Janine M. Duke

Cohort Profile: The Hunter Community Study

In almost every country, the proportion of people aged 460 years is growing faster than any other age group and is expected to reach 2 billion worldwide by 2050. Internationally and nationally, considerable efforts are being made to promote active ageing. However, Australia lacks the kind of comprehensive longitudinal research underway in Europe and North America. Although Australia does have a number of longitudinal studies designed to address various issues of health and ageing among older adults, only a few of these studies include a broad and comprehensive range of physical and biological measures. The Hunter Community Study (HCS) is a collaborative study between the University of Newcastle’s School of Medicine and Public Health and the Hunter New England Area Health Service. It is a multi disciplinary initiative that was established to fill some existing gaps in ageing research in Australia and is unique in that it has collected detailed information across all six key policy themes as identified in the Framework for an Australian Ageing Research Agenda. What does the study cover?

A 26-Year Population-Based Study of Burn Injury Hospital Admissions in Western Australia

The aim of the study was to use state-wide health administrative data to assess the incidence, temporal trends, and external cause of burn injury-related hospital admissions and mortality in Western Australia from 1983 to 2008. Linked hospital morbidity and death data for all persons hospitalized with an index burn injury in Western Australia for the period 1983–2008 were identified. Annual age-specific incidence and age standardized rates were estimated. Poisson regression analyses were used to estimate temporal trends in hospital admissions and mortality. Zero-truncated negative binomial regression analysis was used to identify factors associated with hospital length of stay. From 1983 to 2008, there were 23,450 hospitalizations for an index burn injury. Hospital admission rates declined by an average annual rate of 2% (incidence rate ratio [IRR], 95% confidence interval [CI] = 0.983, 0.981–0.984), and burn-related mortality declined by an average annual rate of 2% (IRR, 95% CI = 0.98, 0.96–1.01). Aboriginal people while having significantly higher hospitalization rates than non-Aboriginal people experienced a greater 26-year decline in hospitalizations of 58% (IRR, 95% CI = 0.42, 0.37–0.48) compared with 32% (IRR, 95% CI = 0.68, 0.65–0.71) for non-Aboriginal people. Children younger than 5 years, 20- to 24-year-old men, and adults older than 65 years remain at high risk for burn injury, and males continue to be hospitalized twice as frequently as females. The results demonstrate declines in burn injury hospitalizations and mortality in both Aboriginal and non-Aboriginal populations. Continued research is required of the impacts of medical interventions and the burn pathway of identified high-risk populations.

Psychoactive Medications and Crash Involvement Requiring Hospitalization for Older Drivers: A Population-Based Study

OBJECTIVES: To determine the association between psychoactive medications and crash risk in drivers aged 60 and older.

A study of burn hospitalizations for children younger than 5 years of age: 1983-2008

OBJECTIVE: Burn injury is a leading cause of emergency department visits and hospitalizations for young children. We aimed to use statewide linked health administrative data to evaluate the incidence, temporal trends, and cause of burn injuries for children younger than 5 years hospitalized for burn injuries in Western Australia for the period 1983–2008. METHODS: Epidemiologic analysis of linked hospital morbidity and death data of children younger than 5 years hospitalized with an index burn injury in Western Australia for the period 1983–2008. Poisson regression analyses were used to estimate temporal trends in hospital admissions and the external cause of the burn injury. RESULTS: From 1983 to 2008, there were 5398 hospitalizations for an index burn injury and 3 burn-related deaths. Hospital admission rates declined by an average annual rate of 2.3% (incidence rate ratio: 0.977 [95% confidence interval: 0.974–0.981]). More than half of the admissions were for scald burns. Hospitalizations declined for injury caused by scald, flame, contact, and electrical burns; however, the number of hospital admissions increased for chemical burns during the study period. CONCLUSIONS: The burn-injury hospitalizations reported in this study were preventable. Most burns occurred in the home and resulted from exposure to a household hazard. Further effort needs to be devoted to burn prevention and safety strategies, particularly in relation to scalds, to further reduce the incidence of burn injury in young children.

