Sean M. Randall

Privacy-preserving record linkage on large real world datasets.

Record linkage typically involves the use of dedicated linkage units who are supplied with personally identifying information to determine individuals from within and across datasets. The personally identifying information supplied to linkage units is separated from clinical information prior to release by data custodians. While this substantially reduces the risk of disclosure of sensitive information, some residual risks still exist and remain a concern for some custodians. In this paper we trial a method of record linkage which reduces privacy risk still further on large real world administrative data. The method uses encrypted personal identifying information (bloom filters) in a probability-based linkage framework. The privacy preserving linkage method was tested on ten years of New South Wales (NSW) and Western Australian (WA) hospital admissions data, comprising in total over 26 million records. No difference in linkage quality was found when the results were compared to traditional probabilistic methods using full unencrypted personal identifiers. This presents as a possible means of reducing privacy risks related to record linkage in population level research studies. It is hoped that through adaptations of this method or similar privacy preserving methods, risks related to information disclosure can be reduced so that the benefits of linked research taking place can be fully realised.

Data linkage infrastructure for cross-jurisdictional health-related research in Australia

BackgroundThe Centre for Data Linkage (CDL) has been established to enable national and cross-jurisdictional health-related research in Australia. It has been funded through the Population Health Research Network (PHRN), a national initiative established under the National Collaborative Research Infrastructure Strategy (NCRIS). This paper describes the development of the processes and methodology required to create cross-jurisdictional research infrastructure and enable aggregation of State and Territory linkages into a single linkage “map”.MethodsThe CDL has implemented a linkage model which incorporates best practice in data linkage and adheres to data integration principles set down by the Australian Government. Working closely with data custodians and State-based data linkage facilities, the CDL has designed and implemented a linkage system to enable research at national or cross-jurisdictional level. A secure operational environment has also been established with strong governance arrangements to maximise privacy and the confidentiality of data.ResultsThe development and implementation of a cross-jurisdictional linkage model overcomes a number of challenges associated with the federated nature of health data collections in Australia. The infrastructure expands Australia’s data linkage capability and provides opportunities for population-level research. The CDL linkage model, infrastructure architecture and governance arrangements are presented. The quality and capability of the new infrastructure is demonstrated through the conduct of data linkage for the first PHRN Proof of Concept Collaboration project, where more than 25 million records were successfully linked to a very high quality.ConclusionsThis infrastructure provides researchers and policy-makers with the ability to undertake linkage-based research that extends across jurisdictional boundaries. It represents an advance in Australia’s national data linkage capabilities and sets the scene for stronger government-research collaboration.

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.

The effect of data cleaning on record linkage quality

BackgroundWithin the field of record linkage, numerous data cleaning and standardisation techniques are employed to ensure the highest quality of links. While these facilities are common in record linkage software packages and are regularly deployed across record linkage units, little work has been published demonstrating the impact of data cleaning on linkage quality.MethodsA range of cleaning techniques was applied to both a synthetically generated dataset and a large administrative dataset previously linked to a high standard. The effect of these changes on linkage quality was investigated using pairwise F-measure to determine quality.ResultsData cleaning made little difference to the overall linkage quality, with heavy cleaning leading to a decrease in quality. Further examination showed that decreases in linkage quality were due to cleaning techniques typically reducing the variability – although correct records were now more likely to match, incorrect records were also more likely to match, and these incorrect matches outweighed the correct matches, reducing quality overall.ConclusionsData cleaning techniques have minimal effect on linkage quality. Care should be taken during the data cleaning process.

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.

Perils of police action: a cautionary tale from US data sets

Objective To count and characterise injuries resulting from legal intervention by US law enforcement personnel and injury ratios per 10 000 arrests or police stops, thus expanding discussion of excessive force by police beyond fatalities. Design Ecological. Population Those injured during US legal police intervention as recorded in 2012 Vital Statistics mortality census, 2012 Healthcare Cost and Utilization Project nationwide inpatient and emergency department samples, and two 2015 newspaper censuses of deaths. Exposure 2012 and 2014 arrests from Federal Bureau of Investigation data adjusted for non-reporting jurisdictions; street stops and traffic stops that involved vehicle or occupant searches, without arrest, from the 2011 Police Public Contact Survey (PPCS), with the percentage breakdown by race computed from pooled 2005, 2008 and 2011 PPCS surveys due to small case counts. Results US police killed or injured an estimated 55 400 people in 2012 (95% CI 47 050 to 63 740 for cases coded as police involved). Blacks, Native Americans and Hispanics had higher stop/arrest rates per 10 000 population than white non-Hispanics and Asians. On average, an estimated 1 in 291 stops/arrests resulted in hospital-treated injury or death of a suspect or bystander. Ratios of admitted and fatal injury due to legal police intervention per 10 000 stops/arrests did not differ significantly between racial/ethnic groups. Ratios rose with age, and were higher for men than women. Conclusions Healthcare administrative data sets can inform public debate about injuries resulting from legal police intervention. Excess per capita death rates among blacks and youth at police hands are reflections of excess exposure. International Classification of Diseases legal intervention coding needs revision.

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.

Long-term Effects of Pediatric Burns on the Circulatory System.

