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2.  Cohort study of Western Australia computed tomography utilisation patterns and their policy implications 
Computed tomography (CT) scanning is a relatively high radiation dose diagnostic imaging modality with increasing concerns about radiation exposure burden at the population level in scientific literature. This study examined the epidemiology of adult CT utilisation in Western Australia (WA) in both the public hospital and private practice settings, and the policy implications.
Retrospective cohort design using aggregate adult CT data from WA public hospitals and Medical Benefits Schedule (MBS) (mid-2006 to mid-2012). CT scanning trends by sex, age, provider setting and anatomical areas were explored using crude CT scanning rates, age-standardised CT scanning rates and Poisson regression modelling.
From mid-2006 to mid-2012 the WA adult CT scanning rate was 129 scans per 1,000 person-years (PY). Females were consistently scanned at a higher rate than males. Patients over 65 years presented the highest scanning rates (over 300 scans per 1,000 PY). Private practice accounted for 73% of adult CT scans, comprising the majority in every anatomical area. In the private setting females predominately held higher age-standardised CT scanning rates than males. This trend reversed in the public hospital setting. Patients over 85 years in the public hospital setting were the most likely age group CT scanned in nine of ten anatomical areas. Patients in the private practice setting aged 85+ years were relatively less prominent across every anatomical area, and the least likely age group scanned in facial bones and multiple areas CT scans.
In comparison to the public hospital setting, the MBS subsidised private sector tended to service females and relatively younger patients with a more diverse range of anatomical areas, constituting the majority of CT scans performed in WA. Patient risk and subsequent burden is greater for females, lower ages and some anatomical areas. In the context of a national health system, Australia has various avenues to monitor radiation exposure levels, improve physician training and modify funding mechanisms to ensure individual and population medical radiation exposure is as low as reasonably achievable.
PMCID: PMC4226860  PMID: 25370909
Computed tomography; CT; Health service utilisation
3.  The Improving Rural Cancer Outcomes (IRCO) Trial: a factorial cluster-randomised controlled trial of a complex intervention to reduce time to diagnosis in rural patients with cancer in Western Australia: a study protocol 
BMJ Open  2014;4(9):e006156.
While overall survival for most common cancers in Australia is improving, the rural–urban differential has been widening, with significant excess deaths due to lung, colorectal, breast and prostate cancer in regional Australia. Internationally a major focus on understanding variations in cancer outcomes has been later presentation to healthcare and later diagnosis. Approaches to reducing time to diagnosis of symptomatic cancer include public symptom awareness campaigns and interventions in primary care to improve early cancer detection. This paper reports the protocol of a factorial cluster-randomised trial of community and general practice (GP) level interventions to reduce the time to diagnosis of cancer in rural Western Australia (WA).
Methods and analysis
The community intervention is a symptom awareness campaign tailored for rural Australians delivered through a community engagement model. The GP intervention includes a resource card with symptom risk assessment charts and local referral pathways implemented through multiple academic detailing visits and case studies. Participants are eligible if recently diagnosed with breast, colorectal, lung or prostate cancer who reside in specific regions of rural WA with a planned sample size of 1350. The primary outcome is the Total Diagnostic Interval, defined as the duration from first symptom (or date of cancer screening test) to cancer diagnosis. Secondary outcomes include cancer stage, healthcare utilisation, disease-free status, survival at 2 and 5 years and cost-effectiveness.
Ethics and dissemination
Ethics approval has been granted by the University of Western Australia and from all relevant hospital recruitment sites in WA.
Results of this trial will be reported in peer-reviewed publications and in conference presentations.
Trial registration number
Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN12610000872033.
