomes for individuals.

Retinal detachment surgery in Western Australia (2000–2013): a whole-population study

AimsTo determine the background incidence rate of retinal detachment (RD) in Western Australia (WA) between 2000 and 2013, identify sociodemographic features associated with increased risk of incident RD and examine...

Quantifying maternal incarceration: a whole‐population linked data study of Western Australian children born 1985–2011

Objective:To measure the prevalence of children affected by maternal incarceration in Western Australia (WA). Methods:Using linked administrative data we identified all children born in WA between 1985 and 2011, whose biological mother was imprisoned during their childhood. Data was obtained through the WA Data Linkage Branch from the Department of Corrective Services, Midwives Notifications System and Birth Registrations data collections. Descriptive characteristics of the children (n=9,352) and their mothers (n=3,827) are reported. Prevalence was measured in two‐ways, the proportion of children ever affected in childhood and affected annually. Results:Childhood prevalence of maternal incarceration was 26‐times higher (95%CI 23.9–28.2) for Indigenous children born 1992–1996 with 18.8% Indigenous children and 0.7% non‐Indigenous children affected while aged 0–17 years. On average 1,544 children were affected each year across 2003–2011, at rates of 2,929 per 100,000 Indigenous children and 108 per 100,000 non‐Indigenous children. Conclusions:The findings present the first census of children affected by maternal incarceration within an Australian State and identify a large disparity between Indigenous and non‐Indigenous populations. Implications for public health:This study highlights the importance of formal consideration of children of women prisoners in the development of criminal justice policies and practices.

A Western dietary pattern is associated with poor academic performance in Australian adolescents.

The aim of this study was to investigate cross-sectional associations between dietary patterns and academic performance among 14-year-old adolescents. Study participants were from the Western Australian Pregnancy Cohort (Raine) Study. A food frequency questionnaire was administered when the adolescents were 14 years old, and from the dietary data, a ‘Healthy’ and a ‘Western’ dietary pattern were identified by factor analysis. The Western Australian Literacy and Numeracy Assessment (WALNA) results from grade nine (age 14) were linked to the Raine Study data by The Western Australian Data Linkage Branch. Associations between the dietary patterns and the WALNA (mathematics, reading and writing scores) were assessed using multivariate linear regression models adjusting for family and socioeconomic characteristics. Complete data on dietary patterns, academic performance and covariates were available for individuals across the different analyses as follows: n = 779 for mathematics, n = 741 for reading and n = 470 for writing. Following adjustment, significant negative associations between the ‘Western’ dietary pattern and test scores for mathematics (β = −13.14; 95% CI: −24.57; −1.76); p = 0.024) and reading (β = −19.16; 95% CI: −29.85; −8.47; p ≤ 0.001) were observed. A similar trend was found with respect to writing (β = −17.28; 95% CI: −35.74; 1.18; p = 0.066). ANOVA showed significant trends in estimated means of academic scores across quartiles for both the Western and Healthy patterns. Higher scores for the ‘Western’ dietary pattern are associated with poorer academic performance in adolescence.

The custodian administered research extract server: "improving the pipeline" in linked data delivery systems.

BackgroundAt Western Australia’s Data Linkage Branch (DLB) the extraction of linked data has become increasingly complex over the past decade and classical methods of data delivery are unsuited to the larger extractions which have become the norm. The Custodian Administered Research Extract Server (CARES) is a fast, accurate and predictable approach to linked data extraction.MethodsThe Data Linkage Branch (DLB) creates linkage keys within and between datasets. To comply with the separation principal, these keys are sent to applicable data collection agencies for extraction. Routing requests through multiple channels is inefficient and makes it hard to monitor work and predict delivery times. CARES was developed to address these shortcomings and involved ongoing consultation with the Custodians and staff of collections, plus challenges of hardware, programming, governance and security.ResultsThe introduction of CARES has reduced the workload burden of linked data extractions, while improving the efficiency, stability and predictability of turnaround times.ConclusionsAs the scope of a linkage system broadens, challenges in data delivery are inevitable. CARES overcomes multiple obstacles with no sacrifice to the integrity, confidentiality or security of data. CARES is a valuable component of linkage infrastructure that is operable at any scale and adaptable to many data environments.