Risk of persistent and recurrent cervical neoplasia following incidentally detected adenocarcinoma in situ.

BACKGROUND: Adenocarcinoma in situ of the uterine cervix is a precursor to cervical adenocarcinoma and may coexist with both adenocarcinoma and high-grade squamous dysplasia (cervical intraepithelial neoplasia 2 and 3). Up to 60% of adenocarcinoma in situ lesions are detected incidentally following excisional biopsies performed for the treatment of cervical intraepithelial neoplasia 2/3. To date there are no data regarding risk factors for persisting or progressive cervical neoplasia in these patients. OBJECTIVE: We sought to investigate patient outcomes following incidentally detected cervical adenocarcinoma in situ after loop electrosurgical excision procedure or cold knife cone biopsy performed for the treatment of high-grade cervical intraepithelial neoplasia. STUDY DESIGN: We conducted a retrospective, population-based cohort study of Western Australian patients with an incidental diagnosis of adenocarcinoma in situ from 2001 through 2012. Primary outcomes were persistent or recurrent cervical intraepithelial neoplasia 2/3 and or adenocarcinoma in situ, and invasive adenocarcinoma during follow-up (<12 months) and surveillance (≥12 months) periods. RESULTS: The cohort comprised 298 patients, with 228 (76.5%) treated initially by loop electrosurgical excision procedure and 70 (23.5%) treated by cold knife cone biopsy. The mean age was 31.2 (range 18-68) years and the median length of follow-up was 2.4 (range 0.3-12.2) years. Overall, 11 (3.7%) patients had cervical intraepithelial neoplasia 2/3, 23 (7.7%) had adenocarcinoma in situ, and 3 (1.0%) had adenocarcinoma diagnosed during the follow-up and surveillance periods. Age >30 years, pure adenocarcinoma in situ lesions, and larger lesions (>8 mm) were associated with a greater risk of disease persistence or recurrence. CONCLUSION: Following the incidental detection of adenocarcinoma in situ, age >30 years, pure adenocarcinoma in situ lesions, and lesions >8 mm were significantly associated with disease persistence/recurrence. In younger women, incidentally detected adenocarcinoma in situ that coexists with cervical intraepithelial neoplasia 2/3 and is <8 mm extent with clear margins may not require reexcision.

Estimating parameters for probabilistic linkage of privacy-preserved datasets.

BACKGROUND: Probabilistic record linkage is a process used to bring together person-based records from within the same dataset (de-duplication) or from disparate datasets using pairwise comparisons and matching probabilities. The linkage strategy and associated match probabilities are often estimated through investigations into data quality and manual inspection. However, as privacy-preserved datasets comprise encrypted data, such methods are not possible. In this paper, we present a method for estimating the probabilities and threshold values for probabilistic privacy-preserved record linkage using Bloom filters. METHODS: Our method was tested through a simulation study using synthetic data, followed by an application using real-world administrative data. Synthetic datasets were generated with error rates from zero to 20% error. Our method was used to estimate parameters (probabilities and thresholds) for de-duplication linkages. Linkage quality was determined by F-measure. Each dataset was privacy-preserved using separate Bloom filters for each field. Match probabilities were estimated using the expectation-maximisation (EM) algorithm on the privacy-preserved data. Threshold cut-off values were determined by an extension to the EM algorithm allowing linkage quality to be estimated for each possible threshold. De-duplication linkages of each privacy-preserved dataset were performed using both estimated and calculated probabilities. Linkage quality using the F-measure at the estimated threshold values was also compared to the highest F-measure. Three large administrative datasets were used to demonstrate the applicability of the probability and threshold estimation technique on real-world data. RESULTS: Linkage of the synthetic datasets using the estimated probabilities produced an F-measure that was comparable to the F-measure using calculated probabilities, even with up to 20% error. Linkage of the administrative datasets using estimated probabilities produced an F-measure that was higher than the F-measure using calculated probabilities. Further, the threshold estimation yielded results for F-measure that were only slightly below the highest possible for those probabilities. CONCLUSIONS: The method appears highly accurate across a spectrum of datasets with varying degrees of error. As there are few alternatives for parameter estimation, the approach is a major step towards providing a complete operational approach for probabilistic linkage of privacy-preserved datasets.

