The impact of first and second eye cataract surgeries on falls: a prospective cohort study.

PURPOSE: The purpose of this study was to investigate the impact of the first and second eye cataract surgeries on the risk of falls in participants with bilateral cataract and to determine which changes in visual measures are associated with changes in the number of falls throughout the cataract surgery process. PATIENTS AND METHODS: Fifty-five older adults with bilateral cataract aged 55+ years were assessed at three time points during the cataract surgery process, and they completed a falls diary. Two separate generalized estimating equation-negative binomial models were undertaken to assess changes in the number of falls before first eye cataract surgery, between first and second eye surgeries, and after second eye cataract surgery and which changes in visual measures were associated with changes in the number of falls. RESULTS: After adjusting for potential confounding factors, the risk of falls decreased by 54% (incidence rate ratio (IRR) =0.458, 95% CI=0.215-0.974, p=0.04) after first eye cataract surgery only, compared with the period before first eye surgery. The risk of falls decreased by 73% (IRR =0.268, 95% CI =0.114-0.628, p=0.002) after second eye cataract surgery, compared with the period before first eye surgery. Improved binocular visual acuity (IRR =5.488, 95% CI =1.191-25.282, p=0.029) and contrast sensitivity (IRR =0.257, 95% CI =0.070-0.939, p=0.040) were associated with a decrease in the number of falls. CONCLUSION: The study found that first and second eye cataract surgeries reduced the risk of falls among a cohort of bilateral cataract patients with relatively good baseline vision. This suggests that timely first and second eye cataract surgeries could play an important role in reducing the burden due to falls among older adults with cataract.

Psychotropic Medication and Substance Use during Pregnancy by Women with Severe Mental Illness.

BACKGROUND: Sociodemographic factors, alcohol and drug intake, and maternal health are known to be associated with adverse outcomes in pregnancy for women with severe mental illness in addition to their use of psychotropic medication. In this study, we describe the demographic characteristics of women hospitalized for severe mental illness along with their use of medication and other drugs during the pregnancy period. METHODS: A clinical case note review of women with psychosis who were hospitalized at the State Psychiatric Hospital in Western Australia during 1966-1996, gave birth between 1980 and 1992, and received psychiatric treatment during the pregnancy period. The mother's clinical information was available from the case notes and the midwives record. The demographic characteristics of the mothers were described together with their hospitalization pattern and their medication and substance use during the pregnancy period. RESULTS: A total of 428 mothers with a history of severe mental illness were identified who gave birth during 1980-1992. Of these, 164 mothers received psychiatric care during the pregnancy period. One hundred thirty-two had taken psychotropic medication during this period. Mothers who were married, of aboriginal status or living in regional and remote areas appeared less likely to be hospitalized during the pregnancy period, while older mothers and those with a diagnosis of schizophrenia were more likely to be hospitalized. The number of mothers taking psychotropic medication in the first trimester of pregnancy was reduced compared to the previous 6 months. The decline in the number taking substances over the same period was not significant. In all, 16% of the women attempted suicide during the pregnancy period and 10% non-suicidal self-injury. CONCLUSION: The women demonstrate a pattern of decreased use of psychotropic medication use from the period before pregnancy to the first trimester of pregnancy. Our data highlight the importance of women with severe mental illness receiving regular ongoing monitoring and support from their psychiatrist during pregnancy regarding the level of medication required as well as counseling with regard to substance use, non-suicidal self-injury, and attempted suicide.

The Western Australian family connections genealogical project: detection of familial occurrences of single gene and chromosomal disorders.

AIM: To investigate using a Western Australian (WA) genealogical database for the identification of single gene and chromosome disorders among families. METHOD: Hospital admissions for single gene and chromosome disorders recorded during 2000-2006 were identified from the WA Hospital Morbidity Data System. The proportion of these conditions occurring in family groups was then identified using genealogical links created through the WA Family Connections Genealogical Project. RESULTS: There were 216 family clusters among 11,303 people who were recorded as having a genetic or chromosomal disorder on their hospital admission record. The most common single gene conditions found to occur in multiple family members included blood clotting disorders such as Factor VIII deficiency and Von Willebrand's disease, followed by cystic fibrosis, myotonic dystrophies, neurofibromatosis, tuberous sclerosis, and osteogenesis imperfecta. DISCUSSION: Single gene disorders most commonly occurring in multiple family members have been identified using the WA Family Connections Genealogical Project. These disorders reflect the most common single gene disorders requiring hospital admission, but which are not fatal before reproductive age and do not result in a loss of fertility. They are also restricted to disorders with earlier onset, as the WA Family Connections Genealogical Project currently covers 2-3 of the most recent generations. This study demonstrates the utility of record linkage genealogies to identify kindred with genetic disorders, offering a rich resource of information for focused genetic epidemiological research.

