Population-based linkage of health records in Western Australia: development of a health services research linked database

Complexity in disease management: A linked data analysis of multimorbidity in Aboriginal and non-Aboriginal patients hospitalised with atherothrombotic disease in Western Australia

BACKGROUND

Hospitalisation for atherothrombotic disease (ATD) is expected to rise in coming decades. However, increasingly, associated comorbidities impose challenges in managing patients and deciding appropriate secondary prevention. We investigated the prevalence and pattern of multimorbidity (presence of two or more chronic conditions) in Aboriginal and non-Aboriginal Western Australian residents with ATDs.

METHODS AND FINDINGS

We used population-based de-identified linked administrative health data from 1 January 2000 to 30 June 2014 to identify a cohort of patients aged 25-59 years admitted to Western Australian hospitals with a discharge diagnosis of ATD. The prevalence of common chronic diseases in these patients was estimated and the patterns of comorbidities and multimorbidities empirically explored using two different approaches: identification of the most commonly occurring pairs and triplets of comorbid diseases, and through latent class analysis (LCA). Half of the cohort had multimorbidity, although this was much higher in Aboriginal people (Aboriginal: 79.2% vs. non-Aboriginal: 39.3%). Only a quarter were without any documented comorbidities. Hypertension, diabetes, alcohol abuse disorders and acid peptic diseases were the leading comorbidities in the major comorbid combinations across both Aboriginal and non-Aboriginal cohorts. The LCA identified four and six distinct clinically meaningful classes of multimorbidity for Aboriginal and non-Aboriginal patients, respectively. Out of the six groups in non-Aboriginal patients, four were similar to the groups identified in Aboriginal patients. The largest proportion of patients (33% in Aboriginal and 66% in non-Aboriginal) was assigned to the "minimally diseased" (or relatively healthy) group, with most patients having less than two conditions. Other groups showed variability in degree and pattern of multimorbidity.

CONCLUSION

Multimorbidity is common in ATD patients and the comorbidities tend to interact and cluster together. Physicians need to consider these in their clinical practice. Different treatment and secondary prevention strategies are likely to be useful for management in these cluster groups.

The relationship between intensification of blood glucose-lowering therapies, health status and quality of life in type 2 diabetes: The Fremantle Diabetes Study Phase II

AIMS

To determine whether therapeutic intensification in type 2 diabetes influences health status and quality of life (QoL).

METHODS

We studied 930 participants in the longitudinal observational Fremantle Diabetes Study Phase II (mean age 65.3 years, 53.8% males, median diabetes duration 8.0 years) with valid data from baseline assessment and two biennial reviews (4 years of follow-up) between 2008 and 2015. The main outcome measures were the Short Form-12 version 2 physical and mental health composite scores (PCS, MCS) and the average weighted impact (AWI) score from the Audit of Diabetes Dependent QoL.

RESULTS

There were reductions in PCS at Year 4 compared with baseline and Year 2 in patients on stable diet-based management (n = 160), oral glucose-lowering medication (OGLM; n = 387), and insulin with/without OGLM (n = 168; P < 0.05), but no statistically significant temporal changes in MCS/AWI. Insulin-treated patients had the lowest PCS, MCS and AWI compared to the other two subgroups at each time-point (P ≤ 0.012). In participants initiating OGLM (n = 84) or insulin (n = 85), there were no differences in PCS, MCS or AWI at the biennial assessments either side of these therapeutic changes (P ≥ 0.08).

CONCLUSIONS

These real-life data show that treatment intensification, including insulin initiation, does not impact adversely on patient well-being in community-based type 2 diabetes. Since insulin use at entry was associated with longer diabetes duration, worse glycaemic control, and a greater risk of chronic complications, the burden of disease rather than treatment modality appears the primary determinant of health status and QoL.

Trends in age- and sex-specific prevalence and incidence of cardiovascular disease in Western Australia

Background Temporal trends in incidence and mortality of cardiovascular disease (CVD) have been well described, with recent data suggesting declining improvements in those aged under 55 years. However, little is known about the combined impact of incidence and mortality trends on disease prevalence, an important indicator of disease burden and cost. We analysed changes in age-specific and age-standardised temporal trends in prevalence and incidence of CVD subtypes. Methods Annual prevalence and incidence rates of coronary heart disease, cerebrovascular disease and peripheral arterial disease for the Western Australian population for 1995-2010 were calculated using data from the Western Australian Data Linkage System. Joinpoint regression analyses were used to identify joinpoints in trends in age-specific and age-standardised annual prevalence and incidence rates for each CVD subtype. Results Between 1995 and 2010, age- and sex-specific incidence and prevalence of the CVD subtypes generally decreased among middle-aged and older adults, but were stable or increased among younger adults. In < 55 year olds, increases in incidence tended to occur from 2003, while increases in prevalence were from 2007/2008. Declines in age-standardised incidence were greater than those in crude incidence, with changes in population structure having a greater impact among men than women. Conclusions The majority of CVDs occurs in older adults. Our findings of generally worsening trends in prevalence in younger adults across most CVD subtypes were in contrast to generally declining trends in older age groups. These data highlight the importance of monitoring prevalence and incidence, particularly in younger adults.

Cultural and linguistic diversity increases the likelihood of compulsory community treatment

BACKGROUND

People from culturally and linguistically diverse (CALD) backgrounds are over-represented in compulsory admissions to hospital but little is known about whether this also applies to community treatment orders (CTOs).

AIMS

We investigated any differences between Australian- and foreign-born patients in the likelihood of CTO placement using state-wide databases from Western Australia.

METHODS

Cases and controls from administrative health data were matched on age, sex, diagnosis and time of hospital discharge (the index date). Logistic regression was then used to identify potential predictors of a CTO. We also assessed if any differences in CTO placement between Australian- and foreign-born patients had effects on bed-days or community contacts in the subsequent year.

RESULTS

We identified 2958 CTO cases and controls from November 1997 to December 2008 (total n=5916). Of these, 74% had schizophrenia or other non-affective psychoses. Patients who were born in New Zealand, the United Kingdom or Ireland had very similar rates of CTO placement compared to those who were Australian-born. By contrast, there was a gradient of increasing risk of CTO placement for people born in Continental Europe (OR_adj=1.36; 95% CI=1.07-1.71, p=0.01) and then the Rest of the World (OR_adj=1.61; 95% CI=1.31-1.97, p<0.001). However, there was no evidence of additional benefit in terms of health service use in the following year.

CONCLUSIONS

In common with other coercive treatments, people from culturally and linguistically diverse (CALD) backgrounds are more likely to be placed on CTOs. Further research is needed to establish if this is for similar reasons.

A retrospective cohort study to compare post-injury admissions for infectious diseases in burn patients, non-burn trauma patients and uninjured people

Background

Injury triggers a range of systemic effects including inflammation and immune responses. This study aimed to compare infectious disease admissions after burn and other types of injury using linked hospital admissions data.

Methods

A retrospective longitudinal study using linked health data of all patients admitted with burns in Western Australia (n = 30,997), 1980–2012, and age and gender frequency matched cohorts of people with non-burn trauma (n = 28,647) and no injury admissions (n = 123,399). Analyses included direct standardisation, negative binomial regression and Cox proportional hazards regression.

Results

Annual age-standardised infectious disease admission rates were highest for the burn cohort, followed by the non-burn trauma and uninjured cohorts. Age-standardised admission rates by decade showed different patterns across major categories of infectious diseases, with the lower respiratory and skin and soft tissue infections the most common for those with burns and other open trauma. Compared with the uninjured, those with burns had twice the admission rate for infectious disease after discharge (incident rate ratio (IRR), 95% confidence interval (CI): 2.04, 1.98–2.11) while non-burn trauma experienced 1.74 times higher rates (95%CI: 1.68–1.81). The burn cohort experienced 10% higher rates of first-time admissions after discharge when compared with the non-burn trauma (hazard ratio (HR), 95%CI: 1.10, 1.05–1.15). Compared with the uninjured cohort, incident admissions were highest during the first 30 days after discharge for burns (HR, 95%CI: 5.18, 4.15–6.48) and non-burn trauma (HR, 95%CI: 5.06, 4.03–6.34). While incident rates remained high over the study period, the magnitude decreased with increasing time from discharge: burn vs uninjured: HR, 95%CI: 30 days to 1 year: 1.69, 1.53–1.87; 1 to 10 years: 1.40, 1.33–1.47; 10 years to end of study period: 1.16, 1.08–1.24; non-burn trauma vs uninjured: HR, 95%CI: 30 days to 1 year: 1.71, 1.55–1.90; 1 to 10 years: 1.30, 1.24–1.37; 10 years to end of study period: 1.09, 1.03–1.17).

