The importance of including aliases in data linkage with vulnerable populations.

BACKGROUND: Records pertaining to individuals whose identity cannot be verified with legal documentation may contain errors, or be incorrect by intention of the individual. Probabilistic data linkage, especially in vulnerable populations where the incidence of such records may be higher, must be considerate of the usage of these records. METHODS: A data linkage was conducted between Queensland Youth Justice records and the Australian National Death Index. Links were assessed to determine how often they were made using the unverified (alias) records that would not have been made in their absence (i.e. links that were not also made using solely verified records). Anomalies in the linked records were investigated in order to make evaluations of the sensitivity and specificity of the linkage, compared to the links made using only verified records. RESULTS: From links made using verified records only, 1309 deaths were identified (2.6% of individuals). Using alias records in addition, the number of links increased by 16%. Links made using alias records only were more common in females, and those born after 1985. Different records belonging to the same individual in the justice dataset did not link to different death records, however there were instances of the same death record linking to multiple cohort individuals. CONCLUSIONS: The inclusion of aliases in data linkage in youths involved in the justice system increased mortality ascertainment without any discernible increase in false positive matches. We therefore conclude that alias records should be included in data linkage procedures in order to avoid biased attenuation of ascertainment in vulnerable populations, leading to the concealment of health inequality.

The cost of hospital-acquired complications for older people with and without dementia; a retrospective cohort study.

BACKGROUND: Increased length of stay and high rates of adverse clinical events in hospitalised patients with dementia is stimulating interest and debate about which costs may be associated and potentially avoided within this population. METHODS: A retrospective cohort study was designed to identify and compare estimated costs for older people in relation to hospital-acquired complications and dementia. Australia's most populous state provided a census sample of 426,276 discharged overnight public hospital episodes for patients aged 50+ in the 2006-07 financial year. Four common hospital-acquired complications (urinary tract infections, pressure areas, pneumonia, and delirium) were risk-adjusted at the episode level. Extra costs were attributed to patient length of stay above the average for each patient's Diagnosis Related Group, with separate identification of fixed and variable costs (all in Australian dollars). RESULTS: These four complications were found to be associated with 6.4% of the total estimated cost of hospital episodes for people over 50 (A$226million/A$3.5billion), and 24.7% of the estimated extra cost of above-average length of stay spent in hospital for older patients (A$226million/A$914million). Dementia patients were more likely than non-dementia patients to have complications (RR 2.5, p <0.001) and these complications comprised 22.0% of the extra costs (A$49million/A$226million), despite only accounting for 10.4% of the hospital episodes (44,488/426,276). For both dementia and non-dementia patients, the complications were associated with an eightfold increase in length of stay (813%, or 3.6 days/0.4 days) and doubled the increased estimated mean episode cost (199%, or A$16,403/A$8,240). CONCLUSION: Urinary tract infections, pressure areas, pneumonia and delirium are potentially preventable hospital-acquired complications. This study shows that they produce a burdensome financial cost and reveals that they are very important in understanding length of stay and costs in older and complex patients. Once a complication occurs, the cost is similar for people with and without dementia. However, they occur more often among dementia patients. Advances in models of care, nurse skill-mix and healthy work environments show promise in prevention of these complications for dementia and non-dementia patients.

Characteristics of rural hospital services for people with dementia: findings from the Hospital Dementia Services Project.

OBJECTIVE: To obtain information about aged care services in rural New South Wales public hospitals, and to describe key operational aspects of their service delivery models. DESIGN: A mixed methods design was used to combine data collected from: (i) a survey of public hospitals and (ii) qualitative site visits in a sample of eleven rural sites. SETTING: Rural public hospitals in NSW, Australia. PARTICIPANTS: Qualitative data were collected from multidisciplinary clinicians, managers and community service providers who participated in site visits in 2010 and from surveys of NSW public hospitals in 2009/10 about aged care and dementia services. RESULTS: Survey and site visit findings demonstrated that rural hospitals have fewer secure beds for managing patients with disturbed behaviour due to dementia and delirium and fewer speciality aged care staff than metropolitan hospitals. Site visit participants also described how secure environments can aid care for people with dementia even in the absence of clinical specialists. CONCLUSION: The care of people with dementia in rural hospitals is constrained by access to specialist aged care staff and the physical environment of the hospital. Clinicians are adept at maximising resources to manage diagnosis and transitions for people with dementia. Further understanding of how key operational aspects of clinical leadership and environmental modifications impact on a range of patient outcomes would be valuable.

The Hospital Dementia Services Project: age differences in hospital stays for older people with and without dementia.