PMCID: PMC4166137  PMID: 25231496
4.  A Study of Handling Cytotoxic Drugs and Risk of Birth Defects in Offspring of Female Veterinarians 
We examined the association of occupational exposure to handling cytotoxic drugs at work with risk of birth defects among a cohort of female veterinarians. This study is a follow up survey of 321 female participants (633 pregnancies) who participated in the Health Risks of Australian Veterinarian project. Data on pregnancies and exposure during each pregnancy was obtained by self-administered mailed questionnaire. Female veterinarians handling cytotoxic drugs during their pregnancy had a two-fold increased risk of birth defects in their offspring (RR = 2.08, 95% CI (1.05–4.15)). Results were consistent in subgroup analysis of those who graduated during the period of 1961 to 1980 (RR = 5.04, 95% CI (1.81, 14.03) and in those working specifically in small and large animal practice. There was no increased risk in the subgroup that graduated after 1980. Women with unplanned pregnancies were more likely to handle cytotoxic drugs on a daily basis (RR = 1.86, 95% CI, 1.00–3.48) and had a higher increased risk of birth defects than those who planned their pregnancies in recent graduates and in those who worked specifically in small animal practice (RR = 2.53, 95% CI, 1.18–5.42). This study suggests that the adverse effects of handling cytotoxic drugs in pregnant women may include an increased risk of birth defects. Pregnancy intention status is an important health behavior and should be considered in prenatal programs.
PMCID: PMC4078575  PMID: 24927037
cytotoxic drugs; birth defects; female veterinarians; unplanned pregnancy; cohort study; women health
5.  Women Commencing Anastrozole, Letrozole or Tamoxifen for Early Breast Cancer: The Impact of Comorbidity and Demographics on Initial Choice 
PLoS ONE  2014;9(1):e84835.
Australian clinical guidelines recommend endocrine therapy for all women with hormone-dependent early breast cancer. Guidelines specify tamoxifen as first-line therapy for pre-menopausal women, and tamoxifen or an aromatase inhibitor (AI) for post-menopausal women depending on the risk of recurrence based on tumour characteristics including size. Therapies have different side effect profiles; therefore comorbidity may also influence choice. We examined comorbidity, and the clinical and demographic characteristics of women commencing different therapies.
Patients and Methods
We identified the first dispensing of tamoxifen, anastrozole or letrozole for women diagnosed with invasive breast cancer in the 45 and Up Study from 2004–2009 (N = 1266). Unit-level pharmacy and medical service claims, hospital, Cancer Registry, and self-reported data were linked to determine menopause status at diagnosis, tumour size, age, comorbidities, and change in subsidy restrictions. Chi-square tests and generalised regression models were used to compare the characteristics of women commencing different therapies.
Most pre-menopausal women commenced therapy with tamoxifen (91%). Anastrozole was the predominant therapy for post-menopausal women (57%), followed by tamoxifen (28%). Women with osteoporosis were less likely to commence anastrozole compared with tamoxifen (anastrozole RR = 0.7, 95% CI = 0.5–0.9). Women with arthritis were 1.6-times more likely to commence letrozole than anastrozole (95% CI = 1.1–2.1). Tamoxifen was more often initiated in women with tumours >1 cm, who were also ≥75 years. Subsidy restriction changes were associated with substantial increases in the proportion of women commencing AIs (anastrozole RR = 4.3, letrozole RR = 8.3).
The findings indicate interplay of comorbidity and therapy choice for women with invasive breast cancer. Most post-menopausal women commenced therapy with anastrozole; however, letrozole and tamoxifen were more often initiated for women with comorbid arthritis and osteoporosis, respectively. Tamoxifen was also more common for women with tumours >1 cm and aged ≥75 years. Subsidy restrictions appear to have strongly influenced therapy choice.
PMCID: PMC3879327  PMID: 24392158
6.  Ascertaining invasive breast cancer cases; the validity of administrative and self-reported data sources in Australia 
Statutory State-based cancer registries are considered the ‘gold standard’ for researchers identifying cancer cases in Australia, but research using self-report or administrative health datasets (e.g. hospital records) may not have linkage to a Cancer Registry and need to identify cases. This study investigated the validity of administrative and self-reported data compared with records in a State-wide Cancer Registry in identifying invasive breast cancer cases.
Cases of invasive breast cancer recorded on the New South Wales (NSW) Cancer Registry between July 2004 and December 2008 (the study period) were identified for women in the 45 and Up Study. Registry cases were separately compared with suspected cases ascertained from: i) administrative hospital separations records; ii) outpatient medical service claims; iii) prescription medicines claims; and iv) the 45 and Up Study baseline survey. Ascertainment flags included diagnosis codes, surgeries (e.g. lumpectomy), services (e.g. radiotherapy), and medicines used for breast cancer, as well as self-reported diagnosis. Positive predictive value (PPV), sensitivity and specificity were calculated for flags within individual datasets, and for combinations of flags across multiple datasets.