Conclusions

Burns and non-burn trauma patients had higher admission rates for infectious diseases compared with age and gender matched uninjured people. The pattern of annual admission rates for major categories of infectious diseases varied across injury groups. Overall, the burn cohort experienced the highest rates for digestive, lower respiratory and skin and soft tissue infections. These results suggest long-term vulnerability to infectious disease after injury, possibly related to long-term immune dysfunction.

Determinants of infant mortality for children of women prisoners: a longitudinal linked data study

BACKGROUND

There is limited information on the determinants of infant mortality outcomes for the children of women prisoners. This study aimed to explore determinants of infant mortality for Indigenous and non-Indigenous children, with a specific focus on maternal imprisonment during pregnancy as a risk factor.

METHODS

Using linked administrative data we obtained a longitudinal sample of 42,674 infants born in Western Australia between October 1985 and June 2013. Data were analysed by maternal contact with corrective services, including; (i) imprisonment during pregnancy, (ii) imprisonment before (but not during) pregnancy, (iii) imprisonment after birth, (iv) community-based correctional orders (but no imprisonment), and (v) no corrections record. Infant mortality rates were calculated. Univariate and multivariate log-binomial regression was undertaken to identify key demographic and pregnancy-related risk factors for infant mortality. Risk factor prevalence was calculated for infants by maternal corrections history.

RESULTS

430 Indigenous and 116 non-Indigenous infants died aged 0-12 months. For singletons, infant mortality rates were highest in Indigenous infants with mothers imprisoned during pregnancy (32.1 per 1000) and non-Indigenous infants whose mothers were first imprisoned after birth (14.2 per 1000). For all Indigenous children, the strongest determinants of infant mortality were: abruptio placentae and other placental disorders (RR = 2.85; 95%CI 1.46-5.59; p = 0.002), maternal imprisonment during pregnancy (RR = 2.55; 95%CI 1.69-3.86; p < 0.001), and multiple gestation (RR = 2.29; 95% CI1.51-3.46; p < 0.001). Indigenous and non-Indigenous infants with mothers imprisoned at any time, and particularly before or during pregnancy, experienced higher prevalence of key pregnancy risk factors.

CONCLUSIONS

This is the first comprehensive study of the determinants of infant mortality for children of women prisoners. Infants with any maternal corrections history, including community-based orders or imprisonment outside of pregnancy, had increased infant mortality. Indigenous infants whose mothers were imprisoned during pregnancy were at particular risk. There was a low incidence of infant death in the non-Indigenous sample which limited the investigation of the impact of the specific aspects of maternal corrections history on infant mortality. Non-Indigenous Infants whose mothers were imprisoned before or during pregnancy experienced higher prevalence of pregnancy risk factors than infants of mothers first imprisoned after birth.

Long-term impact of childhood hepatitis B vaccination programs on prevalence among Aboriginal and non-Aboriginal women giving birth in Western Australia

BACKGROUND/AIMS

To evaluate the long-term effect of infant and childhood hepatitis B (HBV) vaccination programs among birthing women in Western Australia.

METHODS

A cohort of Western Australian women born from 1974 to 1995 was created using Birth Registrations and Electoral Roll records. They were linked to a perinatal register and notifiable diseases register to identify women having respectively their first births between 2000 and 2012 and diagnoses of HBV infections. HBV prevalence was estimated in Aboriginal and non-Aboriginal women, and according to maternal birth year cohorts.

RESULTS

Of 66,073 women, 155 (0.23%) had a linked non-acute HBV notification. HBV prevalence was five times higher in Aboriginal women compared to their non-Aboriginal counterparts (0.92%, 95%CI 0.65-1.18 versus 0.18%, 0.15-0.21). Among Aboriginal women, after adjusting for year of giving birth and region of residence, those born in the targeted infant and school-based vaccination era (maternal year of birth 1988-1995) had an 89% lower risk (adjusted odds ratio [aOR] 0.11, 0.04-0.33) of HBV than those born in the pre-vaccination era (1974-1981). Prevalence also differed between Aboriginal women residing in rural/remote areas compared to those in major cities (aOR 3.06, 1.36-6.88). Among non-Aboriginal women, no significant difference in HBV prevalence was observed by maternal birth cohort (p = 0.20) nor by residence (p = 0.23), but there were significant differences by ethnicity with a 36-fold higher prevalence (aOR 36.08, 22.66-57.46) in non-Caucasian versus Caucasian women.

CONCLUSIONS

A significant decline in HBV prevalence in Aboriginal birthing mothers was observed following the introduction of HBV vaccination programs in Western Australia. There were also considerable disparities in prevalence between women by area of residence and ethnicity. Our findings reflect those observed in women in other Australian jurisdictions. Continued surveillance of HBV prevalence in birthing mothers will provide ongoing estimates of HBV vaccination program impact across Australia and the populations most at risk of chronic HBV.

Mortality in a cohort of remote-living Aboriginal Australians and associated factors

Objectives

We aimed to describe mortality in a cohort of remote-living Aboriginal Australians using electronic record linkage.

Methods

Between 2004 and 2006, 363 Aboriginal people living in remote Western Australia (WA) completed a questionnaire assessing medical history and behavioural risk factors. We obtained mortality records for the cohort from the WA Data Linkage System and compared them to data for the general population. We used Cox proportional hazards regression to identify predictors of mortality over a 9-year follow-up period.

Results

The leading causes of mortality were diabetes, renal failure, and ischaemic heart disease. Diabetes and renal failure accounted for 28% of all deaths. This differed from both the Australian population as a whole, and the general Indigenous Australian population. The presence of chronic disease did not predict mortality, nor did behaviours such as smoking. Only age, male sex, poor mobility, and cognitive impairment were risk factors.

Conclusions

To reduce premature mortality, public health practitioners should prioritise the prevention and treatment of diabetes and renal disease in Aboriginal people in remote WA. This will require a sustained and holistic approach.

Identifying patterns of general practitioner service utilisation and their relationship with potentially preventable hospitalisations in people with diabetes: The utility of a cluster analysis approach

AIMS

We aimed to characterise use of general practitioners (GP) simultaneously across multiple attributes in people with diabetes and examine its impact on diabetes related potentially preventable hospitalisations (PPHs).

METHODS

Five-years of panel data from 40,625 adults with diabetes were sourced from Western Australian administrative health records. Cluster analysis (CA) was used to group individuals with similar patterns of GP utilisation characterised by frequency and recency of services. The relationship between GP utilisation cluster and the risk of PPHs was examined using multivariable random-effects negative binomial regression.

RESULTS

CA categorised GP utilisation into three clusters: moderate; high and very high usage, having distinct patient characteristics. After adjusting for potential confounders, the rate of PPHs was significantly lower across all GP usage clusters compared with those with no GP usage; IRR = 0.67 (95%CI: 0.62-0.71) among the moderate, IRR = 0.70 (95%CI 0.66-0.73) high and IRR = 0.76 (95%CI 0.72-0.80) very high GP usage clusters.

CONCLUSIONS

Combination of temporal factors with measures of frequency of use of GP services revealed patterns of primary health care utilisation associated with different underlying patient characteristics. Incorporation of multiple attributes, that go beyond frequency-based approaches may better characterise the complex relationship between use of GP services and diabetes-related hospitalisation.

Exploring factors impacting early childhood health among Aboriginal and Torres Strait Islander families and communities: protocol for a population-based cohort study using data linkage (the 'Defying the Odds' study)

INTRODUCTION

Empirical evidence on family and community risk and protective factors influencing the comparatively high rates of potentially preventable hospitalisations and deaths among Aboriginal and Torres Strait Islander infants and children is limited. As is evidence on geographical variation in these risks. The 'Defying the Odds' study aims to explore the impact of perinatal outcomes, maternal social and health outcomes and level of culturally secure service availability on the health outcomes of Western Australian (WA) Aboriginal infants and children aged 0-5 years.

METHODS AND ANALYSIS

The study combines a retrospective cohort study that uses state-wide linked health and administrative data from 12 data sources for multiple generations within Aboriginal families in WA, with specifically collected survey data from health and social services supporting Aboriginal families in regions of WA. Data sources include perinatal/birth registration, hospital, emergency department, mental health services, drug and alcohol service use, mortality, infectious disease notifications, and child protection and family services. Multilevel regression models will be used to examine the intensity of admissions and presentations, mortality, intensity of long stays and morbidity-free survival (no admissions) for Aboriginal children born in WA in 2000-2013. Relationships between maternal (and grand-maternal) health and social factors and child health outcomes will be quantified. Community-level variation in outcomes for Aboriginal children and factors contributing to this variation will be examined, including the availability of culturally secure services. Online surveys were sent to staff members at relevant services to explore the scope, reach and cultural security of services available to support Aboriginal families across selected regions of WA.