Baseline investigations of folate status in Aboriginal and non-Aboriginal West Australians prior to the introduction of mandatory fortification.

OBJECTIVE: In September 2009, Australia implemented mandatory folic acid fortification of wheat flour for bread-making to reduce the incidence of neural tube defects. Our study aimed to establish baseline folate status data in Aboriginal and non-Aboriginal Western Australians. METHODS: Patients who presented at a health service or collection centre for blood tests were invited to participate. One hundred and ninety-one Aboriginals and 159 non-Aboriginals were recruited between April 2008 and September 2009. Participants completed a five-minute questionnaire and had blood taken for red blood cell (RBC) folate and serum vitamin B12. Data were analysed using SPSS (version 17.0.2, SPSS Inc., Chicago, IL, USA). RESULTS: Ten per cent (95% confidence intervals (CI): 5, 19) of the Aboriginal women participants and 26% (95% CI: 16, 40) of men had RBC folate concentrations below 250 ng/mL, the cut-off associated with folate deficiency. None of the non-Aboriginal women (95% CI: 0, 4) and 4% of the non-Aboriginal men (95% CI: 2, 12) had RBC folate concentrations below 250 ng/mL. All participants were vitamin B12 replete. None of the 96 Aboriginal and 8% of non-Aboriginal women aged 16-44 reported consumption of supplements with a daily intake of >400 µg folic acid during the previous week. CONCLUSIONS AND IMPLICATIONS: This study established a baseline of RBC folate, folate consumption and supplement use in Aboriginal and non-Aboriginal groups. We identified 10% of Aboriginal women and none of non-Aboriginal women participants with low folate concentrations. The higher prevalence of folate deficiency in Aboriginal participants suggests they are more likely to benefit from a universal program of folate fortification.

The impact of single gene and chromosomal disorders on hospital admissions in an adult population.

Although the role of single gene and chromosomal disorders in pediatric illness has been recognized since the 1970s, there are few data describing the impact of these often severe disorders on the health of the adult population. In this study, we present population data describing the impact of single gene and chromosomal disorders on hospital admissions of patients aged 20 years and over in Western Australia between 2000 and 2006. The number, length, and cost of admissions were investigated and compared between disease categories and age groups and to hospital admissions for any reason. In total, 73,211 admissions and 8,032 patients were included in the study. The most costly disorders were cystic kidney disease, α-1 anti-trypsin deficiency, hemochromatosis, von Willebrand disease, and cystic fibrosis. Overall, patients with single gene and chromosomal disorders represented 0.5% of the patient population and were responsible for 1.9% of admissions and 1.5% of hospital costs. These data will enable informed provision of health care services for adults with single gene and chromosomal disorders in Australia.

First trimester predictors of adverse pregnancy outcomes.

AIM: To identify first trimester indicators of adverse pregnancy outcomes. METHOD: Data were obtained from the statewide evaluation of first trimester screening for Down syndrome in Western Australia which included 22,695 pregnancies screened between August 2001 and October 2003. Screening data were linked with pregnancy outcome information from the Hospital Morbidity Database and the Birth Defects Registry. The odds ratios (OR) of adverse outcomes were analysed for combined risk incorporating maternal age, nuchal translucency (NT) and biochemical parameters and then separately for each parameter (pregnancy-associated plasma protein-A (PAPP-A), free beta human chorionic gonadotropin (beta-hCG) and NT). RESULTS: Risk assessments for first trimester combined screening are derived from maternal age, ultrasound measurement of fetal NT, maternal serum free beta-hCG and PAPP-A. Increased combined risk for Down syndrome was significantly (P < 0.01) associated with spontaneous loss at or before 24 weeks gestation (OR 13.51), birth defects (OR 6.58) and preterm birth at or before 32 weeks gestation (OR 3.2). Maternal serum PAPP-A below the 5th centile was associated with Down syndrome (OR 8.43), spontaneous loss before 24 weeks (OR 5.04) and later than 24 weeks (OR 4.50), preterm delivery before 32 weeks (OR 3.11) and before 37 weeks (OR 2.24). NT above the 95th centile was associated with Down syndrome (OR 43.91), birth defects (OR 4.02) and spontaneous loss before 24 weeks (OR 6.24). Low levels of free beta-hCG and increased NT were less consistently associated with adverse outcomes and high levels of free beta-hCG showed limited use as an indicator. The detection rates for all outcomes other than Down syndrome were less than 40%. CONCLUSION: Biochemical indicators and NT that are measured during first trimester screening for Down syndrome show a number of associations with adverse outcomes, but do not show appropriate performance characteristics for screening tests. These data are consistent with the view that the individual components, specifically low PAPP-A levels alone, do not provide an effective screening tool for adverse pregnancy outcomes.