Of 143,010 women in the 45 and Up Study, 2039 (1.4%) had an invasive breast tumour recorded on the NSW Cancer Registry during the study period. All of the breast cancer flags examined had high specificity (>97.5%). Of the flags from individual datasets, hospital-derived ‘lumpectomy and diagnosis of invasive breast cancer’ and ‘(lumpectomy or mastectomy) and diagnosis of invasive breast cancer’ had the greatest PPV (89% and 88%, respectively); the later having greater sensitivity (59% and 82%, respectively). The flag with the highest sensitivity and PPV ≥ 85% was 'diagnosis of invasive breast cancer' (both 86%). Self-reported breast cancer diagnosis had a PPV of 50% and sensitivity of 85%, and breast radiotherapy had a PPV of 73% and a sensitivity of 58% compared with Cancer Registry records. The combination of flags with the greatest PPV and sensitivity was ‘(lumpectomy or mastectomy) and (diagnosis of invasive breast cancer or breast radiotherapy)’ (PPV and sensitivity 83%).
In the absence of Cancer Registry data, administrative and self-reported data can be used to accurately identify cases of invasive breast cancer for sample identification, removing cases from a sample, or risk adjustment. Invasive breast cancer can be accurately identified using hospital-derived diagnosis alone or in combination with surgeries and breast radiotherapy.
PMCID: PMC3599953  PMID: 23399047
45 and up study; Sensitivity; Specificity; Positive predictive value; Lumpectomy; Mastectomy; Radiotherapy; Hospital diagnosis; Tamoxifen; Anastrazole; Self-report
7.  Cancer Survival and Excess Mortality Estimates among Adolescents and Young Adults in Western Australia, 1982–2004: A Population-Based Study 
PLoS ONE  2013;8(2):e55630.
Data are limited on cancer outcomes in adolescents and young adults.
Based on data from the Western Australian Data Linkage System, this study modelled survival and excess mortality in all adolescents and young adults aged 15–39 years in Western Australia who had a diagnosis of cancer in the period 1982–2004. Relative survival and excess all-cause mortality for all cancers combined and for principal tumour subgroups were estimated, using the Ederer II method and generalised linear Poisson modelling, respectively.
A cancer diagnosis in adolescents and young adults conferred substantial survival decrement. However, overall outcomes improved over calendar period (excess mortality hazard ratio [HR], latest versus earliest diagnostic period: 0.52, trend p<0.0001). Case fatality varied according to age group (HR, oldest versus youngest: 1.38, trend p<0.0001), sex (HR, female versus male: 0.66, 95% confidence interval [CI] 0.62–0.71), ethnicity (HR, Aboriginal versus others: 1.47, CI 1.23–1.76), geographical area (HR, rural/remote versus urban: 1.13, CI 1.04–1.23) and residential socioeconomic status (HR, lowest versus highest quartile: 1.14, trend p<0.05). Tumour subgroups differed substantially in frequency according to age group and sex, and were critical outcome determinants.
Marked progressive calendar-time improvement in overall outcomes was evident. Further research is required to disentangle the contributions of tumour biology and health service factors to outcome disparities between ethno-demographic, geographic and socioeconomic subgroups of adolescents and young adults with cancer.
PMCID: PMC3566059  PMID: 23405184
8.  Regular Primary Care Plays a Significant Role in Secondary Prevention of Ischemic Heart Disease in a Western Australian Cohort 
Journal of General Internal Medicine  2011;26(10):1092-1097.
Secondary prevention for established ischaemic heart disease (IHD) involves medication therapy and a healthier lifestyle, but adherence is suboptimal. Simply having scheduled regular appointments with a primary care physician could confer a benefit for IHD patients possibly through increased motivation and awareness, but this has not previously been investigated in the literature.
To estimate the association between regular general practitioner (GP) visitation and rates of all-cause death, IHD death or repeat hospitalisation for IHD in older patients in Western Australia (WA).