BACKGROUND: The systemic responses to burns (in particular, elevated levels of catecholamines and stress hormones) have been shown to have an impact on cardiac function for at least 3 years in children with burns. However, it is not clear if these changes lead to long-term effects on the heart. The aim of this study was to assess whether pediatric burn injury is associated with increased long-term hospital use for circulatory diseases. METHODS: A population-based longitudinal study was undertaken using linked hospital and death data from Western Australia for children younger than 15 years when hospitalized for a first burn injury (n = 10 436) in 1980–2012 and a frequency matched noninjury comparison cohort, randomly selected from Western Australia’s birth registrations (n = 40 819). Crude admission rates and cumulative length of stay for circulatory diseases were calculated. Negative binomial and Cox proportional hazards regression modeling were used to generate incidence rate ratios and hazard ratios, respectively. RESULTS: After adjustment for demographic factors and preexisting health status, the burn cohort had 1.33 (incidence rate ratio) times (95% confidence interval [CI]: 1.08–1.64) as many circulatory system hospitalizations, 2.26 times the number of days in hospital with a diagnosis of a circulatory disease (2.26, 95% CI: 1.06–4.81), and were at a higher risk of incident admissions (hazard ratio 1.22, 95% CI: 1.03–1.46), compared with the uninjured cohort. CONCLUSIONS: Children who sustain burn injury experience elevated hospital admission rates and increased length of hospital stay for diseases of the circulatory system for a prolonged period of time after burn discharge.

Long term mortality in a population-based cohort of adolescents, and young and middle-aged adults with burn injury in Western Australia: A 33-year study

BACKGROUND Advances in the treatment and management of burn patients over the past decades have resulted in a decline of in-hospital mortality rates. Current estimates of burn-related mortality are usually in the context of deaths occurring during the admission or within a short time period after the incident burn. Limited data are available that examine long term mortality after burn injury. This study aimed to assess the impact of burn injury on long-term mortality and quantify any increased risk of death attributable to burn injury. METHODS A population-based cohort study of persons 15-44 years of age hospitalised for burn injury (n=14,559) in Western Australia (1980-2012) and a matched non-injured comparison group (n=56,822) using linked health administrative data was used. Hospital morbidity and death data were obtained from the Western Australian Hospital Morbidity Data System and Death Register. De-identified extraction of all linked hospital morbidity and death records for the period 1980-2012 were provided by the Western Australian Data Linkage System. Survival analysis was conducted using the Kaplan-Meier method and Cox proportional hazards modelling. RESULTS The adjusted all-cause Mortality Rate Ratio (MRR) for burn injury was 1.8 (95%CI: 1.7-2.0); those with burn injury had a 1.8 times greater rate of mortality than those with no injury. The index burn injury was estimated to account for 44% of all recorded deaths in the burn injury cohort during the study period after discharge. Increased risk of mortality was observed for both severe (MRR, 95%CI: 1.9, 1.3-2.9) and minor (MRR, 95%CI: 2.5, 2.2-3.0) burns. CONCLUSIONS An increased risk of long-term all-cause mortality is associated with both minor and severe burn injury. Estimates of total mortality burden based on the early in-patient period alone, significantly underestimates the true burden of burn injury in adolescents, and young and middle aged adults. These results have significant implications for burn injury prevention.

Long-term musculoskeletal morbidity after adult burn injury: a population-based cohort study

Objective To investigate if adults who are hospitalised for a burn injury have increased long-term hospital use for musculoskeletal diseases. Design A population-based retrospective cohort study using linked administrative health data from the Western Australian Data Linkage System. Subjects Records of 17 753 persons aged at least 20 years when hospitalised for a first burn injury in Western Australia during the period 1980–2012, and 70 758 persons who were age and gender-frequency matched with no injury admissions randomly selected from Western Australias electoral roll. Main outcome measures Admission rates and cumulative length of stay for musculoskeletal diseases. Negative binomial and Cox proportional hazards regression modelling were used to generate incidence rate ratios (IRR) and HRs with 95% CIs, respectively. Results After adjustment for pre-existing health status and demographic characteristics, the burn cohort had almost twice the hospitalisation rate for a musculoskeletal condition (IRR, 95% CI 1.98, 1.86 to 2.10), and spent 3.70 times as long in hospital with a musculoskeletal diagnosis (95% CI 3.10 to 4.42) over the 33-year period, than the uninjured comparison cohort. Adjusted survival analyses of incident post-burn musculoskeletal disease admissions found significant increases for the 15-year post burn discharge period (0–6 months: HR, 95% CI 2.51, 2.04 to 3.11; 6 months–2 years: HR, 95% CI 1.77, 1.53 to 2.05; 2–15 years: HR, 95% CI 1.32, 1.23 to 1.42). Incident admission rates were significantly elevated for 20 years post-burn for minor and severe burn injury for a range of musculoskeletal diseases that included arthropathies, dorsopathies, osteopathies and soft tissue disorders. Conclusions Minor and severe burn injuries were associated with significantly increased post-burn incident admission rates, long-term hospital use and prolonged length of stay for a range of musculoskeletal diseases. Further research is required that facilitates identification of at-risk patients and appropriate treatment pathways, to reduce the long-term morbidity associated with burns.