Length of comorbidity lookback period affected regression model performance of administrative health data.

BACKGROUND AND OBJECTIVE: The impact of different comorbidity ascertainment lookback periods on modeling posthospitalization mortality and readmission was examined. METHODS: Index cases comprised medical (n = 326,456) and procedural (n = 349,686) patients with a hospital admission from 1990-1996. Administrative hospital data were extracted for 102 comorbidities, ascertained at index admission and for 1-, 2-, 3-, and 5-year lookback periods. Deaths and readmissions were identified within 12 months and 30 days of separation, respectively. Hierarchically nested and nonnested Cox regressions as well as Receiver Operator Characteristic Area Under the Curve (ROC-AUC) were used to determine model-fit and predictive ability of lookback period models. RESULTS: The 1-year lookback period provided the best model-fit for both patient groups when modeling mortality. A similar model-fit was seen at index admission for procedural but not medical patients. The superior readmission model employed 5 years of lookback for both patient groups. With one exception, all lookback period models were superior to those abstracting comorbidity from index admission only. Similar results were evident from ROC-AUC, although greater predictive ability was seen with modeling of mortality (0.847-0.923) compared with readmission (0.593-0.681). CONCLUSION: The explanatory power of regression models, when adjusting for comorbidity, is influenced by length of lookback, outcome investigated and clinical subgroup. Shorter periods (approximately 1 year) appear appropriate for modeling posthospitalization mortality, whereas longer lookback periods are superior for readmission outcomes.

High-cost users of hospital beds in Western Australia: a population-based record linkage study.

OBJECTIVE: To describe how high-cost users of inpatient care in Western Australia differ from other users in age, health problems and resource use. DESIGN AND DATA SOURCES: Secondary analysis of hospital data and linked mortality data from the WA Data Linkage System for 2002, with cost data from the National Hospital Cost Data Collection (2001-02 financial year). OUTCOME MEASURES: Comparison of high-cost users and other users of inpatient care in terms of age, health profile (major diagnostic category) and resource use (annualised costs, separations and bed days). RESULTS: Older high-cost users (> or = 65 years) were not more expensive to treat than younger high-cost users (at the patient level), but were costlier as a group overall because of their disproportionate representation (n = 8466; 55.9%). Chronic stable and unstable conditions were a key feature of high-cost users, and included end stage renal disease, angina, depression and secondary malignant neoplasms. High-cost users accounted for 38% of both inpatient costs and inpatient days, and 26% of inpatient separations. CONCLUSION: Ageing of the population is associated with an increase in the proportion of high-cost users of inpatient care. High costs appear to be needs-driven. Constraining high-cost inpatient use requires more focus on preventing the onset and progression of chronic disease, and reducing surgical complications and injuries in vulnerable groups.

Health care financing and public responses: use of private insurance in Western Australia during 1980-2001.

OBJECTIVES: The aim was to identify and explain trends and cut points in payment classification (privately insured or otherwise) for episodes of hospitalisation in Western Australia. METHODS: Hospital morbidity data from 1980 to 2001 were used to produce trend lines of the proportion of hospital separations in each payment category in each year in age and clinical subgroups. RESULTS: The most significant changes in payment classification over time were found in all groups between 1980 and 1984, corresponding to a period when free public hospital care in Australia was abolished (Sep 1981 to Feb 1984). The trend associated with this policy change rebounded significantly just before the introduction of Medicare in 1984. These observations were consistent over all age groups except in the oldest group (70+ years). This trend was more pronounced for the surgical subgroup compared with other broad clinical categories. More recently, a trend towards increasing public episodes was reversed from 2000 following introduction of incentives for private health cover and sanctions against deferred uptake in younger people. CONCLUSION: The public appeared to adopt a short-term crisis reaction to major policy change but then reversed towards past patterns of behaviour. The implications for policy makers include the need to understand the underlying culture of the population; to realise that attitudes become fixed as people age; and to recognise the difference in the effectiveness of incentive- and deterrent-based policies.