ETHICS AND DISSEMINATION

Ethics approvals have been granted for the study. Interpretation and dissemination are guided by the study team's Aboriginal leadership and reference groups. Dissemination will be through direct feedback and reports to health services in the study and via scientific publications and policy recommendations.

Earlier Initiation of Community-Based Palliative Care Is Associated With Fewer Unplanned Hospitalizations and Emergency Department Presentations in the Final Months of Life: A Population-Based Study Among Cancer Decedents

CONTEXT

Although community-based palliative care (CPC) is associated with decreased acute care use in the lead up to death, it is unclear how the timing of CPC initiation affects this association.

OBJECTIVES

We aimed to explore the association between timing of CPC initiation and hospital use, over the final one, three, six, and 12 months of life.

METHODS

We conducted a retrospective, population-based study in Perth, Western Australia. Linked administrative data including cancer registry, mortality, hospital admissions, emergency department (ED), and CPC records were obtained for cancer decedents from 1 January, 2001 to 31 December, 2011. The exposure was month of CPC initiation; outcomes were unplanned hospitalizations, ED presentations, and associated costs.

RESULTS

Of 28,331 decedents residing in the CPC catchment area, 16,439 (58%) accessed CPC, mostly (64%) in the last three months of life. Initiation of CPC before the last six months of life was associated with a lower mean rate of unplanned hospitalizations in the last six months of life (1.4 vs. 1.7 for initiation within six months of death); associated costs were also lower ($(A2012) 12,976 vs. $13,959, comparing the same groups). However, those initiating CPC earlier did show a trend toward longer time in hospital when admitted, compared to those initiating in the final month of life.

CONCLUSIONS

When viewed at a population level, these results argue against temporally restricting access to CPC, as earlier initiation may pay dividends in the final few months of life in terms of fewer unplanned hospitalizations and ED presentations.

Severe lower limb cellulitis: defining the epidemiology and risk factors for primary episodes in a population-based case-control study

OBJECTIVE

To describe the epidemiology and risk factors for primary episodes of severe lower leg cellulitis (LLC).

METHODS

This was a longitudinal cohort study using state-wide data linkage of adults presenting to Western Australian (WA) hospitals with a first ever LLC from January 2002 to December 2013. The study aimed at determining risk factors, medical records from the index patient, together with comparable data from controls matched by age, sex, postcode, and month of admission.

RESULTS

During the period, 36 276 patients presented with their first episode of LLC. The incidence increased by 4.7% per annum, reaching 204.8 (95% CI 198.6-211.1) per 100 000 population by December 2013. Analysis of 29 062 case-control pairs showed several conditions with lower limb pathology were independently associated with LLC, including varicose veins (AOR 2.95, 95% CI 2.50-3.48, p < 0.001), lymphoedema (AOR 2.65, 95% CI 1.71-4.10, p < 0.001), tinea pedis (AOR 3.05, 95% CI 1.45-6.42, p 0.003), and saphenous vein harvest during coronary artery bypass grafting (AOR 1.74, 95% CI 1.32-2.30, p < 0.001). Also associated with LLC was obesity (AOR 2.05, 95% CI 1.82-2.31, p < 0.001), renal disease (AOR 1.28, 95% CI 1.14-1.44, p < 0.001), rheumatologic conditions (AOR 2.12, 95% CI 1.72-2.60, p < 0.001), hemiplegia/paraplegia (AOR 1.31, 95% CI 1.13-1.52, p < 0.001), and liver disease (AOR 1.77, 95% CI 1.51-2.06, p < 0.001).

CONCLUSIONS

LLC presents a major burden to the health sector and is increasing with an ageing population. Given the high rates of recurrence, long-term morbidity, and economic impact, efforts to reduce primary episodes should be incorporated into the infectious diseases and healthy ageing research agenda.

Validation of intellectual disability coding through hospital morbidity records using an intellectual disability population-based database in Western Australia

OBJECTIVES

To investigate how well intellectual disability (ID) can be ascertained using hospital morbidity data compared with a population-based data source.

DESIGN, SETTING AND PARTICIPANTS

All children born in 1983-2010 with a hospital admission in the Western Australian Hospital Morbidity Data System (HMDS) were linked with the Western Australian Intellectual Disability Exploring Answers (IDEA) database. The International Classification of Diseases hospital codes consistent with ID were also identified.

MAIN OUTCOME MEASURES

The characteristics of those children identified with ID through either or both sources were investigated.

RESULTS

Of the 488 905 individuals in the study, 10 218 (2.1%) were identified with ID in either IDEA or HMDS with 1435 (14.0%) individuals identified in both databases, 8305 (81.3%) unique to the IDEA database and 478 (4.7%) unique to the HMDS dataset only. Of those unique to the HMDS dataset, about a quarter (n=124) had died before 1 year of age and most of these (75%) before 1 month. Children with ID who were also coded as such in the HMDS data were more likely to be aged under 1 year, female, non-Aboriginal and have a severe level of ID, compared with those not coded in the HMDS data. The sensitivity of using HMDS to identify ID was 14.7%, whereas the specificity was much higher at 99.9%.

CONCLUSION

Hospital morbidity data are not a reliable source for identifying ID within a population, and epidemiological researchers need to take these findings into account in their study design.

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

BACKGROUND

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.

METHODS

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.

FINDINGS

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).

INTERPRETATION

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.

FUNDING

Australian National Health and Medical Research Council.

Maternal incarceration, child protection, and infant mortality: a descriptive study of infant children of women prisoners in Western Australia

BACKGROUND

There are no population statistics collected on a routine basis on the children of prisoners in Australia. Accordingly, their potential vulnerability to adverse outcomes remains unclear. This study draws on linked administrative data to describe the exposure of children aged less than 2 years to maternal imprisonment in Western Australia, their contact with child protection services, and infant mortality rates.

RESULTS

In Western Australia, 36.5 per 1000 Indigenous (n = 804) and 1.3 per 1000 non-Indigenous (n = 395) children born between 2001 and 2011 had mothers imprisoned after birth to age 2 years. One-third of infants' mothers had multiple imprisonments (maximum of 11). Nearly half (46%) of prison stays were for ≤2 weeks, 12% were between 2 and 4 weeks, 14% were for 1-3 months, and 28% were longer than three months. Additionally, 17.4 per 1000 Indigenous (n = 383) and 0.5 per 1000 non-Indigenous (n = 150) children had mothers imprisoned during pregnancy. Half of the children with a history of maternal incarceration in pregnancy to age 2 years came into contact with child protection services by their second birthday, with 31% of Indigenous and 35% of non-Indigenous children entering out-of-home care. Rates of placement in care were significantly higher for Indigenous children (Relative Risk (RR) 27.30; 95%CI 19.19 to 38.84; p < .001) and for non-Indigenous children (RR 110.10; 95%CI 61.70 to 196.49; p < .001) with a history of maternal imprisonment compared to children of mothers with no corrections record. Infant mortality for children whose mothers were imprisoned up to 5 years before birth or within their first year after birth was higher than for children of mothers with no corrections record for both Indigenous (RR 2.36; 95%CI 1.41 to 3.95; p = .001) and non-Indigenous children (RR 2.28; 95%CI 0.75 to 6.97; p = .147).

CONCLUSIONS

This study highlights the particular vulnerability of children whose mothers have been incarcerated and the importance of considering their needs within corrective services policies and procedures. Prison may present an opportunity to identify and work with vulnerable families to help improve outcomes for children as well as mothers.

Diabetes mellitus after injury in burn and non-burned patients: A population based retrospective cohort study

OBJECTIVE

To compare hospitalisations for diabetes mellitus (DM) after injury experienced by burn patients, non-burn trauma patients and people with no record of injury admission, adjusting for socio-demographic, health and injury factors.

METHODS

Linked hospital and death data for a burn patient cohort (n=30,997) in Western Australia during the period 1980-2012 and two age and gender frequency matched comparison cohorts: non-burn trauma patients (n=28,647); non-injured people (n=123,399). The number of DM admissions and length of stay were used as outcome measures. Multivariate negative binomial regression was used to derive adjusted incidence rate ratios and 95% confidence intervals (IRR, 95%CI) for overall post-injury DM admission rates. Multivariate Cox regression models and hazard ratios (HR) were used to examine time to first DM admission and incident admission rates after injury discharge.