Severe psychiatric disorders in mid-life and risk of dementia in late-life (age 65-84 years): A population based case-control study

Objective: To examine the association of mid-life exposure to several psychiatric disorders with the development of late-life dementia. Methods: A matched case-control study using Western Australian state-wide hospital inpatient, outpatient mental health and emergency records linked to death records. Incident dementia cases (2000-2009) aged 65 to 84 years were sex- and age-matched to an electoral roll control. Records as far back as 1970 were used to assess exposure to medical risk factors before age 65 years. Candidate psychiatric risk factors were required to be present at least 10 years before dementia onset to ensure direction of potential causality. Odds ratios were estimated using conditional logistic regression. Results: 13, 568 dementia cases (median age 78.7 years, 43.4% male) were matched to a control. Depression, bipolar disorder, schizophrenia, anxiety disorder and alcohol dependence were found to be significant and independent risk factors for late-life dementia after adjusting for diabetes, heart disease, cerebrovascular disease and smoking risk factors. The effect of a history of depression, schizophrenia and alcohol dependency on dementia risk varied with age, being strongest for earlier onset late-life dementia and waning at older ages. Conclusion: Severe depression, anxiety disorder, bipolar disorder, schizophrenia and alcoholic dependency disorder treated by specialists in psychiatric facilities in mid-life are important risk factors for late-life dementia. These psychiatric conditions need to be considered in future studies of the risk and prevention of late-life dementia.

Mortality After Burn Injury in Children: A 33-year Population-Based Study

OBJECTIVE: To assess the impact of burn injury sustained during childhood on long-term mortality and to quantify any increased risk of death attributable to burn injury. METHODS: A population-based cohort study of children younger than 15 years hospitalized for burn injury in Western Australia (1980–2012) and a matched noninjured comparison group. Deidentified extraction of linked hospital morbidity and death records for the period 1980–2012 were provided by the Western Australian Data Linkage System. An inception cohort (1980–2012) of burn cases younger than 15 years of age when hospitalized for a first burn injury (n = 10 426) and a frequency matched noninjured comparison cohort (n = 40 818) were identified. Survival analysis was conducted by using the Kaplan-Meier method and Cox proportional hazards regression. Mortality rate ratios and attributable risk percent adjusted for sociodemographic and preexisting heath factors were generated. RESULTS: The median follow-up time for the pediatric burn cohort was 18.1 years after discharge. The adjusted all-cause mortality rate ratios for burn injury was 1.6 (95% confidence interval: 1.3–2.0); children with burn injury had a 1.6 times greater rate of mortality than those with no injury. The index burn injury was estimated to account for 38% (attributable risk percent) of all recorded deaths in the burn injury cohort during the study period. CONCLUSIONS: Burn injury sustained by children is associated with an increased risk of long-term all-cause mortality. Estimates of the total mortality burden based on in-hospital deaths alone underestimates the true burden from burn injury.

Long-term mortality among older adults with burn injury: a population-based study in Australia

Abstract Objective To assess if burn injury in older adults is associated with changes in long-term all-cause mortality and to estimate the increased risk of death attributable to burn injury. Methods We conducted a population-based matched longitudinal study – based on administrative data from Western Australia’s hospital morbidity data system and death register. A cohort of 6014 individuals who were aged at least 45 years when hospitalized for a first burn injury in 1980–2012 was identified. A non-injury comparison cohort, randomly selected from Western Australia’s electoral roll (n = 25 759), was matched to the patients. We used Kaplan–Meier plots and Cox proportional hazards regression to analyse the data and generated mortality rate ratios and attributable risk percentages. Findings For those hospitalized with burns, 180 (3%) died in hospital and 2498 (42%) died after discharge. Individuals with burn injury had a 1.4-fold greater mortality rate than those with no injury (95% confidence interval, CI: 1.3–1.5). In this cohort, the long-term mortality attributable to burn injury was 29%. Mortality risk was increased by both severe and minor burns, with adjusted mortality rate ratios of 1.3 (95% CI: 1.1–1.9) and 2.1 (95% CI: 1.9–2.3), respectively. Conclusion Burn injury is associated with increased long-term mortality. In our study population, sole reliance on data on in-hospital deaths would lead to an underestimate of the true mortality burden associated with burn injury.