The effect of locational disadvantage on hospital utilisation and outcomes in Western Australia.

This study analyses the effect of location of residence on hospital utilisation and outcomes using geocoded hospital morbidity and mortality data for the Western Australian population from 1994 to 1999. Compared to highly accessible areas, the overall hospital admission rate ratio was 2.27 (95% CI 2.19-2.36) for those in moderately accessible areas and 2.35 (95% CI 2.23-2.47) for those in remote areas. The corresponding ratios for total length of stay were 1.19 (95% CI 1.17-1.20) and 1.25 (95% CI 1.23-1.27) and the hazard ratios for risk of readmission at 30 days were 1.06 (95% CI 1.04-1.07) and 1.17 (95% CI 1.15-1.19). This study represents an important advance in describing the effects of remoteness on health service utilisation and outcomes.

Demographic factors as predictors for hospital admission in patients with chronic disease.

OBJECTIVE: To identify demographic predictors of hospital admission for chronic disease. METHODS: Hospital morbidity records were extracted from the WA Data Linkage System for the period 1994-99 for specific chronic diseases based on national priorities. Poisson regression was used to estimate the effects of Aboriginal and Torres Strait Islander (ATSI) descent, co-morbidity, geography, socio-economic status and possession of health insurance on hospital admission rates. RESULTS: This study has identified some of the main demographic risk factors for hospitalisation in patients with chronic disease as the following: being male, of ATSI descent, living in a relatively disadvantaged Census Collection District and having multiple co-morbidities. Depending on the disease, locational disadvantage and possession of private health insurance were also risk factors. CONCLUSIONS: The study indicates that a crucial component in keeping patients with chronic disease out of hospital is ensuring quality primary care for all members of the community, equipping patients with the necessary skills to self-manage their chronic condition. Particular attention must be given to developing programs that are accessible to the more disadvantaged members of the community. IMPLICATIONS: Programs aimed at keeping patients with chronic disease out of hospital must be targeted at the most vulnerable groups of the population if they are to be effective.

The use of end-quintile comparisons to identify under-servicing of the poor and over-servicing of the rich: a longitudinal study describing the effect of socioeconomic status on healthcare.

BACKGROUND: To demonstrate the use of end-quintile comparisons in assessing the effect of socio-economic status on hospital utilisation and outcomes in Western Australia. METHODS: Hospital morbidity records were extracted from the WA Data Linkage System for the period 1994-99, with follow-up to the end of 2000. Multivariate modelling was used to estimate the effect of socio-economic status on hospital admission rates, average and total length of stay (LOS), cumulative incidence of readmission at 30 days and one year, and case fatality at one year. RESULTS: The study demonstrated higher rate ratios of hospital admission in the more disadvantaged quintiles: rate ratios were 1.31 (95% CI 1.25-1.37) and 1.32 (1.26-1.38) in the first quintile (most disadvantaged) and the second quintile respectively, compared with the fifth quintile (most advantaged). There was a longer total LOS in the most disadvantaged quintile compared with quintile 5 (LOS ratio 1.24; 1.23-1.26). The risk of readmission at 30 days and one year and the risk of death at one year were also greater in those with greater disadvantage: the hazard ratios for quintiles 1:quintile 5 were 1.07 (1.05-1.09), 1.17 (1.16-1.18) and 1.10 (1.07-1.13) respectively. In contradiction to the trends towards higher hospital utilisation and poorer outcomes with increasing social disadvantage, in some MDC's the rate ratio of quintile 1:quintile 2 was less than 1, and quintile 4:quintile 5 was greater than 1. For all surgical admissions the most disadvantaged had a significantly lower admission rate than the second quintile. CONCLUSION: This study has shown that the disadvantaged within Western Australia are more intensive users of hospital services but their outcomes following hospitalisation are worse, consistent with their health status. Instances of overuse in the least disadvantaged and under use in the most disadvantaged have also been identified.

Improved methods for estimating incidence from linked hospital morbidity data.