The Association of Community-Based Palliative Care With Reduced Emergency Department Visits in the Last Year of Life Varies by Patient Factors.

STUDY OBJECTIVE: Palliative care has been shown to reduce end-of-life emergency department (ED) use. Our objective was to determine how the association of community-based palliative care with reduced ED visits in the last year of life varied by patient factors. METHODS: This was a retrospective cohort study of 11,875 decedents who died with neoplasms, heart failure, renal failure, chronic obstructive pulmonary disease, or liver failure in Western Australia in 2009 to 2010. Outcome measures were adjusted hazard ratios (HRs) and daily (hazard) rates of ED visits. RESULTS: The adjusted average rate of ED visits for the cohort was reduced 50% (HR 0.50; 95% confidence interval [CI] 0.47 to 0.53) during periods of receipt of community-based palliative care. This relative reduction in ED visits varied by patient factors, ranging from 43% (HR 0.57; 95% CI 0.45 to 0.74) for decedents aged 60 years and younger up to 71% (HR 0.29; 95% CI 0.18 to 0.46) for people aged 90 years and older. Decedents living in the most disadvantaged areas had a 44% (HR 0.56; 95% CI 0.44 to 0.72) reduction in ED visits when receiving community-based palliative care compared with a 60% (HR 0.40; 95% CI 0.31 to 0.53) reduction for decedents who lived in the least disadvantaged areas and received this care. The ED visit rates while patients were receiving palliative care also varied by ED visit history, partner status, and region of residence. CONCLUSION: Receipt of community-based palliative care in the last year of life was associated with a reduced rate of ED visits. The magnitude of this association was modified by patient health, as well as social and demographic factors.

Risk of persistent or recurrent neoplasia in conservatively treated women with cervical adenocarcinoma in situ with negative histological margins.

INTRODUCTION: Conservative treatments including cold knife cone biopsy (CKC) or loop electrosurgical excision procedure (LEEP) are fertility-preserving alternatives to hysterectomy. The risks of persistent cervical neoplasia in women with negative surgical margins following conservative treatment of adenocarcinoma-in-situ (AIS) are uncertain. This study aims to investigate the risk of persistent or recurrent cervical neoplasia [AIS, adenocarcinoma and/or high-grade cervical squamous intraepithelial neoplasia (CIN)] and compliance with follow-up recommendations in conservatively treated women with AIS and negative histopathological margins. MATERIAL AND METHODS: A retrospective, population-based study of Western Australian women treated by CKC or LEEP for AIS between 2001 and 2012. Histopathology reports were reviewed for demographic information, treatment procedures and clinicopathological factors. Primary outcomes were the diagnosis of cervical neoplasia during follow-up (defined as <12 months) and surveillance (≥12 months) periods. RESULTS: The cohort comprised 360 women, with 175 (48.6%) initially treated by CKC and 185 (51.4%) treated by LEEP. The median patient age at time of excisional treatment was 30.0 years (range 18-64 years) and the median follow-up time was 3.9 years (range six months to 12.2 years). During the follow-up and surveillance periods, seven (1.9%) women were diagnosed with CIN 2/3, 10 (2.8%) with AIS, and one (0.3%) with cervical adenocarcinoma, despite their initial excision specimens having negative histological margins. CONCLUSION: In this study, there was a low but significant risk of persistent or recurrent cervical neoplasia in women who had initial conservative management of AIS with negative histopathological margins.

Red blood cell transfusion is associated with further bleeding and fresh-frozen plasma with mortality in nonvariceal upper gastrointestinal bleeding.