A retrospective cohort design.
Patients aged ≥ 65 years (n = 31,841) with a history of hospitalisation for IHD from 1992–2006 were ascertained through routine health data collected on the entire WA population and included in the analysis.
Main Measures
Frequency and regularity of GP visits was determined during a three-year exposure period at commencement of follow-up. A regularity score (range 0–1) measured the regularity of intervals between the GP visits and was divided into quartiles. Patients were then followed for a maximum of 11.5 years for outcome determination. Hazard ratios and 95% confidence intervals were calculated using Cox proportional hazards models.
Key Results
Compared with the least regular quartile, patients with greater GP visit regularity had significantly decreased risks of all-cause death (2nd least, 2nd most and most regular: HR = 0.76, 0.71 and 0.71); and IHD death (2nd least, 2nd most and most regular: HR = 0.70, 0.68 and 0.65). Patients in the 2nd least regular quartile also appeared to experience decreased risk of any repeat IHD hospitalisation (HR = 0.83, 95%CI 0.71–0.96) as well as emergency hospitalisation (HR = 0.81, 95%CI 0.67–0.98), compared with the least regular quartile.
Some degree of regular GP visitation offers a small but significant protection against morbidity and mortality in older people with established IHD. The findings indicate the importance of scheduled, regular GP visits for the secondary prevention of IHD.
PMCID: PMC3181311  PMID: 21347875
ischemic heart disease; hospitalisations; GP visits; record linkage; primary care
9.  Biologic markers of sun exposure and melanoma risk in women: pooled case-control analysis 
A model has been proposed whereby melanomas arise through two distinct pathways dependent upon the relative influence of host susceptibility and sun exposure. Such pathways may explain site-specific patterns of melanoma occurrence. To explore this model, we investigated the relationship between melanoma risk and general markers of acute (recalled sunburns) and chronic (prevalent solar keratoses) sun exposure, stratified by anatomic site and host phenotype. Our working hypothesis was that head and neck melanomas have stronger associations with solar keratoses and weaker associations with sunburn than trunk melanomas. We conducted a collaborative analysis using original data from women subjects of 11 case–control studies of melanoma (2575 cases, 3241 controls). We adjusted for potential confounding effects of sunlamp use and sunbathing. The magnitude of sunburn associations did not differ significantly by melanoma site, nevus count or histologic sub-type of melanoma. Across all sites, relative risk of melanoma increased with an increasing number of reported lifetime ‘painful’ sunburns, lifetime ‘severe’ sunburns and ‘severe’ sunburns in youth (ptrend<0.001), with pooled odds ratios for the highest category of sunburns vs no sunburns of 3.22 (95%CI 2.04–5.09) for lifetime ‘painful’ sunburns, 2.10 (95%CI 1.30–3.38) for lifetime ‘severe’ sunburns, and 2.43 (95%CI 1.61–3.65) for ‘severe’ sunburns in youth. Solar keratoses strongly increased the risk of head and neck melanoma (pOR 4.91, 95% CI 2.10–11.46), but data were insufficient to assess risk for other sites. Reported sunburn is strongly associated with melanoma on all major body sites.
PMCID: PMC3035752  PMID: 20857492
10.  Mental illness related disparities in diabetes prevalence, quality of care and outcomes: a population-based longitudinal study 
BMC Medicine  2011;9:118.
Health care disparity is a public health challenge. We compared the prevalence of diabetes, quality of care and outcomes between mental health clients (MHCs) and non-MHCs.
This was a population-based longitudinal study of 139,208 MHCs and 294,180 matched non-MHCs in Western Australia (WA) from 1990 to 2006, using linked data of mental health registry, electoral roll registrations, hospital admissions, emergency department attendances, deaths, and Medicare and pharmaceutical benefits claims. Diabetes was identified from hospital diagnoses, prescriptions and diabetes-specific primary care claims (17,045 MHCs, 26,626 non-MHCs). Both univariate and multivariate analyses adjusted for socio-demographic factors and case mix were performed to compare the outcome measures among MHCs, category of mental disorders and non-MHCs.