Understanding the long-term impacts of burn on the cardiovascular system

BACKGROUND Whilest the most obvious impact of burn is on the skin, systemic responses also occur after burn that lead to wide-spread changes to the body, including the heart. The aim of this study was to assess if burn in mid-aged and older adults is associated with increased long-term admissions and death due to diseases of the circulatory system. METHODS A population-based longitudinal study using linked hospital morbidity and death data from Western Australia was undertaken of adults aged at least 45 years when hospitalized for a first burn (n=6004) in 1980-2012 and a frequency matched non-injury comparison cohort, randomly selected from Western Australias electoral roll (n=22,673). Crude admission rates and cumulative length of stay for circulatory diseases were calculated. Negative binomial and Cox proportional hazards regression modelling were used to generate incidence rate ratios (IRR) and hazard ratios (HR), respectively. HR was used as a measure of the mortality rate ratio (MRR). RESULTS After adjustment for demographic factors and pre-existing health status, the burn cohort had 1.46 times (95% confidence interval (CI): 1.36-1.56) as many admissions and almost three times the number of days in hospital with a circulatory system diagnosis (IRR, 95%CI: 2.90, 2.60-3.25) than the uninjured cohort for circulatory diseases. The burn cohort had higher admission rates for ischaemic heart disease (IRR, 95%CI: 1.21, 1.07-1.36), heart failure (IRR, 95%CI: 2.29, 1.85-2.82) and cerebrovascular disease (IRR, 95%CI: 1.57, 1.33-1.84). The burn cohort was found to have increased long-term mortality caused by circulatory system diseases (MRR, 95%CI: 1.11, 1.02-1.20). CONCLUSIONS Findings of increased hospital admission rates, prolonged length of hospital stay and increased long-term mortality related to circulatory system diseases in the burn cohort provide evidence to support that burn has long-lasting systemic impacts on the heart and circulation.

Developing a burn injury severity score (BISS): Adding age and total body surface area burned to the injury severity score (ISS) improves mortality concordance

BACKGROUND There is limited research validating the injury severity score (ISS) in burns. We examined the concordance of ISS with burn mortality. We hypothesized that combining age and total body surface area (TBSA) burned to the ISS gives a more accurate mortality risk estimate. METHODS Data from the Royal Perth Hospital Trauma Registry and the Royal Perth Hospital Burns Minimum Data Set were linked. Area under the receiver operating characteristic curve (AUC) measured concordance of ISS with mortality. Using logistic regression models with death as the dependent variable we developed a burn-specific injury severity score (BISS). RESULTS There were 1344 burns with 24 (1.8%) deaths, median TBSA 5% (IQR 2-10), and median age 36 years (IQR 23-50). The results show ISS is a good predictor of death for burns when ISS≤15 (OR 1.29, p=0.02), but not for ISS>15 (ISS 16-24: OR 1.09, p=0.81; ISS 25-49: OR 0.81, p=0.19). Comparing the AUCs adjusted for age, gender and cause, ISS of 84% (95% CI 82-85%) and BISS of 95% (95% CI 92-98%), demonstrated superior performance of BISS as a mortality predictor for burns. CONCLUSION ISS is a poor predictor of death in severe burns. The BISS combines ISS with age and TBSA and performs significantly better than the ISS.

Burn injury, gender and cancer risk: population-based cohort study using data from Scotland and Western Australia

Objective To investigate the risk of cancer and potential gender effects in persons hospitalised with burn injury. Design Population-based retrospective cohort study using record-linkage systems in Scotland and Western Australia. Participants Records of 37 890 and 23 450 persons admitted with a burn injury in Scotland and Western Australia, respectively, from 1983 to 2008. Deidentified extraction of all linked hospital morbidity records, mortality and cancer records were provided by the Information Service Division Scotland and the Western Australian Data Linkage Service. Main outcome measures Total and gender-specific number of observed and expected cases of total (‘all sites’) and site-specific cancers and standardised incidence ratios (SIRs). Results From 1983 to 2008, for female burn survivors, there was a greater number of observed versus expected notifications of total cancer with 1011 (SIR, 95% CI 1.3, 1.2 to 1.4) and 244 (SIR, 95% CI 1.12, 1.05 to 1.30), respectively, for Scotland and Western Australia. No statistically significant difference in total cancer risk was found for males. Significant excesses in observed cancers among burn survivors (combined gender) in Scotland and Western Australian were found for buccal cavity, liver, larynx and respiratory tract and for cancers of the female genital tract. Conclusions Results from the Scotland data confirmed the increased risk of total (‘all sites’) cancer previously observed among female burn survivors in Western Australia. The gender dimorphism observed in this study may be related to the role of gender in the immune response to burn injury. More research is required to understand the underlying mechanism(s) that may link burn injury with an increased risk of some cancers.