Clinical outcomes and health care costs of transferring rural Western Australians for invasive coronary angiography, and a cost-effective alternative care model: a retrospective cross-sectional study

OBJECTIVES

To examine the severity of coronary artery disease (CAD) in people from rural or remote Western Australia referred for invasive coronary angiography (ICA) in Perth and their subsequent management; to estimate the cost savings were computed tomography coronary angiography (CTCA) offered in rural centres as a first line investigation for people with suspected CAD.

DESIGN

Retrospective cohort study.

SETTING, PARTICIPANTS

Adults with stable symptoms in rural and remote WA referred to Perth public tertiary hospitals for ICA evaluation during the 2019 calendar year.

MAIN OUTCOME MEASURES

Severity and management of CAD (medical management or revascularisation); health care costs by care model (standard care or a proposed alternative model with local CTCA assessment).

RESULTS

The mean age of the 1017 people from rural and remote WA who underwent ICA in Perth was 62 years (standard deviation, 13 years); 680 were men (66.9%), 245 were Indigenous people (24.1%). Indications for referral were non-ST elevation myocardial infarction (438, 43.1%), chest pain with normal troponin level (394, 38.7%), and other (185, 18.2%). After ICA assessment, 619 people were medically managed (60.9%) and 398 underwent revascularisation (39.1%). None of the 365 patients (35.9%) without obstructed coronaries (< 50% stenosis) underwent revascularisation; nine patients with moderate CAD (50-69% stenosis; 7%) and 389 with severe CAD (≥ 70% stenosis or occluded vessel; 75.5%) underwent revascularisation. Were CTCA used locally to determine the need for referral, 527 referrals could have been averted (53%), the ICA:revascularisation ratio would have improved from 2.6 to 1.6, and 1757 metropolitan hospital bed-days (43% reduction) and $7.3 million in health care costs (36% reduction) would have been saved.

CONCLUSION

Many rural and remote Western Australians transferred for ICA in Perth have non-obstructive CAD and are medically managed. Providing CTCA as a first line investigation in rural centres could avert half of these transfers and be a cost-effective strategy for risk stratification of people with suspected CAD.

Evidence-based medication adherence among seniors in the first year after heart failure hospitalisation and subsequent long-term outcomes: a restricted cubic spline analysis of adherence-outcome relationships

PURPOSE

Non-adherence to heart failure (HF) medications is associated with poor outcomes. We used restricted cubic splines (RCS) to assess the continuous relationship between adherence to renin-angiotensin system inhibitors (RASI) and β-blockers and long-term outcomes in senior HF patients.

METHODS

We identified a population-based cohort of 4234 patients, aged 65-84 years, 56% male, who were hospitalised for HF in Western Australia between 2003 and 2008 and survived to 1-year post-discharge (landmark date). Adherence was calculated using the proportion of days covered (PDC) in the first year post-discharge. RCS Cox proportional-hazards models were applied to determine the relationship between adherence and all-cause death and death/HF readmission at 1 and 3 years after the landmark date.

RESULTS

RCS analysis showed a curvilinear adherence-outcome relationship for both RASI and β-blockers which was linear above PDC 60%. For each 10% increase in RASI and β-blocker adherence above this level, the adjusted hazard ratio for 1-year all-cause death fell by an average of 6.6% and 4.8% respectively (trend p < 0.05) and risk of all-cause death/HF readmission fell by 5.4% and 5.8% respectively (trend p < 0.005). Linear reductions in adjusted risk for these outcomes at PDC ≥ 60% were also seen at 3 years after landmark date (all trend p < 0.05).

CONCLUSION

RCS analysis showed that for RASI and β-blockers, there was no upper adherence level (threshold) above 60% where risk reduction did not continue to occur. Therefore, interventions should maximise adherence to these disease-modifying HF pharmacotherapies to improve long-term outcomes after hospitalised HF.

Temporal trends in myocardial infarction case fatality: methodological challenges and prevention targets

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Health and Medical Research Council of AustraliaHealy Medical Research Foundation

Background

Case fatality is an important indicator of severity and quality of care for myocardial infarction (MI). Most studies focus on hospitalised case fatality, which does not capture the total burden of MI deaths. Additionally, changes in diagnostic criteria and acute clinical care, and evidence that identifying all coronary heart disease (CHD) events better captures this patient group,1 have led to suggestions that a different definition of case fatality is required.

Purpose

The aim of the study was to determine the impact of different definitions of case fatality on the composition of fatal cases, and to measure trends in case fatality across a range of case definitions.