BACKGROUND: People with dementia may have adverse outcomes following periods of acute hospitalization. This study aimed to explore the effects of age upon hospitalization outcomes for patients with dementia in comparison to patients without dementia. METHODS: Data extracted from the New South Wales Admitted Patient Care Database for people aged 50 years and over for the period July 2006 to June 2007 were linked to create person-based records relating to both single and multiple periods of hospitalization. This yielded nearly 409,000 multi-day periods of hospitalization relating to almost 253,000 persons. Using ICD-10-AM codes for dementia and other principal diagnoses, the relationship between age and hospitalization characteristics were examined for people with and without dementia. RESULTS: Dementia was age-related, with 25% of patients aged 85 years and over having dementia compared with 0.9% of patients aged 50-54 years. People with dementia were more likely to be admitted for fractured femurs, lower respiratory tract infections, urinary tract infections and head injuries than people without dementia. Mean length of stay for admissions for people with dementia was 16.4 days and 8.9 days for those without dementia. People with dementia were more likely than those without to be re-admitted within three months for another multi-day stay. Mortality rates and transfers to nursing home care were higher for people with dementia than for people without dementia. These outcomes were more pronounced in younger people with dementia. CONCLUSION: Outcomes of hospitalization vary substantially for patients with dementia compared with patients without dementia and these differences are frequently most marked among patients aged under 65 years.

Alcohol-related cognitive impairment in New South Wales hospital patients aged 50 years and over.

OBJECTIVES: The aim of this study was to describe the principal reasons for admission, medical comorbidities, interventions and outcomes of patients admitted to New South Wales hospitals with alcohol-related cognitive impairment. METHODS: We extracted data from the NSW Admitted Patient Care Database for nearly 410 000 multi-day hospital admissions from 222 public hospitals ending between July 2006 and June 2007 for people aged 50 and over. Data linkage using a unique patient identifier, derived by the Centre for Health Record Linkage identified hospital transfers and readmissions for individual patients. Using ICD10-AM codes, we identified patients with alcohol-related dementia, amnesic syndrome due to alcohol, and Wernicke's encephalopathy, their principal reasons for admission and medical comorbidities, and procedures undertaken. Outcomes were length of stay, mortality, discharge destination, and readmission. RESULTS: A total of 462 patients diagnosed with alcohol-related dementia (n = 300; 82% male, mean age 63.9 years), Wernicke's encephalopathy (n = 77) or amnesic syndrome due to alcohol (n = 126) were identified with overlap between diagnoses. Alcohol-related dementia occurred in 1.4% of dementia patients, and was more likely to occur in younger age groups and men than other types of dementia. Alcohol-related mental disorder was recorded in 70% of alcohol-related dementia multi-day admissions: dependence (52%), 'harmful use' (11%) and withdrawal (12%). Principal reasons for admission for multi-day stays included alcohol-related mental disorder (18%), liver disease (11%) and injuries/poisonings (10%). Medical comorbidity was common. Like other dementia patients, alcohol-related dementia patients had longer length of stay (mean of 15 days) than non-dementia patients and more transfers to residential care (7%). However, mortality was similar to non-dementia patients (5%). Discharge at own risk was high (3.7%). CONCLUSIONS: Alcohol-related dementia is a preventable and potentially reversible condition. Investigation of intervention strategies initiated during hospitalization are warranted.

Empirical aspects of record linkage across multiple data sets using statistical linkage keys: the experience of the PIAC cohort study.

BACKGROUND: In Australia, many community service program data collections developed over the last decade, including several for aged care programs, contain a statistical linkage key (SLK) to enable derivation of client-level data. In addition, a common SLK is now used in many collections to facilitate the statistical examination of cross-program use. In 2005, the Pathways in Aged Care (PIAC) cohort study was funded to create a linked aged care database using the common SLK to enable analysis of pathways through aged care services. Linkage using an SLK is commonly deterministic. The purpose of this paper is to describe an extended deterministic record linkage strategy for situations where there is a general person identifier (e.g. an SLK) and several additional variables suitable for data linkage. This approach can allow for variation in client information recorded on different databases. METHODS: A stepwise deterministic record linkage algorithm was developed to link datasets using an SLK and several other variables. Three measures of likely match accuracy were used: the discriminating power of match key values, an estimated false match rate, and an estimated step-specific trade-off between true and false matches. The method was validated through examining link properties and clerical review of three samples of links. RESULTS: The deterministic algorithm resulted in up to an 11% increase in links compared with simple deterministic matching using an SLK. The links identified are of high quality: validation samples showed that less than 0.5% of links were false positives, and very few matches were made using non-unique match information (0.01%). There was a high degree of consistency in the characteristics of linked events. CONCLUSIONS: The linkage strategy described in this paper has allowed the linking of multiple large aged care service datasets using a statistical linkage key while allowing for variation in its reporting. More widely, our deterministic algorithm, based on statistical properties of match keys, is a useful addition to the linker's toolkit. In particular, it may prove attractive when insufficient data are available for clerical review or follow-up, and the researcher has fewer options in relation to probabilistic linkage.