RESULTS

The burn cohort (IRR, 95%: 2.21, 1.80-2.72) and other non-burn trauma cohort (IRR, 95%CI: 1.63, 1.24-2.14) experienced significantly higher post-discharge admission rates for DM than non-injured people. Compared with the non-burn trauma cohort, the burn cohort experienced a higher rate of post-discharge DM admissions (IRR, 95%CI: 1.40, 1.07-1.84). First-time DM admissions were significantly higher during first 5-years after-injury for the burn cohort compared with the non-burn trauma cohort (HR, 95%CI: 2.00, 1.31-3.05) and non-injured cohort (HR, 95%CI: 1.96, 1.46-2.64); no difference was found >5years (burn vs. non-burn trauma: HR, 95%CI: 0.88, 0.70-1.12; burn vs non-injured: 95%CI: 1.08 0.82-1.41). No significant difference was found when comparing the non-burn trauma and non-injured cohorts (0-5 years: HR, 95%CI: 1.03, 0.71-1.48; >5years: HR. 95%CI: 1.11, 0.93-1.33).

CONCLUSIONS

Burn and non-burn trauma patients experienced elevated rates of DM admissions after injury compared to the non-injured cohort over the duration of the study. While burn patients were at increased risk of incident DM admissions during the first 5-years after the injury this was not the case for non-burn trauma patients. Sub-group analyses showed elevated risk in both adult and pediatric patients in the burn and non-burn trauma. Detailed clinical data are required to help understand the underlying pathogenic pathways triggered by burn and non-burn trauma. This study identified treatment needs for patients after burn and non-burn trauma for a prolonged period after discharge.

Reducing Bruzzi's Formula to Remove Instability in the Estimation of Population Attributable Fraction for Health Outcomes

The aim of this study was to reconcile 3 approaches to calculating population attributable fractions and attributable burden percentage: the approach of Bruzzi et al. (Am J Epidemiol. 1985;122(5):904-914.), the maximum-likelihood method of Greenland and Drescher (Biometrics. 1993;49(3):865-872.), and the multivariable method of Tanuseputro et al. (Popul Health Metr. 2015;13:5.). Using data from a statewide point prevalence survey (Western Australian Point Prevalence Survey, 2014) linked to an administrative database, we compared estimates of attributable burden percentage obtained using the contrasting methods in 6 logistic models of health outcomes from the survey, estimating 95% confidence intervals using nonparametric and weighted bootstrap approaches. Our results show that instability can arise from the fundamental algebraic construction of Bruzzi's formula, and that this instability may substantially influence the calculation of attributable burden percentage and associated confidence intervals. These observations were confirmed in a simulation study. The algebraic reduction of Bruzzi's formula to the 2 alternative methods resulted in markedly more stable estimates for population attributable fraction and attributable burden percentage in cross-sectional studies and cohort designs with fixed follow-up time. We advocate the widespread implementation of the maximum-likelihood approach and the multivariable method.

Serum 25-hydroxyvitamin D as a predictor of mortality and cardiovascular events: A 20-year study of a community-based cohort

OBJECTIVE

Prospective studies, mostly from Europe and North America, suggest that serum 25-hydroxyvitamin D (25(OH)D) is inversely associated with mortality and cardiovascular disease (CVD) risk. Data from other regions are limited, and threshold levels for adverse cardiovascular outcomes are uncertain. We examined serum 25(OH)D as a predictor of total mortality and cardiovascular outcomes in an Australian cohort.

DESIGN

A 20-year, community-based cohort study.

PATIENTS

Participants in the 1994/1995 Busselton Health Survey (n = 3946, baseline age 25-84 years).

MEASUREMENTS

Baseline serum 25(OH)D and mortality and cardiovascular outcomes to 2014 obtained by record linkage.

RESULTS

The mean serum 25(OH)D concentration was 60.6 ± 18.0 nmol/L. During 20-year follow-up (excluding the first 2 years), 889 participants died (including 363 from CVD) and 944 experienced a CVD event (including 242 with heart failure). In the full cohort, controlling for Framingham risk score variables, higher baseline 25(OH)D was associated with significantly reduced all-cause mortality (adjusted HR 0.83 per SD increment of 25(OH)D, 95% CI 0.77-0.90), CVD death (HR 0.85, 95% CI 0.74-0.96) and heart failure (HR 0.81, 95% CI 0.69-0.94), but not CVD events (HR 0.99, 0.92-1.07). In restricted cubic spline regression models, serum 25(OH)D below 65 and 55 nmol/L was associated with higher total mortality and higher CVD mortality/heart failure, respectively. In participants without CVD at baseline (n = 3220), results were similar, but hazard ratios were attenuated and associations with CVD mortality no longer significant.

CONCLUSIONS

In an Australian community-based cohort, baseline vitamin D levels below 55-65 nmol/L are predictive of all-cause mortality, CVD death and heart failure.

Risk and associates of incident hip fracture in type 1 diabetes: The Fremantle Diabetes Study

AIMS

To determine the relative risk of incident hip fracture in patients with type 1 diabetes and matched controls, to examine baseline associates of incident hip fracture in the patients with type 1 diabetes, and to compare hip fracture rates in age- and sex-matched patients with type 1 versus type 2 diabetes.

METHODS

Longitudinal observational study of 121 adults with type 1 diabetes (mean ± SD age 43.0 ± 15.5 years, 59.5% male) and 484 age- and sex-matched adults without diabetes. Age and sex matching was possible for 93 pairs of type 1 and type 2 participants. The main outcome measure was incident hip fracture hospitalisation.

RESULTS

During a mean ± SD 14.5 ± 5.8 years of follow-up, the incidence rate ratio for first hip fracture hospitalisation in type 1 participants versus residents without diabetes was 6.39 (95% CI 1.94-22.35, P < .001). In Cox proportional hazards modelling, type 1 diabetes was associated with cause-specific hazard ratio (csHR) for hip fracture of 7.11 (2.45-20.64, P < .001) after age and sex adjustment. Hip fracture in type 1 participants was associated with older age, osteoporosis treatment, depressive symptoms, ethnicity, systolic blood pressure, serum HDL-cholesterol, albuminuria and serum adiponectin (P ≤ 0.047); associations remained for the first three of these variables after adjustment for age and body mass index (P ≤ 0.025). The csHR for incident hip fracture was 5.32 (1.12-25.37, P = .036) for type 1 versus 2 diabetes.

CONCLUSIONS

Hip fracture risk is markedly elevated in type 1 diabetes compared with age and sex-matched individuals without diabetes and with type 2 diabetes from the same population.

Patient healthcare trajectory. An essential monitoring tool: a systematic review

BACKGROUND

Patient healthcare trajectory is a recent emergent topic in the literature, encompassing broad concepts. However, the rationale for studying patients' trajectories, and how this trajectory concept is defined remains a public health challenge. Our research was focused on patients' trajectories based on disease management and care, while also considering medico-economic aspects of the associated management. We illustrated this concept with an example: a myocardial infarction (MI) occurring in a patient's hospital trajectory of care. The patient follow-up was traced via the prospective payment system. We applied a semi-automatic text mining process to conduct a comprehensive review of patient healthcare trajectory studies. This review investigated how the concept of trajectory is defined, studied and what it achieves.

METHODS

We performed a PubMed search to identify reports that had been published in peer-reviewed journals between January 1, 2000 and October 31, 2015. Fourteen search questions were formulated to guide our review. A semi-automatic text mining process based on a semantic approach was performed to conduct a comprehensive review of patient healthcare trajectory studies. Text mining techniques were used to explore the corpus in a semantic perspective in order to answer non-a priori questions. Complementary review methods on a selected subset were used to answer a priori questions.

RESULTS

Among the 33,514 publications initially selected for analysis, only 70 relevant articles were semi-automatically extracted and thoroughly analysed. Oncology is particularly prevalent due to its already well-established processes of care. For the trajectory thema, 80% of articles were distributed in 11 clusters. These clusters contain distinct semantic information, for example health outcomes (29%), care process (26%) and administrative and financial aspects (16%).

CONCLUSION

This literature review highlights the recent interest in the trajectory concept. The approach is also gradually being used to monitor trajectories of care for chronic diseases such as diabetes, organ failure or coronary artery and MI trajectory of care, to improve care and reduce costs. Patient trajectory is undoubtedly an essential approach to be further explored in order to improve healthcare monitoring.

Hospital admissions for skin infections among Western Australian children and adolescents from 1996 to 2012

The objective of this study was to describe the occurrence of skin infection associated hospitalizations in children born in Western Australia (WA). We conducted a retrospective cohort study of all children born in WA between 1996 and 2012 (n = 469,589). Of these, 31,348 (6.7%) were Aboriginal and 240,237 (51.2%) were boys. We report the annual age-specific hospital admission rates by geographical location and diagnostic category. We applied log-linear regression modelling to analyse changes in temporal trends of hospitalizations. Hospitalization rates for skin infections in Aboriginal children (31.7/1000 child-years; 95% confidence interval [CI] 31.0–32.4) were 15.0 times higher (95% CI 14.5–15.5; P<0.001) than those of non-Aboriginal children (2.1/1000 child-years; 95% CI 2.0–2.1). Most admissions in Aboriginal children were due to abscess, cellulitis and scabies (84.3%), while impetigo and pyoderma were the predominant causes in non-Aboriginal children (97.7%). Admissions declined with age, with the highest rates for all skin infections observed in infants. Admissions increased with remoteness. Multiple admissions were more common in Aboriginal children. Excess admissions in Aboriginal children were observed during the wet season in the Kimberley and during summer in metropolitan areas. Our study findings show that skin infections are a significant cause of severe disease, requiring hospitalization in Western Australian children, with Aboriginal children at a particularly high risk. Improved community-level prevention of skin infections and the provision of effective primary care are crucial in reducing the burden of skin infection associated hospitalizations. The contribution of sociodemographic and environmental risk factors warrant further investigation.