Methods

A whole-state linked hospital/death dataset was used to identify all MI, acute coronary syndromes (ACS) and CHD events (fatal + nonfatal) from 1997-2015. The traditional MI case fatality definition included all MI deaths as the numerator, stratified as MI hospitalisation with death ≤28 days, non-MI hospitalisation with MI death ≤28 days, or pre-hospital MI deaths. The denominator was all MIs (fatal plus nonfatal MI). ACS and a broader CHD definition were trialled, with ACS or CHD deaths as the numerator respectively, stratified in a similar manner as MI. Case fatality was age-standardised by 5-year age group using the internal age distribution of each definition as the standard.

Results

From 1997 to 2015, there were 76,928 MI events, 126,470 ACS events, and 235,100 CHD events. Of the MI cohort, 64.1% were men, and 13.0% had a prior MI, with a similar pattern in the ACS and CHD cohorts. For the traditional definition of MI case fatality, 10,819 deaths (53.9%) occurred pre-hospital, 4990 deaths in those hospitalised for MI and dying ≤28 days (24.8%), and 4271 MI deaths (21.3%) ≤28 days of a non-MI hospitalisation (Figure). Using the broadest CHD definition of case fatality, there was a similar proportion of pre-hospital deaths, but a higher proportion of CHD deaths in those with a non-CHD hospitalisation.

In men, age-standardised MI case fatality declined from 40.0% in 1997 to 17.3% by 2015; in women, the decline was from 41.9% to 18.2%. In contrast, using the ACS and broad CHD definitions, age-standardised case fatality was lower than for MI throughout the study period, with a smaller temporal decline (ACS: men 22.2% to 13.1%, women 20.5% to 13.0%; CHD: men 20.6% to 12.4%, women 19.3% to 12.3%).

Conclusion

Despite substantial falls in MI case fatality, the fatal burden remains high. Regardless of the case fatality definition, pre-hospital deaths from acute or all CHD have remained high over time, highlighting the need to target the pre-hospital setting. Caution is needed when using different definitions of case fatality to ensure relevant statistics are used, particularly for temporal trends.

Figure Legend. Proportion of MI deaths occurring ≤28 days after MI hospitalisation (2), ≤28 days after non-MI hospitalisation (3), and pre-hospital (4).

Incidence, predictors and mortality risk of new heart failure in patients hospitalised with atrial fibrillation

OBJECTIVE

To determine the incidence, risk predictors and relative mortality risk of incident heart failure (HF) in patients following atrial fibrillation (AF) hospitalisation.

METHODS

The Western Australian Hospitalisation Morbidity Data Collection was used to identify patients aged 25-94 years with index (first-in-period) AF hospitalisation, but without a prior HF admission, between 2000 and 2013. We evaluated the risk of incident HF hospitalisation within 3 years after AF admission, and the impact of HF hospitalisation on all-cause mortality.

RESULTS

The cohort comprised 52 447 patients, 57.5% men, with a median age of 73.1 (IQR 63.2-80.8) years. At 3 years after AF discharge, the cumulative incidence of HF (n=6153) was 11.7% (95% CI 11.5% to 12.0%) and all-cause death (n=9702) was 18.5% (95% CI 18.2% to 18.8%). Independent predictors of incident HF included advancing age, any history of myocardial infarction (MI), peripheral vascular disease, valvular heart disease, chronic kidney disease, chronic obstructive pulmonary disease, hypertension, diabetes, obesity and excessive alcohol use (all p<0.001). Patients hospitalised for first-ever HF compared with those without HF hospitalisation had an adjusted HR of 3.3 (95% CI 3.1 to 3.4) for all-cause mortality (p<0.001). Independent predictors of HF were also shared with those for mortality, with the exception of hypertension.

CONCLUSION

Hospitalisation for new HF is common in patients with AF and independently associated with a 3-fold hazard for death. The clinical predictors of incident HF emphasise the importance of integrated management of common comorbid conditions and lifestyle risk factors in patients with AF to reduce their morbidity and mortality.

Single high-sensitivity troponin levels to assess patients with potential acute coronary syndromes

OBJECTIVE

We tested the hypothesis that patients with a potential acute coronary syndrome (ACS) and very low levels of high-sensitivity cardiac troponin I can be efficiently and safely discharged from the emergency department after a single troponin measurement.

METHODS

This prospective cohort study recruited 2255 consecutive patients aged ≥18 years presenting to the Emergency Department, Royal Perth Hospital, Western Australia, with chest pain without high-risk features but requiring the exclusion of ACS. Patients were managed using a guideline-recommended pathway or our novel Single Troponin Accelerated Triage (STAT) pathway. The primary outcome was the percentage of patients discharged in <3 hours. Secondary outcomes included the duration of observation and death or acute myocardial infarction in the next 30 days.