BACKGROUND: Blood products are commonly transfused for patients with nonvariceal upper gastrointestinal bleeding (NVUGIB). While concerns exist about further bleeding and mortality in subsets of patients receiving red blood cell (RBC) transfusion, the impact of non-RBC blood products has not previously been systematically investigated. The aim of the study was to investigate the associations between blood products transfusion, further bleeding, and mortality after acute NVUGIB. STUDY DESIGN AND METHODS: A retrospective cohort study examined further bleeding and 30-day and 1-year mortality in adult patients who underwent gastroscopy for suspected acute NVUGIB between 2008 and 2010 in three tertiary hospitals in Western Australia. Survival analysis was performed. RESULTS: A total of 2228 adults (63% male) with 2360 hospital admissions for NVUGIB met the inclusion criteria. Median age at presentation was 70 years (range, 19-99 years). Thirty-day mortality was 4.9% and 1-year mortality was 13.9%. Transfusion of 4 or more units of RBCs was associated with greater than 10 times the odds of further bleeding in patients with a hemoglobin level of more than 90 g/L (odds ratio, 11.9; 95% confidence interval [CI], 3.1-45.7; p ≤ 0.001), but was not associated with mortality. Administration of 5 or more units of fresh-frozen plasma (FFP) was associated with increased 30-day (hazard ratio, 2.8; 95% CI, 1.3-5.9; p = 0.008) and 1-year (hazard ratio, 2.6; 95% CI, 1.3-5.0; p = 0.005) mortality after adjusting for coagulopathy, comorbidity, Rockall score, and other covariates. CONCLUSION: In this large, multicenter study of NVUGIB, RBC transfusion was associated with further bleeding but not mortality, while FFP transfusion was associated with increased mortality in a subset of patients.

Spontaneous regression of CIN2 in women aged 18-24 years: a retrospective study of a state-wide population in Western Australia.

INTRODUCTION: CIN2 has a high rate of spontaneous regression in young women and may be managed conservatively in appropriately selected patients. This study aimed to investigate health outcomes in women aged 18-24 years with biopsy-confirmed CIN2. MATERIAL AND METHODS: A retrospective cohort study of Western Australian women aged 18-24 years diagnosed with CIN2 on cervical biopsy from 1 January 2001 to 31 December 2010. Women who had not received treatment at ≥4 months following CIN2 diagnosis were classified as managed 'conservatively'. Subsequent cervical cytology and/or biopsy test results were used to report lesion regression (absence of dysplasia or an epithelial lesion of lower grade than CIN2) and disease persistence (CIN2, CIN3 or ACIS). RESULTS: Follow-up data were available for 2417 women of whom 924 (38.2%) were 'conservatively' managed. In all, 152 (16.4%) conservatively managed women had a lesion more severe than CIN2 detected within 24 months of initial diagnosis, of which 144 were CIN3 and eight were ACIS. There was no statistically significant association between rates of regression and patient age, Socio-economic Indexes for Areas or Accessibility/Remoteness Index of Australia indices. The 2-year regression rate for CIN2 was estimated to be 59.5% (95%CI 0.5-0.6) in this cohort of women. CONCLUSION: In conservatively managed young women with CIN2 there was a high rate of spontaneous disease regression. Thus, excisional or ablative treatments may be avoided in selected patients who receive appropriate counseling and who are able to comply with more intensive and prolonged follow-up requirements.

A retrospective population based cohort study of access to specialist palliative care in the last year of life: who is still missing out a decade on?

BACKGROUND: Historically, specialist palliative care has been accessed by a greater proportion of people dying with cancer compared to people with other life-limiting conditions. More recently, a variety of measures to improve access to palliative care for people dying from non-cancer conditions have been implemented. There are few rigorous population-based studies that document changes in palliative care service delivery relative to the number of patients who could benefit from such services. METHOD: A retrospective cohort study of the last year of life of persons with an underlying cause of death in 2009-10 from cancer, heart failure, renal failure, liver failure, chronic obstructive pulmonary disease, Alzheimer's disease, motor neurone disease, Parkinson's disease, Huntington's disease and/or HIV/AIDS. The proportion of decedents receiving specialist palliative care was compared to a 2000-02 cohort. Logistic regression models were used identify social and demographic factors associated with accessing specialist palliative care. RESULTS: There were 12,817 deaths included into the cohort; 7166 (56 %) from cancer, 527 (4 %) from both cancer and non-cancer conditions and 5124 (40 %) from non-cancer conditions. Overall, 46.3 % of decedents received community and/or hospital based specialist palliative care; a 3.5 % (95 % CI 2.3-4.7) increase on specialist palliative care access reported ten years earlier. The majority (69 %; n = 4928) of decedents with cancer accessed palliative care during the last year of life. Only 14 % (n = 729) of decedents with non-cancer conditions accessed specialist palliative care, however, this represented a 6.1 % (95 % CI 4.9-7.3) increase on the specialist palliative care access reported for the same decedent group ten years earlier. Compared to decedents with heart failure, increased odds of palliative care access was observed for decedents with cancer (OR 10.5; 95 % CI 9.1-12.2), renal failure (OR 1.5; 95 % CI 1.3-1.9), liver failure (OR 2.3; 95 % CI 1.7-3.3) or motor neurone disease (OR 4.5; 95 % CI 3.1-6.6). Living in major cities, being female, having a partner and living in a private residence was associated with increased odds of access to specialist palliative care. CONCLUSION: There is small but significant increase in access to specialist palliative care services in Western Australia, specifically in patients dying with non-cancer conditions.