The prevalence of diabetes was significantly higher in MHCs than in non-MHCs (crude age-sex-standardised point-prevalence of diabetes on 30 June 2006 in those aged ≥20 years, 9.3% vs 6.1%, respectively, P < 0.001; adjusted odds ratio (OR) 1.40, 95% CI 1.36 to 1.43). Receipt of recommended pathology tests (HbA1c, microalbuminuria, blood lipids) was suboptimal in both groups, but was lower in MHCs (for all tests combined; adjusted OR 0.81, 95% CI 0.78 to 0.85, at one year; and adjusted rate ratio (RR) 0.86, 95% CI 0.84 to 0.88, during the study period). MHCs also had increased risks of hospitalisation for diabetes complications (adjusted RR 1.20, 95% CI 1.17 to 1.24), diabetes-related mortality (1.43, 1.35 to 1.52) and all-cause mortality (1.47, 1.42 to 1.53). The disparities were most marked for alcohol/drug disorders, schizophrenia, affective disorders, other psychoses and personality disorders.
MHCs warrant special attention for primary and secondary prevention of diabetes, especially at the primary care level.
PMCID: PMC3215928  PMID: 22044777
11.  The impact of mental illness on potentially preventable hospitalisations: a population-based cohort study 
BMC Psychiatry  2011;11:163.
Emerging evidence indicates an association between mental illness and poor quality of physical health care. To test this, we compared mental health clients (MHCs) with non-MHCs on potentially preventable hospitalisations (PPHs) as an indicator of the quality of primary care received.
Population-based retrospective cohort study of 139,208 MHCs and 294,180 matched non-MHCs in Western Australia from 1990 to 2006, using linked data from electoral roll registrations, mental health registry (MHR) records, hospital inpatient discharges and deaths. We used the electoral roll data as the sampling frame for both cohorts to enhance internal validity of the study, and the MHR to separate MHCs from non-MHCs. Rates of PPHs (overall and by PPH category and medical condition) were compared between MHCs, category of mental disorders and non-MHCs. Multivariate negative binomial regression analyses adjusted for socio-demographic factors, case mix and the year at the start of follow up due to dynamic nature of study cohorts.
PPHs accounted for more than 10% of all hospital admissions in MHCs, with diabetes and its complications, adverse drug events (ADEs), chronic obstructive pulmonary disease (COPD), convulsions and epilepsy, and congestive heart failure being the most common causes. Compared with non-MHCs, MHCs with any mental disorders were more likely to experience a PPH than non-MHCs (overall adjusted rate ratio (ARR) 2.06, 95% confidence interval (CI) 2.03-2.09). ARRs of PPHs were highest for convulsions and epilepsy, nutritional deficiencies, COPD and ADEs. The ARR of a PPH was highest in MHCs with alcohol/drug disorders, affective psychoses, other psychoses and schizophrenia.
MHCs have a significantly higher rate of PPHs than non-MHCs. Improving primary and secondary prevention is warranted in MHCs, especially at the primary care level, despite there may be different thresholds for admission in people with established physical disease that is influenced by whether or not they have comorbid mental illness.
PMCID: PMC3201897  PMID: 21985082
12.  Regular Primary Care Lowers Hospitalisation Risk and Mortality in Seniors with Chronic Respiratory Diseases 
Exacerbations in chronic respiratory diseases (CRDs) are sensitive to seasonal variations in exposure to respiratory infectious agents and allergens and patient factors such as non-adherence. Hence, regular general practitioner (GP) contact is likely to be important in order to recognise symptom escalation early and adjust treatment.
To examine the association of regularity of GP visits with all-cause mortality and first CRD hospitalisation overall and within groups of pharmacotherapy level in older CRD patients.
A retrospective cohort design using linked hospital, mortality, Medicare and pharmaceutical data for participant, exposure and outcome ascertainment. GP visit pattern was measured during the first 3 years of the observation period. Patients were then followed for a maximum of 11.5 years for ascertainment of hospitalisations and deaths.
We studied 108,455 patients aged ≥65 years with CRD in Western Australia (WA) during 1992–2006.