Body Mass Index and Vascular Disease in Men Aged 65 Years and Over: HIMS (Health In Men Study)

BACKGROUND

Understanding the relationship between body mass index (BMI) and vascular disease at older age has become increasingly important in the many countries where both average age and BMI are rising.

METHODS AND RESULTS

In this prospective cohort study, 12 203 men (aged ≥65) were recruited in 1996-1999 from the general population in Perth, Australia. To limit reverse causality, analyses excluded those with past vascular disease and the first 4 years of follow-up. During a further 8 (SD3) years of follow-up, there were 1136 first-ever major vascular events (nonfatal myocardial infarction, nonfatal stroke, or death from any vascular cause). Cox regression (adjusted for age, education, and smoking) related BMI at recruitment to incidence of major vascular events. At ages 65 to 94, the lowest risk of major vascular events was at ≈ 22.5 to 25 kg/m². In the higher BMI range (≥25 kg/m²), 5 kg/m² higher BMI was associated with 33% higher risk of major vascular events (hazard ratio, 1.33 [95% confidence interval, 1.18-1.49]): 24% higher risk of ischemic heart disease (1.24 [1.06-1.46]); 34% higher risk of stroke (1.34 [1.11-1.63]); and 78% higher risk of other vascular death (1.78 [1.32-2.41]). In the lower BMI range, there were fewer events and no strong evidence of an association (hazard ratio per 5 kg/m² higher BMI, 0.82 [95% confidence interval, 0.61-1.12]).

CONCLUSIONS

In this population of older men, risk of major vascular events was lowest at ≈ 22.5 to 25 kg/m². Above this range, BMI was strongly related to incidence of major vascular events, with each 5 kg/m² higher BMI associated with ≈30% higher risk.

Declining rates of sterilisation reversal procedures in western Australian women from 1990 to 2008: the relationship with age, hospital type and government policy changes

BACKGROUND

Female sterilisation is usually performed on an elective basis at perceived family completion, however, around 1-3% of women who have undergone sterilisation elect to undergo sterilisation reversal (SR) at a later stage. The trends in SR rates in Western Australia (WA), proportions of SR procedures between hospital types (public and private), and the effects of Federal Government policies on these trends are unknown.

METHODS

Using records from statutory state-wide data collections of hospital separations and births, we conducted a retrospective descriptive study of all women aged 15-49 years who underwent a SR procedure during the period 1st January 1990 to 31st December 2008 (n = 1868 procedures).

RESULTS

From 1991 to 2007 the annual incidence rate of SR procedures per 10,000 women declined from 47.0 to 3.6. Logistic regression modelling showed that from 1997 to 2001 the odds of women undergoing SR in a private hospital as opposed to all other hospitals were 1.39 times higher (95% CI 1.07-1.81) and 7.51 times higher (95% CI 5.46-10.31) from 2002 to 2008. There were significant decreases in SR rates overall and among different age groups after the Federal Government interventions.

CONCLUSION

Rates of SR procedures in WA have declined from 1990 to 2008, particularly following policy changes such as the introduction of private health insurance (PHI) policies. This suggests decisions to undergo SR may be influenced by Federal Government interventions.

Mothers of Children with Autism have Different Rates of Cancer According to the Presence of Intellectual Disability in Their Child

Autism spectrum disorder (ASD) and intellectual disability (ID) are neurodevelopmental disorders with strong genetic components. Increasingly, research attention has focused on whether genetic factors conveying susceptibility for these conditions, also influence the risk of other health conditions, such as cancer. We examined the occurrence of hospital admissions and treatment/services for cancer in mothers of children with ASD with or without ID compared with other mothers. After linking Western Australian administrative health databases, we used Cox regression to estimate the hazard ratios (HRs) of any hospitalisations and treatment/services for cancer in these groups of mothers. Mothers of children with ASD without ID had greater risk of admissions for cancer (HR 1.29 [95 % CI 1.1, 1.7]), and for treatment/services in particular (HR 1.41 [95 % CI 1.0, 2.0]), than mothers of children with no ASD/ID, while mothers of children with ASD with ID were no more likely to have a cancer-related hospital admission than other mothers. Mothers of children with autism without ID had increased risk of cancer, which may relate to common genetic pathways.

Record linkage study of the pathogen-specific burden of respiratory viruses in children

Background

Reliance on hospital discharge diagnosis codes alone will likely underestimate the burden of respiratory viruses.

Objectives

To describe the epidemiology of respiratory viruses more accurately, we used record linkage to examine data relating to all children hospitalized in Western Australia between 2000 and 2012.

Patients/Methods

We extracted hospital, infectious disease notification and laboratory data of a cohort of children born in Western Australia between 1996 and 2012. Laboratory records of respiratory specimens collected within 48 hours of admission were linked to hospitalization records. We calculated the frequency and rates of virus detection. To identify groups where under‐ascertainment for respiratory viruses was greatest, we used logistic regression to determine factors associated with failure to test.

Results and conclusions

Nine percentage of 484 992 admissions linked to a laboratory record for respiratory virus testing. While 62% (n = 26 893) of laboratory‐confirmed admissions received respiratory infection diagnosis codes, 38% (n = 16 734) had other diagnoses, notably viral infection of unspecified sites. Of those tested, incidence rates were highest for respiratory syncytial virus (247 per 100 000 child‐years) followed by parainfluenza (63 per 100 000 child‐years). Admissions among older children and those without a respiratory diagnosis were associated with failure to test for respiratory viruses. Linked data can significantly enhance diagnostic codes when estimating the true burden of disease. In contrast to current emphasis on influenza, respiratory syncytial virus and parainfluenza were the most common viral pathogens among hospitalized children. By characterizing those failing to be tested, we can begin to quantify the under‐ascertainment of respiratory viruses.

High-sensitivity cardiac troponin I and risk of cardiovascular disease in an Australianpopulation-based cohort

Objective

High-sensitivity cardiac troponin I (hs-cTnI) is an emerging biomarker for cardiovascular risk. We examined hs-cTnI as a predictor of mortality and cardiovascular outcomes in an Australian population-based cohort and evaluated if a sex difference exists.

Methods

Serum hs-cTnI was measured in the Busselton Health Study 1994/1995 Cohort (n=3939). Outcome measures were total and cardiovascular mortality, cardiovascular disease (CVD) and coronary heart disease (CHD) events, heart failure and stroke.

Results

Hs-cTnI was detectable (>1.2 ng/L) in 66.1% of participants (males 81.8%, females 54.4%) at baseline. There were 886 deaths (including 361 from CVD) and 940 CVD events during 20-year follow-up. Adjusting for Framingham Risk Score variables, hs-cTnI was a significant predictor of total mortality (HR (95% CI): 1.16 (1.09 to 1.24)), CVD mortality (1.33 (1.23 to 1.44)), CVD events (1.18 (1.11 to 1.25)), CHD events (1.11 (1.03 to 1.20)), heart failure (1.44 (1.31 to 1.58)) and stroke (1.13 (1.03 to 1.24)) per doubling of hs-cTnI at baseline. HRs remained significant in CVD-free individuals at baseline (n=3215), except for CHD events. There were no significant interactions between sex and hs-cTnI as a predictor of outcomes. Compared with individuals with hs-cTnI ≤1.2 ng/L, men with hs-cTnI ≥6.0 ng/L and women with hs-cTnI ≥4.0 ng/L had an HR of 2.18 (1.42 to 3.37) and 1.84 (1.30 to 2.62), respectively, for any CVD event, which persisted in the CVD-free subgroup.

Conclusions

Cardiac troponin I, measured with a high-sensitive assay, is an independent predictor of fatal and non-fatal CVD events and may help identify at-risk individuals in a general population.

Clusters of suicides and suicide attempts: detection, proximity and correlates

BACKGROUND

A suicide cluster is defined as a higher number of observed cases occurring in space and/or time than would typically be expected. Previous research has largely focused on identifying clusters of suicides, while there has been comparatively limited research on clusters of suicide attempts. We sought to identify clusters of both types of behaviour, and having done that, identify the factors that distinguish suicide attempts inside a cluster from those that were outside a cluster.