Health Service Use and Mortality of the Elderly Blind.

PURPOSE: To determine whether blindness in older people is associated with increased health service use and mortality. DESIGN: Retrospective matched cohort study from July 1, 1999, through June 30, 2010. PARTICIPANTS: A blind cohort 65 years of age and older from a volunteer blind register and a cohort of age- and gender-matched controls selected randomly from the Western Australian electoral roll. METHODS: Person-level linked hospital, emergency department (ED), mental health, and death records for the blind and control cohorts were used. Generalized estimating equations assuming a negative binomial distribution were used to estimate relative rates of hospital admissions, lengths of stay, and mortality after adjusting for sociodemographic variables and comorbidity. Emergency department and mental health service visits also were quantified. MAIN OUTCOME MEASURES: Relative rates of hospital admissions, lengths of stay, and mortality, as well as crude proportions of ED and mental health service visits. RESULTS: The blind cohort comprised 1726 individuals alongside 1726 matched controls; 39% were men, and the mean age was 83 years. Combined, the cohorts accumulated a total of 34 130 hospital admissions amounting to 201 867 bed-days. After adjusting for the principal reason for hospital admission and comorbidity, the blind cohort was admitted to the hospital 11% (95% confidence interval [CI], 6%-17%) more often than the control cohort. The blind cohort also stayed in the hospital longer than the controls, but this effect varied by age. Blind participants 65 to 69 years of age spent 88% more days (95% CI, 27%-178%) in the hospital compared with age-matched controls, whereas there was no difference in length of stay between the cohorts by 80 years of age (rate ratio, 1.10; 95% CI, 0.97-1.25). A larger proportion of the blind cohort visited a hospital ED and accessed mental health services compared with the control cohort. CONCLUSIONS: Health service use is increased for the elderly blind compared with age-matched controls after accounting for comorbidity. The elderly blind have more hospital admissions, ED visits, and mental health-related visits. The younger elderly blind stay longer in hospital. However, there was no evidence of worse mortality outcomes after adjusting for comorbidity.

Cross border hospital use: analysis using data linkage across four Australian states.

OBJECTIVE: To determine the quality and effectiveness of national data linkage capacity by performing a proof-of-concept project investigating cross-border hospital use and hospital-related deaths. DESIGN, PARTICIPANTS AND SETTING: Analysis of person-level linked hospital separation and death registration data of all public and private hospital patients in New South Wales, Queensland and Western Australia and of public hospital patients in South Australia, totalling 7.7 million hospital patients from 1 July 2004 to 30 June 2009. MAIN OUTCOME MEASURES: Counts and proportions of hospital stays and patient movement patterns. RESULTS: 223 262 patients (3.0%) travelled across a state border to attend hospitals, in particular, far northern and western NSW patients travelling to Queensland and SA hospitals, respectively. A further 48 575 patients (0.6%) moved their place of residence interstate between hospital visits, particularly to and from areas associated with major mining and tourism industries. Over 11 000 cross-border hospital transfers were also identified. Of patients who travelled across a state border to hospital, 2800 (1.3%) died in that hospital. An additional 496 deaths recorded in one jurisdiction occurred within 30 days of hospital separation from another jurisdiction. CONCLUSIONS: Access to person-level data linked across jurisdictions identified geographical hot spots of cross-border hospital use and hospital-related deaths in Australia. This has implications for planning of health service delivery and for longitudinal follow-up studies, particularly those involving mobile populations.