Linkage of health and aged care service events: comparing linkage and event selection methods.

BACKGROUND: Data linkage is a technique that has long been used to connect information across several disparate data sources--most commonly for medical and population health research. Often the purpose is to connect data for individuals over extended time periods or across different service settings, and so person-based linkage using detailed personal information is preferred. Linkage which aims to link connected events, on the other hand, requires information about the time and place of the event as well as the person or persons involved in that event in order to make high quality linkages. This paper describes the detailed process of event linkage and compares directly an event-based linkage method for identifying transition events between two care sectors in Australia with a well-established high quality longitudinal person-based linkage which facilitates identification of event data for individuals. METHODS: Direct comparisons are made between transition events identified using an event-based linkage and an existing person-based linkage for people moving from hospital into aged care in Western Australia. Several aspects of event-based linkage are examined: refinement of the strategy to reduce false positives, causes of false positives and false negatives, quality of the linked event dataset, and utility of the linked event dataset for transition analysis. RESULTS: Over 97% of the event-based links were among those selected using the person-based linkage and over 90% of the latter were identified by the event-based method, with the remainder missed mostly due to differences in reported event date or residential region. Consequently the two linked datasets were sufficiently similar to give very similar results for analyses, but the actual volume of movement from hospital to RAC was underestimated by about 10% by the event-based method. CONCLUSION: This project has allowed a 'preferred event' event-based linkage strategy to be selected and deployed across Australia to study movements from hospital to residential aged care facilities using databases in which only limited personal information is available, but event dates and details can be readily accessed. The utility of this approach in other transition situations depends on the volume of movement and the accuracy of recording information in each setting.

Predicting excess cost for older inpatients with clinical complexity: A retrospective cohort study examining cognition, comorbidities and complications.

BACKGROUND: Hospital-acquired complications increase length of stay and contribute to poorer patient outcomes. Older adults are known to be at risk for four key hospital-acquired complications (pressure injuries, pneumonia, urinary tract infections and delirium). These complications have been identified as sensitive to nursing characteristics such as staffing levels and level of education. The cost of these complications compared to the cost of admission severity, dementia, other comorbidities or age has not been established. METHOD: To investigate costs associated with nurse-sensitive hospital-acquired complications in an older patient population 157,178 overnight public hospital episodes for all patients over age 50 from one Australian state, 2006/07 were examined. A retrospective cohort study design with linear regression analysis provided modelling of length-of-stay costs. Explanatory variables included patient age, sex, comorbidities, admission severity, dementia status, surgical status and four complications. Extra costs were based on above-average length-of-stay for each patient's Diagnosis Related Group from hospital discharge data. RESULTS: For adults over 50 who have length of stay longer than average for their diagnostic condition, comorbid dementia predicts an extra cost of A$874, (US$1,247); any one of four key complications predicts A$812 (US$1,159); each increase in admission severity score predicts A$295 ($US421); each additional comorbidity predicts A$259 (US$370), and for each year of age above 50 predicts A$20 (US$29) (all estimates significant at p<0.0001). DISCUSSION: Hospital-acquired complications and dementia cost more than other kinds of inpatient complexity, but admission severity is a better predictor of excess cost. Because complications are potentially preventable and dementia care in hospitals can be improved, risk-reduction strategies for common complications, particularly for patients with dementia could be cost effective. CONCLUSIONS: Complications and dementia were found to cost more than other kinds of inpatient complexity.

Event-based record linkage in health and aged care services data: a methodological innovation.

BACKGROUND: The interface between acute hospital care and residential aged care has long been recognised as an important issue in aged care services research in Australia. However, existing national data provide very poor information on the movements of clients between the two sectors. Nevertheless, there are national data sets which separately contain data on individuals' hospital episodes and stays in residential aged care, so that linking the two data sets-if feasible-would provide a valuable resource for examining relationships between the two sectors. As neither name nor common person identifiers are available on the data sets, other information needs to be used to link events relating to inter-sector movement. METHODS: Event-based matching using limited demographic data in conjunction with event dates to match events in two data sets provides a possible method for linking related events. The authors develop a statistical model for examining the likely prevalence of false matches, and consequently the number of true matches, among achieved matches when using anonymous event-based record linkage to identify transition events. RESULTS: Theoretical analysis shows that for event-based matching the prevalence of false matches among achieved matches (a) declines as the events of interest become rarer, (b) declines as the number of matches increases, and (c) increases with the size of the population within which matching is taking place. The method also facilitates the examination of the trade-off between false matches and missed matches when relaxing or tightening linkage criteria. CONCLUSION: Event-based record linkage is a method for linking related transition events using event dates and basic demographic variables (other than name or person identifier). The likely extent of false links among achieved links depends on the two event rates, the match rate and population size. Knowing these, it is possible to gauge whether, for a particular study, event-based linkage could provide a useful tool for examining movements. Analysis shows that there is a range of circumstances in which event-based record linkage could be applied to two event-level databases to generate a linked database useful for transition analysis.