METHODS

We used data from Western Australia from 2000 to 2011. We defined suicide attempts as admissions to hospital for deliberate self-harm and suicides as deaths due to deliberate self-harm. Using an analytic strategy that accounted for the repetition of attempted suicide within a cluster, we performed spatial-temporal analysis using Poisson discrete scan statistics to detect clusters of suicide attempts and clusters of suicides. Logistic regression was then used to compare clustered attempts with non-clustered attempts to identify risk factors for an attempt being in a cluster.

RESULTS

We detected 350 (1%) suicide attempts occurring within seven spatial-temporal clusters and 12 (0.6%) suicides occurring within two spatial-temporal clusters. Both of the suicide clusters were located within a larger but later suicide attempt cluster. In multivariate analysis, suicide attempts by individuals who lived in areas of low socioeconomic status had higher odds of being in a cluster than those living in areas of high socioeconomic status [odds ratio (OR) = 29.1, 95% confidence interval (CI) = 6.3-135.5]. A one percentage-point increase in the proportion of people who had changed address in the last year was associated with a 60% increase in the odds of the attempt being within a cluster (OR = 1.60, 95% CI = 1.29-1.98) and a one percentage-point increase in the proportion of Indigenous people in the area was associated with a 7% increase in the suicide being within a cluster (OR = 1.07, 95% CI = 1.00-1.13). Age, sex, marital status, employment status, method of harm, remoteness, percentage of people in rented accommodation and percentage of unmarried people were not associated with the odds of being in a suicide attempt cluster.

CONCLUSIONS

Early identification of and responding to suicide clusters may reduce the likelihood of subsequent clusters forming. The mechanisms, however, that underlie clusters forming is poorly understood.

Lower TSH and higher free thyroxine predict incidence of prostate but not breast, colorectal or lung cancer

CONTEXT

Thyroid hormones modulate proliferative, metabolic and angiogenic pathways. However few studies have examined associations of thyroid hormones with cancer risk.

OBJECTIVES

To explore associations of thyrotropin (TSH), free thyroxine (FT4) and anti-thyroperoxidase antibodies (TPOAb) with the incidence of all (non-skin) cancers and specific common cancers.

DESIGN AND SETTING

A prospective cohort study of a community-dwelling population aged 25-84 years in Western Australia.

MAIN OUTCOME MEASURES

Archived sera from 3649 participants in the 1994/1995 Busselton Health Survey were assayed for TSH, FT4 and TPOAb. Cancer outcomes until 30 June 2014 were ascertained using data linkage. Longitudinal analyses were performed using Cox proportional hazards regression.

RESULTS

During 20-year follow-up, 600 participants were diagnosed with non-skin cancer, including 126, 100, 103 and 41 prostate, breast, colorectal and lung cancers respectively. Higher TSH was associated with a lower risk of prostate cancer after adjusting for potential confounders, with a 30% lower risk for every 1 IU/L increase in TSH (adjusted hazard ratio (HR): 0.70, 95% confidence interval (CI): 0.55-0.90, P = 0.005). Similarly, higher FT4 was associated with an increased risk of prostate cancer (adjusted HR: 1.11 per 1 pmol/L increase, 95% CI: 1.03-1.19, P = 0.009). There were no associations of TSH, FT4 or TPOAb with all non-skin cancer events combined, or with breast, colorectal or lung cancer.

CONCLUSION

In a community-dwelling population, lower TSH and higher FT4 were associated with an increased risk of prostate cancer. Further studies are required to assess if thyroid function is a biomarker or risk factor for prostate cancer.

Ambulance attendances resulting from self-harm after release from prison: a prospective data linkage study

OBJECTIVE

Incarcerated adults are at high risk of self-harm and suicide and remain so after release into the community. The aims of this study were to estimate the number of ambulance attendances due to self-harm in adults following release from prison, and to identify factors predictive of such attendances.

METHODS

Baseline surveys with 1309 adults within 6 weeks of expected release from prison between 2008 and 2010 were linked prospectively with state-wide correctional, ambulance, emergency department, hospital and death records in Queensland, Australia. Associations between baseline demographic, criminal justice and mental health-related factors, and subsequent ambulance attendances resulting from self-harm, were investigated using negative binomial regression.

RESULTS

During 4691 person-years of follow-up (median 3.86 years per participant), there were 2892 ambulance attendances in the community, of which 120 (3.9%) were due to self-harm. In multivariable analyses, being Indigenous [incidence rate ratio (IRR): 2.10 (95% CI 1.14-3.86)], having previously been hospitalised for psychiatric treatment [IRR: 2.65 (95% CI 1.44-4.87)], being identified by prison staff as being at risk of self-harm whilst incarcerated [IRR: 2.12 (95% CI 1.11-4.06)] and having a prior ambulance attendance due to self-harm [IRR: 3.16 (95% CI 1.31-7.61)] were associated with self-harm attendances.

CONCLUSIONS

Ambulance attendances resulting from self-harm following release from prison are common and represent an opportunity for tertiary intervention for self-harm. The high prevalence of such attendances, in conjunction with the strong association with prior psychiatric problems, reinforces the importance of providing appropriate ambulance staff training in the assessment and management of self-harm, and mental health problems more broadly, in this vulnerable population.

Potential impact of a maternal vaccine for RSV: A mathematical modelling study

Respiratory syncytial virus (RSV) is a major cause of respiratory morbidity and one of the main causes of hospitalisation in young children. While there is currently no licensed vaccine for RSV, a vaccine candidate for pregnant women is undergoing phase 3 trials. We developed a compartmental age-structured model for RSV transmission, validated using linked laboratory-confirmed RSV hospitalisation records for metropolitan Western Australia. We adapted the model to incorporate a maternal RSV vaccine, and estimated the expected reduction in RSV hospitalisations arising from such a program. The introduction of a vaccine was estimated to reduce RSV hospitalisations in Western Australia by 6-37% for 0-2month old children, and 30-46% for 3-5month old children, for a range of vaccine effectiveness levels. Our model shows that, provided a vaccine is demonstrated to extend protection against RSV disease beyond the first three months of life, a policy using a maternal RSV vaccine could be effective in reducing RSV hospitalisations in children up to six months of age, meeting the objective of a maternal vaccine in delaying an infant's first RSV infection to an age at which severe disease is less likely.

Impact of family-friendly prison policies on health, justice and child protection outcomes for incarcerated mothers and their dependent children: a cohort study protocol

INTRODUCTION

Female imprisonment has numerous health and social sequelae for both women prisoners and their children. Examples of comprehensive family-friendly prison policies that seek to improve the health and social functioning of women prisoners and their children exist but have not been evaluated. This study will determine the impact of exposure to a family-friendly prison environment on health, child protection and justice outcomes for incarcerated mothers and their dependent children.

METHODS AND ANALYSIS

A longitudinal retrospective cohort design will be used to compare outcomes for mothers incarcerated at Boronia Pre-release Centre, a women's prison with a dedicated family-friendly environment, and their dependent children, with outcomes for mothers incarcerated at other prisons in Western Australia (that do not offer this environment) and their dependent children. Routinely collected administrative data from 1985 to 2013 will be used to determine child and mother outcomes such as hospital admissions, emergency department presentations, custodial sentences, community service orders and placement in out-of home care. The sample consists of all children born in Western Australia between 1 January 1985 and 31 December 2011 who had a mother in a West Australian prison between 1990 and 2012 and their mothers. Children are included if they were alive and aged less than 18 years at the time of their mother's incarceration. The sample comprises an exposed group of 665 women incarcerated at Boronia and their 1714 dependent children and a non-exposed comparison sample of 2976 women incarcerated at other West Australian prisons and their 7186 dependent children, creating a total study sample of 3641 women and 8900 children.

ETHICS AND DISSEMINATION

This project received ethics approval from the Western Australian Department of Health Human Research Ethics Committee, the Western Australian Aboriginal Health Ethics Committee and the University of Western Australia Human Research Ethics Committee.

Quantifying sources of bias in longitudinal data linkage studies of child abuse and neglect: measuring impact of outcome specification, linkage error, and partial cohort follow-up

Background

Health informatics projects combining statewide birth populations with child welfare records have emerged as a valuable approach to conducting longitudinal research of child maltreatment. The potential bias resulting from linkage misspecification, partial cohort follow-up, and outcome misclassification in these studies has been largely unexplored. This study integrated epidemiological survey and novel administrative data sources to establish the Alaska Longitudinal Child Abuse and Neglect Linkage (ALCANLink) project. Using these data we evaluated and quantified the impact of non-linkage misspecification and single source maltreatment ascertainment use on reported maltreatment risk and effect estimates.