Accuracy and completeness of patient pathways--the benefits of national data linkage in Australia.

BACKGROUND: The technical challenges associated with national data linkage, and the extent of cross-border population movements, are explored as part of a pioneering research project. The project involved linking state-based hospital admission records and death registrations across Australia for a national study of hospital related deaths. METHODS: The project linked over 44 million morbidity and mortality records from four Australian states between 1st July 1999 and 31st December 2009 using probabilistic methods. The accuracy of the linkage was measured through a comparison with jurisdictional keys sourced from individual states. The extent of cross-border population movement between these states was also assessed. RESULTS: Data matching identified almost twelve million individuals across the four Australian states. The percentage of individuals from one state with records found in another ranged from 3-5%. Using jurisdictional keys to measure linkage quality, results indicate a high matching efficiency (F measure 97 to 99%), with linkage processing taking only a matter of days. CONCLUSIONS: The results demonstrate the feasibility and accuracy of undertaking cross jurisdictional linkage for national research. The benefits are substantial, particularly in relation to capturing the full complement of records in patient pathways as a result of cross-border population movements. The project identified a sizeable 'mobile' population with hospital records in more than one state. Research studies that focus on a single jurisdiction will under-enumerate the extent of hospital usage by individuals in the population. It is important that researchers understand and are aware of the impact of this missing hospital activity on their studies. The project highlights the need for an efficient and accurate data linkage system to support national research across Australia.

A pragmatic approach to embedding patient blood management in a tertiary hospital.

BACKGROUND: We describe the implementation and impact of a patient blood management program (PBMP) in an Australian teaching hospital. STUDY DESIGN AND METHODS: A PBMP was introduced at a single tertiary care hospital in 2009 as a pilot for the Western Australian Health Department statewide PBMP. The first 3 years of interventions aimed to make effective use of preoperative clinics, manage perioperative anemia, improve perioperative hemostasis, reduce blood sample volumes, and implement restrictive transfusion triggers and a single-unit transfusion policy. RESULTS: Between 2008 and 2011, admissions to Fremantle Hospital and Health Services increased by 22%. Using 2008 as a reference year, the mean number of red blood cell (RBC) units per admission declined 26% by 2011. Use of fresh-frozen plasma and platelets showed 38 and 16% declines, respectively. Cryoprecipitate increased 7% over the 4-year period. For elective admissions between 2008 and 2011, the leading decline in RBC transfusion rate was seen in cardiothoracic surgery (27.5% to 12.8%). The proportion of single RBC unit use increased from 13% to 28% (p < 0.001), and the proportion of double units decreased from 48% to 37% (p < 0.001). CONCLUSION: This is the first tertiary hospital in Australia to establish a multidisciplinary multimodal PBMP. Interventions across disciplines resulted in decreased use of RBC units especially in orthopedic and cardiothoracic surgery. Continuing education and feedback to specialties will maintain the program, improve patient outcomes, and decrease the transfusion rate.

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.

Technical challenges of providing record linkage services for research.

BACKGROUND: Record linkage techniques are widely used to enable health researchers to gain event based longitudinal information for entire populations. The task of record linkage is increasingly being undertaken by specialised linkage units (SLUs). In addition to the complexity of undertaking probabilistic record linkage, these units face additional technical challenges in providing record linkage 'as a service' for research. The extent of this functionality, and approaches to solving these issues, has had little focus in the record linkage literature. Few, if any, of the record linkage packages or systems currently used by SLUs include the full range of functions required. METHODS: This paper identifies and discusses some of the functions that are required or undertaken by SLUs in the provision of record linkage services. These include managing routine, on-going linkage; storing and handling changing data; handling different linkage scenarios; accommodating ever increasing datasets. Automated linkage processes are one way of ensuring consistency of results and scalability of service. RESULTS: Alternative solutions to some of these challenges are presented. By maintaining a full history of links, and storing pairwise information, many of the challenges around handling 'open' records, and providing automated managed extractions are solved. A number of these solutions were implemented as part of the development of the National Linkage System (NLS) by the Centre for Data Linkage (part of the Population Health Research Network) in Australia. CONCLUSIONS: The demand for, and complexity of, linkage services is growing. This presents as a challenge to SLUs as they seek to service the varying needs of dozens of research projects annually. Linkage units need to be both flexible and scalable to meet this demand. It is hoped the solutions presented here can help mitigate these difficulties.