A GP visit regularity score (range 0–1) was calculated and divided into quintiles. A clinician consensus panel classified levels of pharmacotherapy. Cox proportional hazards models, controlling for multiple factors including GP visit frequency, were used to calculate hazard ratios and confidence intervals.
Differences in survival curves and hospital avoidance pattern between the GP visit regularity quintiles were statistically significant (p = 0.0279 and p < 0.0001, respectively). The protective association between GP visit regularity and death appeared to be confined to the highest pharmacotherapy level group (P for interaction = 0.0001). Higher GP visit regularity protected against first CRD hospitalisation compared with the least regular quintile regardless of pharmacotherapy level (medium regular: HR = 0.84, 95% CI = 0.77–0.92; 2nd most regular: HR = 0.74, 95% CI = 0.67–0.82; most regular HR = 0.77, 95% CI = 0.68–0.86).
The findings indicate that regular and proactive ‘maintenance’ primary care, as distinct from ‘reactive’ care, is beneficial to older CRD patients by reducing their risks of hospitalisation and death.
Electronic supplementary material
The online version of this article (doi:10.1007/s11606-010-1361-6) contains supplementary material, which is available to authorized users.
PMCID: PMC2896607  PMID: 20425147
chronic respiratory disease; mortality; hospitalisation; primary care; record linkage
13.  Mortality in Western Australian seniors with chronic respiratory diseases: a cohort study 
BMC Public Health  2010;10:385.
Relatively few studies have examined survival by pharmacotherapy level and the effects of patient characteristics on mortality by pharmacotherapy level in older chronic respiratory disease (CRD) patients. This study aimed to investigate these issues in older (≥ 65) CRD patients in Western Australia.
We identified 108,312 patients ≥ 65 years with CRD during 1992-2006 using linked medical, pharmaceutical, hospital and mortality databases held by the Commonwealth and State governments. Pharmacotherapy classification levels were designed by a clinical consensus panel. Cox regression was used to investigate the study aim.
Patients using only short acting bronchodilators experienced similar, but slightly worse survival than patients in the highest pharmacotherapy level group using high dose inhaled corticosteroids (ICS) ± long acting bronchodilators (LABs) ± oral steroids. Patients using low to medium dose ICS ± LABs experienced relatively better survival. Also, male gender was associated with all-cause mortality in all patients (HR = 1.72, 95% CI 1.65-1.80) and especially in those in the highest pharmacotherapy level group (HR = 1.97, 95%CI = 1.84-2.10). The P-value of interaction between gender and pharmacotherapy level for the effect on all-cause death was significant (0.0003).
Older patients with CRD not using ICS experienced the worst survival in this study and may benefit from an escalation in therapeutic regime. Males had a higher risk of death than females, which was more pronounced in the highest pharmacotherapy level group. Hence, primary health care should more actively direct disease management to mild-to-moderate disease patients.
PMCID: PMC2910678  PMID: 20591200
14.  Possible protective effect of green tea intake on risk of adult leukaemia 
British Journal of Cancer  2007;98(1):168-170.
In a case–control study of 107 adults with leukaemia and 110 orthopaedic controls in China, a reduced risk was found with longer duration, higher quantity, and frequency of green tea intake.
PMCID: PMC2359700  PMID: 18087282
adult leukaemia; case–control study; green tea; risk factor
15.  Comorbidity and repeat admission to hospital for adverse drug reactions in older adults: retrospective cohort study 
Objectives To identify factors that predict repeat admission to hospital for adverse drug reactions (ADRs) in older adults.
Design Population based retrospective cohort study.
Setting All public and private hospitals in Western Australia.
Participants 28 548 patients aged ≥60 years with an admission for an ADR during 1980-2000 followed for three years using the Western Australian data linkage system.