Methods

The ALCANLink project integrates the 2009–2011 Alaska Pregnancy Risk Assessment Monitoring System (PRAMS) sample with multiple administrative databases through 2014, including one novel administrative source to track out-of-state emigration. For this project we limited our analysis to the 2009 PRAMS sample. We report on the impact of linkage quality, cohort follow-up, and multisource outcome ascertainment on the incidence proportion of reported maltreatment before age 6 and hazard ratios of selected characteristics that are often available in birth cohort linkage studies of maltreatment.

Results

Failure to account for out-of-state emigration biased the incidence proportion by 12% (from 28.3%_w to 25.2%_w), and the hazard ratio (HR) by as much as 33% for some risk factors. Overly restrictive linkage parameters biased the incidence proportion downwards by 43% and the HR by as much as 27% for some factors. Multi-source linkages, on the other hand, were of little benefit for improving reported maltreatment ascertainment.

Conclusion

Using the ALCANLink data which included a novel administrative data source, we were able to observe and quantify bias to both the incidence proportion and HR in a birth cohort linkage study of reported child maltreatment. Failure to account for out-of-state emigration and low-quality linkage methods may induce bias in longitudinal data linkage studies of child maltreatment which other researchers should be aware of. In this study multi-agency linkage did not lead to substantial increased detection of reported maltreatment. The ALCANLink methodology may be a practical approach for other states interested in developing longitudinal birth cohort linkage studies of maltreatment that requires limited resources to implement, provides comprehensive data elements, and can facilitate comparability between studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s40621-017-0119-6) contains supplementary material, which is available to authorized users.

Association Between High-Sensitivity Cardiac Troponin I and Cardiac Events in Elderly Women

Background

Elderly women are at high risk of coronary heart disease (CHD) and heart failure. High‐sensitivity assays allow detection of cardiac troponin I (hsTnI) well below diagnostic cutoffs for acute coronary syndrome. We investigated the association between these levels with future cardiac events in community‐based ambulant white women aged over 70 years initially recruited for a 5‐year randomized, controlled trial of calcium supplements.

Methods and Results

This was a prospective study of 1081 elderly women without clinical CHD at baseline (1998) or hsTnI above the diagnostic cutoffs for acute coronary syndrome with 14.5‐year follow‐up hospitalization and mortality (events). Two hundred forty‐three (22%) women had CHD events, 163 (15%) myocardial infarction or CHD death (hard CHD), and 109 (10%) heart failure. In 99.6% of available serum samples, hsTnI was above the level of detection (median, 4.5 ng/L; interquartile range, 3.6–5.8). After adjusting for Framingham risk factors, each SD natural log‐transformed hsTnI increase was associated with an increased hazard for CHD (hazard ratio, 1.34; 95% CI, 1.18–1.53; P<0.001) hard CHD (hazard ratio, 1.51; 95% CI, 1.29–1.76; P<0.001), and heart failure (hazard ratio, 1.65; 95% CI, 1.36–1.99; P<0.001). Step‐wise increases in relative hazards were observed with increasing quartiles of hsTnI (P for trend, <0.001), whereas the addition of hsTnI to conventional risk factors modestly improved discrimination indices: Harrell's c‐statistic, net reclassification, and integrated discrimination (P<0.05).

Conclusions

Cardiac troponin I is independently associated with future cardiac events in elderly women without apparent clinical manifestations. The addition of cardiac troponin I to conventional risk factors may modestly improve risk prediction in this setting.

Maternal alcohol use disorder and child school attendance outcomes for non-Indigenous and Indigenous children in Western Australia: a population cohort record linkage study

OBJECTIVES

Examine the relationship between maternal alcohol use disorder and child school attendance outcomes for non-Indigenous and Indigenous children in Western Australia.

DESIGN

Population cohort study.

SETTING

Routinely collected linked administrative health, education and child protection data.

PARTICIPANTS

Those in-scope for the study were women with a birth recorded on the Western Australian Midwives Notification System (1989-2007). Women who had an alcohol-related diagnosis (International Classification of Diseases Revisions 9/10) recorded on the Hospital Morbidity, Mental Health Inpatients and Outpatients, and Drug and Alcohol Office data sets formed the exposed group. The comparison cohort was frequency-matched to the exposed cohort based on maternal age within Indigenous status and child's year of birth.

PRIMARY OUTCOME MEASURE

Child's school attendance was obtained from the Department of Education (2008-2012). Poor attendance was defined as <80% attendance for non-Indigenous children and <60% attendance for Indigenous children.

RESULTS

11 430 exposed children and 26 850 unexposed children had a linked attendance record. Maternal alcohol use disorder was significantly associated with increased odds of poor attendance (non-Indigenous: OR=1.61, 95% CI 1.50 to 1.74; Indigenous: OR=1.66, 95% CI 1.54 to 1.79). With adjustment for maternal and child factors, there was no significant difference between the timing of alcohol diagnosis relative to pregnancy and attendance outcomes. The population attributable fraction was higher in the Indigenous cohort than the non-Indigenous cohort (6.0% vs 1.3%).

CONCLUSIONS

Maternal alcohol use disorder was associated with a significantly increased odds of poor school attendance for non-Indigenous and Indigenous children. There was no significant difference between the timing of diagnoses and odds of poor school attendance. This suggests that the effect of maternal alcohol use disorder may not be driven by the neurodevelopmental effects of alcohol exposure in utero, but may be mediated through family or social factors for which we were unable to adjust.

Stratification strategy for evaluating the influence of diabetes complication severity index on the risk of hospitalization: a record linkage data in Western Australia

OBJECTIVE

This study aimed to develop a risk stratification strategy for evaluating the relationship between complications of diabetes and the risk of diabetic-related hospitalization to accurately classify diabetes severity.

METHODS

The study used administrative health records for 40,624 individuals with diabetes aged ≥18years in Western Australian. The adapted Diabetes Complication Severity Index (DCSI), socio-demographic and clinical characteristics were used in random effects negative binomial and threshold effect models to determine the optimal stratification strategy for diabetes severity based on the homogeneity of the risk of hospitalization in response to variation of the DCSI.

RESULTS

The optimal stratification of people with diabetes was specified by four sub-populations. The first sub-population was no complications with an inverse association with the risk of hospitalizations (coefficient-0.247, SE 0.03). Further three sub-populations with DCSI at one (coefficient 0.289, SE 0.01), two (coefficient 0.339, SE 0.01) and three or more (coefficient 0.381, SE 0.01) were used to accurately describe the impact of DCSI on the risk of hospitalization.

CONCLUSION

A stratification into four subpopulations based on the homogeneous impact of diabetes DCSI on the risk of hospitalization may be more suitable for evaluating health care interventions and planning health care provision.

Influence of exposure to perinatal risk factors and parental mental health related hospital admission on adolescent deliberate self-harm risk

Adolescent deliberate self-harm (DSH) has been found to be associated with a range of bio-psycho-social factors. Simultaneous investigations of these factors enable more robust estimation of the independent effect of a specific risk factor by adjusting for a more complete set of covariates. However, few studies have had the ability to examine all of these factors together. This study used the linkage of population-level de-identified data collections from government agencies to investigate a range of biological, psychological, and social risk factors and their effects on adolescent risk of DSH (with or without suicidal intent). The investigation was undertaken by progressively adjusting for plausible covariates, including fetal growth status and birth order, early familial social factors, parental hospital admissions due to psychiatric disorders or DSH, and parental all-cause death. Conditional logistic regression was used for data analysis. Children's psychiatric history was analysed to examine the extent to which it may account for the link between the risk factors and adolescent DSH risk. This study identified significant biological and perinatal social risk factors for adolescent DSH risk, including overdue birth, high birth order (≥2), single or teen/young motherhood, high neighbourhood socioeconomic disadvantage, and parental psychiatric and/or DSH-related hospital admissions. Further, parental psychiatric and/or DSH-related admissions, and children's psychiatric admissions in particular, largely attenuated the effects of the perinatal social risk factors but not the biological factors on adolescent DSH risk. These results highlight the importance of taking joint actions involving both health and social services in the prevention of adolescent DSH.

Maternal Alcohol Use Disorder and Risk of Child Contact with the Justice System in Western Australia: A Population Cohort Record Linkage Study

BACKGROUND

Early contact with the justice system is associated with a multitude of negative outcomes across the life course. This includes an increased risk of ongoing justice contact, social disadvantage and marginalization, and mental health and substance use issues. Children whose mothers have an alcohol use disorder may be at risk of early justice system contact, and we sought to quantify this relationship in a Western Australian cohort.

METHODS

This population cohort study made use of linked administrative data. Those in-scope for the study were women who had a birth recorded on the Midwives Notification System (1983 to 2007). The exposed cohort were mothers who had an alcohol-related diagnosis (ICD9/10), recorded on administrative data. This included mental and behavioral disorders which were alcohol related, diseases which could be entirely attributed to alcohol and other ICD alcohol codes. These women were considered to have an alcohol use disorder, which was a proxy for heavy drinking. The comparison cohort was frequency-matched sample with no alcohol-related diagnosis identified on administrative data sets.