Australian population trends and disparities in cholinesterase inhibitor use, 2003 to 2010.

BACKGROUND: The Australian Pharmaceutical Benefits Scheme (PBS) first subsidized cholinesterase inhibitors (CEIs) for Alzheimer's disease in 2001, introducing a novel therapy for a previously untreatable common condition. This study aims to determine Australian rates of CEI use and to assess equality of access to treatment based on socioeconomic status and geographic remoteness. METHODS: Pharmaceutical claims records were used to identify all Australians prescribed CEIs between January 2003 and December 2010. Age-standardized and sex-adjusted index prescription rates were derived using the total Australian population as the denominator to examine temporal trends and the impacts of socioeconomic and geographic disadvantage on CEI index prescription rates. RESULTS: Index prescription rates peaked in 2004 at 92.5 per 100,000 person-years, declining to between 70.2 and 73.5 for years 2006 to 2010. Rates were highest in the 85- to 89-year age group and 2.6-fold higher in the least socioeconomic disadvantaged population when compared with the most disadvantaged population. In major cities in Australia, index prescription rates were 1.4 to 1.7 times greater compared with remote areas. CONCLUSIONS: Increasing geographic remoteness and socioeconomic disadvantage are associated with lower CEI index prescription rates, indicating inequities in the management of Alzheimer's disease in Australia.

An evaluation framework for comparing geocoding systems.

BACKGROUND: Geocoding, the process of converting textual information describing a location into one or more digital geographic representations, is a routine task performed at large organizations and government agencies across the globe. In a health context, this task is often a fundamental first step performed prior to all operations that take place in a spatially-based health study. As such, the quality of the geocoding system used within these agencies is of paramount concern to the agency (the producer) and researchers or policy-makers who wish to use these data (consumers). However, geocoding systems are continually evolving with new products coming on the market continuously. Agencies must develop and use criteria across a number axes when faced with decisions about building, buying, or maintaining any particular geocoding systems. To date, published criteria have focused on one or more aspects of geocode quality without taking a holistic view of a geocoding system's role within a large organization. The primary purpose of this study is to develop and test an evaluation framework to assist a large organization in determining which geocoding systems will meet its operational needs. METHODS: A geocoding platform evaluation framework is derived through an examination of prior literature on geocoding accuracy. The framework developed extends commonly used geocoding metrics to take into account the specific concerns of large organizations for which geocoding is a fundamental operational capability tightly-knit into its core mission of processing health data records. A case study is performed to evaluate the strengths and weaknesses of five geocoding platforms currently available in the Australian geospatial marketplace. RESULTS: The evaluation framework developed in this research is proven successful in differentiating between key capabilities of geocoding systems that are important in the context of a large organization with significant investments in geocoding resources. Results from the proposed methodology highlight important differences across all axes of geocoding system comparisons including spatial data output accuracy, reference data coverage, system flexibility, the potential for tight integration, and the need for specialized staff and/or development time and funding. Such results can empower decisions-makers within large organizations as they make decisions and investments in geocoding systems.

Hospitalization rates of children who are blind.

BACKGROUND: To evaluate the impact of blindness on hospitalization rates of children. DESIGN: Matched cohort study. PARTICIPANTS: Children confirmed as legally blind (2003-2009), age- and gender-matched to control cohort of normally sighted children from the state register of births. METHODS: The rates and reasons for admission to hospital were compared using hospital morbidity records. The association of blindness with rates of admission and length of stay in hospital, 2003-2010, were estimated using multivariate negative binomial regression models. MAIN OUTCOME MEASURES: Descriptive statistics, incident rate ratios, and predicted means for hospital separations and length of stay. RESULTS: Fifty-nine blind and 59 control children had a combined total of 107 separations accounting for 237 bed days in hospital after the index date of legal blindness. The median age at the index date was 8 years. Over 90% of separations and 92% of bed days were incurred by 22 blind children. Blind children had four (95% confidence interval 1.9-9.3) times more hospital separations and stayed in hospital six (95% confidence interval 1.9-17.5) times longer than the control cohort children. There were more than 40 times as many comorbidities recorded by the blind children (n = 201) compared with the control children (n = 5). A third of the blind children were hospitalized for respiratory conditions. CONCLUSIONS: Children who are born or become blind in childhood have more and longer periods in hospital than sighted children likely because of complex comorbid health problems. There was a disproportionate incidence of comorbid respiratory diseases in the blind children.