Results 5056 (17.7%) patients had a repeat admission for an ADR. Repeat ADRs were associated with sex (hazard ratio 1.08, 95% confidence interval 1.02 to 1.15, for men), first admission in 1995-9 (2.34, 2.00 to 2.73), length of hospital stay (1.11, 1.05 to 1.18, for stays ≥14 days), and Charlson comorbidity index (1.71, 1.46 to 1.99, for score ≥7); 60% of comorbidities were recorded and taken into account in analysis. In contrast, advancing age had no effect on repeat ADRs. Comorbid congestive cardiac failure (1.56, 1.43 to 1.71), peripheral vascular disease (1.27, 1.09 to 1.48), chronic pulmonary disease (1.61, 1.45 to 1.79), rheumatological disease (1.65, 1.41 to 1.92), mild liver disease (1.48, 1.05 to 2.07), moderate to severe liver disease (1.85, 1.18 to 2.92), moderate diabetes (1.18, 1.07 to 1.30), diabetes with chronic complications (1.91, 1.65 to 2.22), renal disease (1.93, 1.71 to 2.17), any malignancy including lymphoma and leukaemia (1.87, 1.68 to 2.09), and metastatic solid tumours (2.25, 1.92 to 2.64) were strong predictive factors. Comorbidities requiring continuing care predicted a reduced likelihood of repeat hospital admissions for ADRs (cerebrovascular disease 0.85, 0.73 to 0.98; dementia 0.62, 0.49 to 0.78; paraplegia 0.73, 0.59 to 0.89).
Conclusions Comorbidity, but not advancing age, predicts repeat admission for ADRs in older adults, especially those with comorbidities often managed in the community. Awareness of these predictors can help clinicians to identify which older adults are at greater risk of admission for ADRs and, therefore, who might benefit from closer monitoring.
PMCID: PMC2615549  PMID: 19129307
16.  The effects of socioeconomic status, accessibility to services and patient type on hospital use in Western Australia: a retrospective cohort study of patients with homogenous health status 
This study aimed to investigate groups of patients with a relatively homogenous health status to evaluate the degree to which use of the Australian hospital system is affected by socio-economic status, locational accessibility to services and patient payment classification.
Records of all deaths occurring in Western Australia from 1997 to 2000 inclusive were extracted from the WA mortality register and linked to records from the hospital morbidity data system (HMDS) via the WA Data Linkage System. Adjusted incidence rate ratios of hospitalisation in the last, second and third years prior to death were modelled separately for five underlying causes of death.
The independent effects of socioeconomic status on hospital utilisation differed markedly across cause of death. Locational accessibility was generally not an independent predictor of utilisation except in those dying from ischaemic heart disease and lung cancer. Private patient status did not globally affect utilisation across all causes of death, but was associated with significantly decreased utilisation three years prior to death for those who died of colorectal, lung or breast cancer, and increased utilisation in the last year of life in those who died of colorectal cancer or cerebrovascular disease.
It appears that the Australian hospital system may not be equitable since equal need did not equate to equal utilisation. Further it would appear that horizontal equity, as measured by equal utilisation for equal need, varies by disease. This implies that a 'one-size-fits-all' approach to further improvements in equity may be over simplistic. Thus initiatives beyond Medicare should be devised and evaluated in relation to specific areas of service provision.
PMCID: PMC1555582  PMID: 16774689
17.  Development of a health care policy characterisation model based on use of private health insurance 
The aim of this study was to develop a policy characterisation process based on measuring shifts in use of private health insurance (PHI) immediately following implementation of changes in federal health care policy.
Population-based hospital morbidity data from 1980 to 2001 were used to produce trend lines in the annual proportions of public, privately insured and privately uninsured hospital separations in age-stratified subgroups. A policy characterisation model was developed using visual and statistical assessment of the trend lines associated with changes in federal health care policy.
Of eight changes in federal health care policy, two (introduction of Medicare and Lifetime Health Cover) were directly associated with major changes in the trend lines; however, minor changes in trends were associated with several of the other federal policies. Three types of policy effects were characterised by our model: direction change, magnitude change and inhibition. Results from our model suggest that a policy of Lifetime Health Cover, with a sanction for late adoption of PHI, was immediately successful in changing the private: public mix. The desired effect of the 30% rebate was immediate only in the oldest age group (70+ years), however, introduction of the lifetime health cover and limitations in the model restricted the ability to determine whether or if the rebate had a delayed effect at younger ages.
An outcome-based policy characterisation model is useful in evaluating immediate effects of changes in health care policy.