RESULTS

The study enrolled 1131 patients to the standard cohort and 1124 to the STAT cohort. Thirty-eight per cent of the standard cohort were discharged directly from emergency department compared with 63% of the STAT cohort (p<0.001). The median duration of observation was 4.3 (IQR 3.3-7.1) hours in the standard cohort and 3.6 (2.6-5.4) hours in the STAT cohort (p<0.001), with 21% and 38% discharged in <3 hours, respectively (p<0.001). No patients discharged directly from the emergency department died or suffered an acute myocardial infarction within 30 days in either cohort.

CONCLUSIONS

Among low-risk patients with a potential ACS, a pathway which incorporates early discharge based on a single very low level of high-sensitivity cardiac troponin increases the proportion of patients discharged directly from the emergency department, reduces length of stay and is safe.

TRIAL REGISTRATION NUMBER

ACTRN12618000797279.

Invasive Coronary Angiography after Chest Pain Presentations to Emergency Departments

We investigated patients presenting to emergency departments (EDs) with chest pain to identify factors that influence the use of invasive coronary angiography (ICA). Using linked ED, hospitalisations, death and cardiac biomarker data, we identified people aged 20 years and over who presented with chest pain to tertiary public hospital EDs in Western Australia from 1 January 2016 to 31 March 2017 (ED chest pain cohort). We report patient characteristics, ED discharge diagnosis, pathways to ICA, ICA within 90 days, troponin test results, and gender differences. Associations were examined with the Pearson Chi-squared test and multivariate logistic regression. There were 16,974 people in the ED chest pain cohort, with a mean age of 55.6 years and 50.7% males, accounting for 20,131 ED presentations. Acute coronary syndrome was the ED discharge diagnosis in 10.4% of presentations. ED pathways were: discharged home (57.5%); hospitalisation (41.7%); interhospital transfer (0.4%); and died in ED (0.03%)/inpatients (0.3%). There were 1546 (9.1%) ICAs performed within 90 days of the first ED chest pain visit, of which 59 visits (3.8%) had no troponin tests and 565 visits (36.6%) had normal troponin. ICAs were performed in more men than women (12.3% vs. 6.1%, p < 0.0001; adjusted OR 1.89, 95% CI 1.65, 2.18), and mostly within 7 days. Equal numbers of males and females present with chest pain to tertiary hospital EDs, but men are twice as likely to get ICA. Over one-third of ICAs occur in those with normal troponin levels, indicating that further investigation is required to determine risk profile, outcomes and cost effectiveness.

Evaluating recruitment strategies for AUSPICE, a large Australian community-based randomised controlled trial

OBJECTIVES

To examine the effectiveness of different strategies for recruiting participants for a large Australian randomised controlled trial (RCT), the Australian Study for the Prevention through Immunisation of Cardiovascular Events (AUSPICE).

DESIGN, SETTING, PARTICIPANTS

Men and women aged 55-60 years with at least two cardiovascular risk factors (hypertension, hypercholesterolaemia, overweight/obesity) were recruited for a multicentre placebo-controlled RCT assessing the effectiveness of 23-valent pneumococcal polysaccharide vaccine (23vPPV) for preventing cardiovascular events.

METHODS

Invitations were mailed by the Australian Department of Human Services to people in the Medicare database aged 55-60 years; reminders were sent 2 weeks later. Invitees could respond in hard copy or electronically. Direct recruitment was supplemented by asking invitees to extend the invitation to friends and family (snowball sampling) and by Facebook advertising.

MAIN OUTCOME

Proportions of invitees completing screening questionnaire and recruited for participation in the RCT.

RESULTS

21 526 of 154 992 invited people (14%) responded by completing the screening questionnaire, of whom 4725 people were eligible and recruited for the study. Despite the minimal study burden (one questionnaire, one clinic visit), the overall participation rate was 3%, or an estimated 10% of eligible persons. Only 16% of eventual participants had responded within 2 weeks of the initial invitation letter (early responders); early and late responders did not differ in their demographic or medical characteristics. Socio-economic disadvantage did not markedly influence response rates. Facebook advertising and snowball sampling did not increase recruitment.

CONCLUSIONS

Trial participation rates are low, and multiple concurrent methods are needed to maximise recruitment. Social media strategies may not be successful in older age groups.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12615000536561.

Operationalization and validation of a novel method to calculate adherence to polypharmacy with refill data from the Australian pharmaceutical benefits scheme (PBS) database

Background

Electronic health care data contain rich information on medicine use from which adherence can be estimated. Various measures developed with medication claims data called for transparency of the equations used, predominantly because they may overestimate adherence, and even more when used with multiple medications. We aimed to operationalize a novel calculation of adherence with polypharmacy, the daily polypharmacy possession ratio (DPPR), and validate it against the common measure of adherence, the medication possession ratio (MPR) and a modified version (MPR_m).