Hospital Dementia Services Project: aged care and dementia services in New South Wales hospitals.

AIMS: To describe the availability of aged care and dementia services in public hospitals in New South Wales (NSW), Australia in 2006/2007. METHOD: Hospitals were surveyed about issues relevant to dementia in acute care including the types of aged care wards and staff, policies, practices, clinics, community services and resources for dementia care. RESULTS: Responses were obtained from 163 hospitals (82%); responding hospitals represented 93.4% of NSW hospital beds, 96.7% of multiday episodes of care. Hospitals that had a Specialist Mental Health Service for Older People (SMHSOP) and an Aged Care Service (ACS) had the highest levels of dementia-related services and policies. Few hospitals without ACS or SMHSOP had clinics for dementia assessment, secure beds for disturbed behaviour, or services to manage patients with dementia and medical or behavioural comorbidity in the community. CONCLUSION: Dementia services in NSW hospitals are closely aligned with ACS and SMHSOP, with limited dementia services in hospitals without ACS or SMHSOP.

Potentially preventable complications of urinary tract infections, pressure areas, pneumonia, and delirium in hospitalised dementia patients: retrospective cohort study.

OBJECTIVES: To identify rates of potentially preventable complications for dementia patients compared with non-dementia patients. DESIGN: Retrospective cohort design using hospital discharge data for dementia patients, case matched on sex, age, comorbidity and surgical status on a 1 : 4 ratio to non-dementia patients. SETTING: Public hospital discharge data from the state of New South Wales, Australia for 2006/2007. PARTICIPANTS: 426 276 overnight hospital episodes for patients aged 50 and above (census sample). MAIN OUTCOME MEASURES: Rates of preventable complications, with episode-level risk adjustment for 12 complications that are known to be sensitive to nursing care. RESULTS: Controlling for age and comorbidities, surgical dementia patients had higher rates than non-dementia patients in seven of the 12 complications: urinary tract infections, pressure ulcers, delirium, pneumonia, physiological and metabolic derangement (all at p<0.0001), sepsis and failure to rescue (at p<0.05). Medical dementia patients also had higher rates of these complications than did non-dementia patients. The highest rates and highest relative risk for dementia patients compared with non-dementia patients, in both medical and surgical populations, were found in four common complications: urinary tract infections, pressure areas, pneumonia and delirium. CONCLUSIONS: Compared with non-dementia patients, hospitalised dementia patients have higher rates of potentially preventable complications that might be responsive to nursing interventions.

Transitions from hospital to residential aged care in Australia.

AIM: To investigate movement of people from hospital into residential aged care. METHODS: An innovative record linkage method was implemented to create a national database to investigate transitions from hospital into aged care. RESULTS: In 2001-2002, 3.2% of hospitalisations for people aged 65+ ended with admission into residential aged care. A further 5.5% were for people already living permanently in care. Nationally, more people were admitted into permanent care from hospital than from the community. Factors important in predicting admission to aged care from hospital included length of hospital stay, diagnoses, region of usual residence and hospital jurisdiction. CONCLUSION: Individually, national hospital and aged care datasets do not provide adequate information on movement between the sectors. Linking the data allowed the first national investigation into movement from hospital into aged care. Results indicate the importance of investigating interactions of service provision (both supply and demand driven) at the local level.

The acute-aged care interface: exploring the dynamics of 'bed blocking'.

OBJECTIVE: To understand the dynamics underlying 'bed-blocking' in Australian public hospitals that is frequently blamed on older patients. METHODS: Analysis of primary and secondary data of utilisation patterns of hospital and aged care services by older Australians. RESULTS: A model of the dynamics at the acute-aged care interface was developed, in which the pathway into permanent high-care Residential Aged Care (RAC) is conceptualised as competing queues for available places by applicants from the hospital, the community and from within RAC facilities. The hospital effectively becomes a safety net to accommodate people with high-care needs who cannot be admitted into RAC in a timely manner. CONCLUSION: The model provides a useful tool to explore some of the issues that give rise to access-block within the public hospital system. Access-block cannot be understood by viewing the hospital system in isolation from other sectors that support the health and well-being of older Australians.