PMCID: PMC1312311  PMID: 16274489
18.  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 
To demonstrate the use of end-quintile comparisons in assessing the effect of socio-economic status on hospital utilisation and outcomes in Western Australia.
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.
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.
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.
PMCID: PMC1236924  PMID: 16150153
19.  Patient-initiated switching between private and public inpatient hospitalisation in Western Australia 1980 – 2001: An analysis using linked data 
The aim of the study was to identify any distinct behavioural patterns in switching between public and privately insured payment classifications between successive episodes of inpatient care within Western Australia between 1980 and 2001 using a novel 'couplet' method of analysing longitudinal data.
The WA Data Linkage System was used to extract all hospital morbidity records from 1980 to 2001. For each individual, episodes of hospitalisation were paired into couplets, which were classified according to the sequential combination of public and privately insured episodes. Behavioural patterns were analysed using the mean intra-couplet interval and proportion of discordant couplets in each year.
Discordant couplets were consistently associated with the longest intra-couplet intervals (ratio to the average annual mean interval being 1.35), while the shortest intra-couplet intervals were associated with public concordant couplets (0.5). Overall, privately insured patients were more likely to switch payment classification at their next admission compared with public patients (the average rate of loss across all age groups being 0.55% and 2.16% respectively). The rate of loss from the privately insured payment classification was inversely associated with time between episodes (2.49% for intervals of 0 to 13 years and 0.83% for intervals of 14 to 21 years). In all age groups, the average rate of loss from the privately insured payment classification was greater between 1981 and 1990 compared with that between 1991 and 2001 (3.45% and 3.10% per year respectively).
A small but statistically significant reduction in rate of switching away from PHI over the latter period of observation indicated that health care policies encouraging uptake of PHI implemented in the 1990s by the federal government had some of their intended impact on behaviour.
PMCID: PMC1173079  PMID: 15978139
Data linkage; Health Policy; Health Insurance; Australia.
20.  Long term relative survival after surgery for abdominal aortic aneurysm in Western Australia: population based study 
BMJ : British Medical Journal  1998;317(7162):852-856.
Objective: To determine the long term relative survival of all patients who had surgery for abdominal aortic aneurysm in Western Australia during 1985-94.
Design: Population based study.
Setting: Western Australia.
Subjects: All patients who had had surgery for abdominal aortic aneurysm in Western Australia during 1985-94.
Main outcome measures: Morbidity and mortality data of patients admitted and surgically treated for abdominal aortic aneurysm in Western Australia during 1985-94. Elective, ruptured, and acute non-ruptured cases were analysed separately. Independent analyses for sex and patients aged 80 years or more were also undertaken. Postoperative (>30 days) relative survival was assessed against age and sex matched controls.
Results: Overall, 1475 (1257 men, 218 women) cases were identified. The crude five year survival after elective surgery, including deaths within 30 days of surgery, was 79% for both men and women. When compared with a matched population the five year relative survival after elective surgery was 94.9% (95% confidence interval 89.9% to 99.9%) for men but only 88.0% (76.3% to 99.7%) for women. The five year relative survival of those aged 80 years and over was good: 116.6% (89.1% to 144.0%) compared with 92.4% (87.7% to 97.0%) for those under 80 years of age (men and women combined). Cardiovascular disease caused 57.8% of the 341 deaths after 30 days.
Conclusion: In a condition such as abdominal aortic aneurysm, which occurs in elderly patients, relative survival is more clinically meaningful than crude survival. The five year relative survival in cases of elective and ruptured abdominal aortic aneurysm was better in men than in women. This is probably because of greater comorbidity in women with abdominal aortic aneurysm and this deserves more attention in the future. The long term survival outcome in octogenarians supports surgery in selected cases.
Key messages Background mortality for conditions such as abdominal aortic aneurysm in elderly patients needs to be taken into account when assessing long term survival after surgery Relative survival methodology can correct for background mortality The five year relative survival for patients surviving beyond 30 days of elective surgery for abdominal aortic aneurysm was 95% for men and 88% for women For octogenarians, five year survival after elective surgery was greater than that expected of an age matched population Age over 80 years should not preclude consideration for elective surgery for abdominal aortic aneurysm
PMCID: PMC31917  PMID: 9748177

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