BACKGROUND: Linked hospital morbidity data can be used to estimate the incidence of serious chronic disease. However, incidence rates calculated from first-time hospital admissions tend to be overestimated as a result of the erroneous inclusion of prevalent cases that have had previous hospital admissions prior to the study observation period. To address this problem, we have developed the backcasting method. METHOD: A retrograde survival model was implemented to calculate the level of over-ascertainment of incidence according to the number of years of linked data on which the estimates were based and corresponding correction factors were calculated. The method is illustrated using the example of linked hospital morbidity data on diabetes mellitus and then acute myocardial infarction, which was validated against the Perth MONICA database for cardiovascular disease. RESULTS: Corrected estimates of the incidence of diabetes and acute myocardial infarction were produced. The incidence of diabetes was shown to be lower than in North America in accordance with prevalence estimates, whereas the incidence of acute myocardial infarction was overestimated by approximately 10%. CONCLUSION: A new method is presented for estimating incidence trends in disease from linked hospital morbidity data. The advantages of this method are its ease of use with routinely collected data and the relatively low cost of applying it in comparison with community surveys or maintaining formal disease registers. The method has other applications using linked data, such as the study of trends in first-time health care procedures and pharmaceutical prescriptions.

Estimation of excess risk of readmission to hospital after an index inpatient separation.

OBJECTIVES: To develop methods to measure excess risk of readmission following an index admission using linked administrative health data. RESEARCH DESIGN: The cumulative risk of readmission following an index admission was calculated for index and reference subjects using linked hospital morbidity, death, and electoral roll data in cohort, cohort-crossover, and cohort-comparison-crossover designs. SUBJECTS: Index subjects were defined as any man age 20 years or older who separated from an acute hospital in Western Australia in 1990 to 1995 following any form of prostatectomy for a principal diagnosis of benign prostatic hypertrophy. Reference subjects were selected from the general population and the electoral roll (cohort designs). Cases were also used as their own historical controls (cohort-crossover) with and without adjustment for background time difference (cohort-comparison-crossover). MEASURES: The excess risk of readmission following an index admission was estimated by calculating the cumulative risk of readmission in index subjects and subtracting the background risk of admission. The background risk calculation varied according to the study design. RESULTS: The risk of readmission at 30 days increased by 241 to 328% following the procedure. After 1 year of follow-up, the risk of readmission was still increased by 58 to 108%. In general, the absolute differences between index and reference subjects decrease or remain the same with increasing rigor of the methods. CONCLUSIONS: In this example, there was little difference between the cohort-crossover and the cohort-comparison-crossover designs, suggesting that the cohort-crossover method is a justifiable method in the absence of electoral roll controls.

Health outcomes in people with type 2 diabetes. A record linkage study.

INTRODUCTION: This study pilots a method of measuring health outcomes in a general practice population of patients with type 2 diabetes. METHOD: The Diabetic Register of the Perth and Osborne Divisions of General Practice was linked to the Western Australian Health Services Research Linked Database. RESULTS: Of the 487 patients in the study, 332 (68%) had been admitted before their diagnosis of diabetes (40% with a diabetes related condition), and 56% were admitted postdiagnosis (55% with a diabetes related condition). The admission rate increased with age and duration of diabetes. DISCUSSION: The data show that a large proportion of diabetic patients suffer from serious comorbidity both pre- and post-diagnosis and demonstrate that their hospital admission rate is higher than that in the general population. CONCLUSION: The project demonstrates that linked hospital morbidity data can be used to monitor health outcomes in a general practice population of diabetic patients.

Increasing 'active prevalence' of cancer in Western Australia and its implications for health services.

OBJECTIVE: To measure the active and total prevalence of cancer in Western Australia from 1990-98 and to examine trends in utilisation of hospital services by prevalent cancer patients. METHOD: Longitudinal analysis of linked cancer registrations, hospital separations and death registrations in Western Australia in 1990-98 using a population-based record linkage system. RESULTS: There was an estimated total of 53,450 patients ever-diagnosed with cancer in Western Australia at 30 June 1998 (29.7 per 1,000 population), an increase of 51% since mid-1990 (21.9/1,000). Patients with active disease accounted for 25% of the total prevalence, and the active prevalence of cancer increased from 5.1/1,000 in 1990 to 7.4/1,000 in 1998. In patients with active cancer, hospital admission rates for procedures other than chemotherapy and radiotherapy were stable or declining, but admission rates for chemotherapy and radiotherapy increased. The annual average cumulative length of stay decreased. CONCLUSIONS AND IMPLICATIONS: There has been a rapid increase in the number of prevalent patients requiring health care services for cancer during the 1990s. Most of the increase is due to improved survival, population growth and ageing. Further strain on Australian health care expenditure seems inevitable.