The effect of data cleaning on record linkage quality.

BACKGROUND: Within 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. METHODS: A 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. RESULTS: Data 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. CONCLUSIONS: Data cleaning techniques have minimal effect on linkage quality. Care should be taken during the data cleaning process.

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

BACKGROUND: The 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". METHODS: The 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. RESULTS: The 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. CONCLUSIONS: This 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.

Burden of stroke in indigenous Western Australians: a study using data linkage.

BACKGROUND AND PURPOSE: Despite the disproportionate burden of cardiovascular disease among indigenous Australians, information on stroke is sparse. This article documents the incidence and burden of stroke (in disability-adjusted life years) in indigenous and non-indigenous people in Western Australia (1997-2002), a state resident to 15% of indigenous Australians comprising 3.4% of the population of Western Australia. METHODS: Indigenous and non-indigenous stroke incidence and excess mortality rates were estimated from linked hospital and mortality data, with adjustment for nonadmitted events. Nonfatal burden was calculated from nonfatal incidence, duration (modeled from incidence, excess mortality, and remission), and disability weights. Stroke death counts formed the basis of fatal burden. Nonfatal and fatal burden were summed to obtain disability-adjusted life years, by indigenous status. RESULTS: The total burden was 55 099 and 2134 disability-adjusted life years in non-indigenous and indigenous Western Australians, respectively. The indigenous to non-indigenous age-standardized stroke incidence rate ratio (≥15 years) was 2.6 in males (95% CI, 2.3-3.0) and 3.0 (95% CI, 2.6-3.5) in females, with similar rate ratios of disability-adjusted life years. The burden profile differed substantially between populations, with rate ratios being highest at younger ages. CONCLUSIONS: The differential between indigenous and non-indigenous stroke burden is considerable, highlighting the need for comprehensive intersectoral interventions to reduce indigenous stroke incidence and improve outcomes. Programs to reduce risk factors and increase access to culturally appropriate stroke services are required. The results here provide the quantitative basis for policy development and monitoring of stroke outcomes.

Whole population trends in complications of cataract surgery over 22 years in Western Australia.

OBJECTIVE: To examine the trends in major complications of cataract surgery in the Western Australian population over 22 years. DESIGN: Population-based study. PARTICIPANTS: We included 129 982 cataract/lens surgery patients across 46 health facilities. METHODS: Using the Western Australian Data Linkage System, we identified all patients who underwent cataract/lens surgery in Western Australia between 1980 and 2001. Complications of interest were identified from those patients admitted to hospital or who underwent unplanned surgery after cataract surgery and were validated by medical record review. MAIN OUTCOME MEASURES: Admission for retinal detachment, dropped nucleus, wound dehiscence, pseudophakic corneal edema, intraocular lens (IOL) dislocation, and postoperative endophthalmitis requiring surgery. RESULTS: There were 129 982 cataract/lens procedures and 2087 (1.6%) complications. Complications fell almost 70% over the study period. Retinal detachment (n = 905; 0.70%) was most common, followed by IOL dislocation (n = 361; 0.28%), endophthalmitis (n = 228; 0.18%), wound dehiscence (n = 227; 0.17%), pseudophakic corneal edema (n = 207; 0.16%), and dropped nucleus (n = 159; 0.12%). The incidence of complications lessened over time, except for IOL dislocations, which has increased since 1995. Overall, the risk of complications after phacoemulsification halved since it was introduced in the late 1990s (incidence rate ratio, 0.52; 95% confidence interval, 0.37-0.74), whereas complications after extracapsular extraction (ECCE) have increased over recent years. CONCLUSIONS: Cataract surgery remains an extremely safe procedure with comparatively few major complications. Changes in operative techniques have been accompanied by a significant decrease in complication rates over time, although the increase in IOL dislocations and complications after ECCE warrants further study. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.