RESULTS

After adjusting for potential confounders, children whose mothers had a maternal alcohol use disorder had a significantly increased odds of justice contact when compared to those whose mothers had no diagnosis (odds ratio [OR] = 1.79, 95% confidence interval [CI] = 1.60 to 1.99). Additional significant maternal factors associated with child justice contact included being Indigenous (OR = 5.14, 95% CI = 4.54 to 5.81), low maternal age, low socioeconomic status, being unmarried, and a history of a mental health problems. Significant child-level factors, which were associated with increased odds of justice contact, included being male, a mental health diagnosis, child protection contact, parity, and academic failure.

CONCLUSIONS

Children who were exposed to a maternal alcohol use disorder had significantly increased odds of contact with the justice system. Additional risk was associated with being Indigenous and with markers of social disadvantage. These results suggest that prevention and early intervention services should span across agencies in an effort to reduce risk.

Using record linkage to validate notification and laboratory data for a more accurate assessment of notifiable infectious diseases

BACKGROUND

Infectious disease burden is commonly assessed using notification data. Using retrospective record linkage in Western Australia, we described how well notification data captures laboratory detections of influenza, pertussis and invasive pneumococcal disease (IPD).

METHODS

We linked data from the Western Australian Notifiable Infectious Diseases Database (WANIDD) and the PathWest Laboratory Database (PathWest) pertaining to the Triple I birth cohort, born in Western Australia in 1996-2012. These were combined to calculate the number of unique cases captured in each dataset alone or in both datasets. To assess the impact of under-ascertainment, we compared incidence rates calculated using WANIDD data alone and using combined data.

RESULTS

Overall, there were 5550 influenza, 513 IPD (2001-2012) and 4434 pertussis cases (2000-2012). Approximately 2% of pertussis and IPD cases and 7% of influenza cases were solely recorded in PathWest. Notification of influenza and pertussis cases to WANIDD improved over time. Overall incidence rates of influenza in children aged <5 years using both datasets was 10% higher than using WANIDD data alone (IRR = 1.1, 95% CI = 1.1-1.2).

CONCLUSIONS

This is the first time WANIDD data have been validated against routinely collected laboratory data. We anticipated all cases would be captured in WANIDD but found additional laboratory-confirmed cases that were not notified. Studies investigating pathogen-specific infectious disease would benefit from using multiple data sources.

Incidence and Risk Factors for Deliberate Self-harm, Mental Illness, and Suicide Following Bariatric Surgery: A State-wide Population-based Linked-data Cohort Study

OBJECTIVE

Assess the incidence and determinants of hospitalization for deliberate self-harm and mental health disorders, and suicide after bariatric surgery.

BACKGROUND

Limited recent literature suggests an increase in deliberate self-harm following bariatric surgery.

METHODS

A state-wide, population-based, self-matched, longitudinal cohort study over a 5-year period between 2007 and 2011. Utilizing the Western Australian Department of Health Data Linkage Unit records, all patients undergoing bariatric surgery (n = 12062) in Western Australia were followed for an average 30.4 months preoperatively and 40.6 months postoperatively.

RESULTS

There were 110 patients (0.9%) hospitalized for deliberate self-harm, which was higher than the general population [incidence rate ratio (IRR) 1.47, 95% confidence interval (CI) 1.11-1.94, P = 0.005]. Compared with before surgery, there was no significant increase in deliberate self-harm hospitalizations (IRR 0.79, 95% CI 0.54-1.16; P = 0.206) and a reduction in overall mental illness related hospitalizations (IRR 0.76, 95% CI 0.63-0.91; P = 0.002) after surgery. Younger age, no private-health insurance cover, a history of hospitalizations due to depression before surgery, and gastrointestinal complications after surgery were predictors for deliberate self-harm hospitalizations after bariatric surgery. Three suicides occurred during the follow-up period, a rate comparable to the general population during the same time period (IRR 0.61, 95% CI 0.11-2.27, P = 0.444).

CONCLUSIONS

Hospitalization for deliberate self-harm in bariatric patients was more common than the general population, but an increased incidence of deliberate self-harm after bariatric surgery was not observed. Hospitalization for depression before surgery and major postoperative gastrointestinal complications after bariatric surgery are potentially modifiable risk factors for deliberate self-harm after bariatric surgery.

Geographic distribution of burn in an Australian setting

OBJECTIVE

To investigate the geographic distribution and temporal trends of burn admissions in an Australian setting.

METHODS

Health administrative data of all persons hospitalised for a first burn in Western Australia for the period 2000-2012 were used. Crude and standardised incident rates were generated for each region. Maps of crude rates were generated for state regions and postcode-suburbs of Perth, the capital city. Standardised incidence rates were generated for Western Australia, total and regions, and for sub-cohorts defined by age (<20years; ≥20 years), TBSA burn severity and major causes of burns (fire, scalds and contact). Negative binomial regression was used to examine temporal changes and generate incidence rate ratios (IRR) with 95% confidence intervals (CI).

RESULTS

Perth had the lowest burn admission rate per population; clusters of suburbs of lower social advantage and higher immigrant settlement were identified as being at high risk. While the highest observed admission rates were found in Kimberley and Goldfields (remote) regions, after adjustment for the regional demographic structures, the Wheatbelt and Mid-West (rural) regions were found to have the highest adjusted rates of burn admissions. Significant annual declines in admission rates were found for the Kimberley, Pilbara and Goldfields (remote regions); however, stable admission rates were identified for all other regions.

CONCLUSIONS

The Mid-West and Wheatbelt rural regions were found to have the highest risk of burn admissions raising concerns about farming-related injury. Safety awareness and burn prevention strategies need to be continued, with specific attention to these high risk areas, to reduce burn admissions in Western Australia.

Maternal alcohol disorders and school achievement: a population cohort record linkage study in Western Australia

OBJECTIVE

Maternal alcohol use disorder is a risk factor for a range of developmental outcomes in children. This study examines school achievement in children of Indigenous and non-Indigenous mothers with an alcohol-related diagnosis.

DESIGN, SETTING AND PARTICIPANTS

This is a Western Australian population cohort study of mothers with a record of an alcohol-related diagnosis classified by the International Classification of Diseases Revisions 9/10 codes as recorded on administrative databases, and of their offspring born between 1989 and 2007 (n=18 486 exposed children), with a frequency matched comparison cohort of mothers with no record of alcohol diagnosis and their offspring (n=48 262 comparison children).

OUTCOMES

Records were linked with school achievement data for numeracy and literacy from Years 3, 5, 7 and 9 (age range: ~8-14 years) based on statewide and national testing. Mixed multivariate models with a random intercept per child were used to assess the relationship between exposure and the timing of exposure with failure to meet minimum standardised benchmarks.

RESULTS

Academic achievement was lower in all testing domains (reading, writing, spelling and numeracy) among children of mothers with an alcohol diagnosis and persisted across all year groups examined. The highest ORs at Year 9 for non-Indigenous children were in reading (adjusted OR (aOR) 1.6, 95% CI 1.4 to 1.8) and in writing for Indigenous children (aOR 2.0, 95% CI 1.8 to 2.3).

CONCLUSION

Children of mothers with alcohol use disorders are at risk of not meeting minimum educational benchmarks in numeracy and literacy, with the risk highest among Indigenous children.

The impact of child maltreatment on the risk of deliberate self-harm among adolescents: A population-wide cohort study using linked administrative records

Adolescents exposed to maltreatment have an elevated risk of deliberate self-harm (DSH). The aim of this study was to investigate longitudinally the effects of the number, timing, and type of maltreatment allegations on adolescent risk of having a DSH-related hospital admission, using linked data in Western Australia. A total of 351,372 children born between 1986 and 2000 were followed from birth up to the year 2010. Cox regression models were utilized, while controlling for a range of psychosocial covariates. Compared to children without allegations of maltreatment, children with unsubstantiated allegations only (aHR=1.04, 95%CI: 1.00-1.08, p<.01) and children with a substantiated allegation (aHR=1.10, 95%CI: 1.06-1.15, p<.001) all had significantly increased risk of DSH in adolescence. Among children with a substantiated allegation of maltreatment, the greater the number of allegations, the longer the exposure to maltreatment, and the more types of maltreatment experienced by a child, the higher the child's risk of DSH. However, this dose-response pattern was not found among children with unsubstantiated allegations only. This study calls for the early identification of children who are vulnerable to maltreatment, the better identification of the duration and severity of maltreatment experiences, and the provision of continued care and support, to reduce the child's DSH risk in adolescence.