Methods

We used linked health data from the Australian Pharmaceutical Benefits Scheme and Western Australian hospital morbidity dataset and mortality register. We identified a strict study cohort from 16,185 patients aged ≥65 years hospitalized for myocardial infarction in 2003–2008 in Western Australia as an illustrative example. We applied iterative exclusion criteria to standardize the dispensing histories according to previous literature. A SAS program was developed to calculate the adherence measures accounting for various drug parameters.

Results

The study cohort was 348 incident patients (mean age 74.6±6.8 years; 69% male) with an admission for myocardial infarction who had cardiovascular medications over a median of 727 days (range 74 to 3,798 days) prior to readmission. There were statins (96.8%), angiotensin converting enzyme inhibitors (88.8%), beta-blockers (85.6%), and angiotensin receptor blockers (13.2%) dispensed. As expected, observed adherence values were higher with mean MPR (median 89.2%; Q₁: 73.3%; Q_3: 104.6%) than mean MPR_m (median 82.8%; Q₁: 68.5%; Q_3: 95.9%). DPPR values were the most narrow (median 83.8%; Q₁: 70.9%; Q_3: 96.4%). Mean MPR and DPPR yielded very close possession values for 37.9% of the patients. Values were similar in patients with longer observation windows. When the traditional threshold of 80% was applied to mean MPR and DPPR values to signify the threshold for good adherence, 11.6% of patients were classified as good adherers with the mean MPR relative to the DPPR.

Conclusion

In the absence of transparent and standardized equations to calculate adherence to polypharmacy from refill databases, the novel DPPR algorithm represents a valid and robust method to estimate medication possession for multi-medication regimens.

National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand: Australian clinical guidelines for the management of acute coronary syndromes 2016

INTRODUCTION

The modern care of suspected and confirmed acute coronary syndrome (ACS) is informed by an extensive and evolving evidence base. This clinical practice guideline focuses on key components of management associated with improved clinical outcomes for patients with chest pain or ACS. These are presented as recommendations that have been graded on both the strength of evidence and the likely absolute benefit versus harm. Additional considerations influencing the delivery of specific therapies and management strategies are presented as practice points.

MAIN RECOMMENDATIONS

This guideline provides advice on the standardised assessment and management of patients with suspected ACS, including the implementation of clinical assessment pathways and subsequent functional and anatomical testing. It provides guidance on the: diagnosis and risk stratification of ACS; provision of acute reperfusion therapy and immediate post-fibrinolysis care for patients with ST segment elevation myocardial infarction; risk stratification informing the use of routine versus selective invasive management for patients with non-ST segment elevation ACS; administration of antithrombotic therapies in the acute setting and considerations affecting their long term use; and implementation of an individualised secondary prevention plan that includes both pharmacotherapies and cardiac rehabilitation. Changes in management as a result of the guideline: This guideline has been designed to facilitate the systematic integration of the recommendations into a standardised approach to ACS care, while also allowing for contextual adaptation of the recommendations in response to the individual's needs and preferences. The provision of ACS care should be subject to continuous monitoring, feedback and improvement of quality and patient outcomes.

Variation in coronary angiography rates in Australia: correlations with socio-demographic, health service and disease burden indices

BACKGROUND

Variation in the provision of coronary angiography is associated with health care inefficiency and inequity. We explored geographic, socio-economic, health service and disease indicators associated with variation in angiography rates across Australia.

METHODS

Australian census and National Health Survey data were used to determine socio-economic, health workforce and service indicators. Hospital separations and coronary deaths during 2011 were identified in the National Hospital Morbidity and Mortality databases. All 61 Medicare Locals responsible for primary care were included, and age- and sex-standardised rates of acute coronary syndrome (ACS) incidence, coronary angiography, revascularisation and mortality were tested for correlations, and adjusted by Bayesian regression.

RESULTS

There were 3.7-fold and 2.3-fold differences between individual Medicare Locals in the lowest and highest ACS and coronary artery disease mortality rates respectively, whereas angiography rates varied 5.3-fold. ACS and death rates within Medicare Locals were correlated (partial correlation coefficient [CC], 0.52; P < 0.001). There was modest correlation between ACS and angiography rates (CC, 0.31; P = 0.018). The proportion of patients undergoing angiography who proceeded to revascularisation was inversely correlated with the total angiogram rate (CC, -0.71; P < 0.001). Socio-economic disadvantage and remoteness were correlated with disease burden, ACS incidence and mortality, but not with angiography rate. In the adjusted analysis, the strongest association with local angiography rates was with admissions to private hospitals (71 additional angiograms [95% CI, 47-93] for every 1000 admissions).

CONCLUSION

Variation in rates of coronary angiography, not related to clinical need, occurs across Australia. A greater focus on clinical care standards and better distribution of health services will be required if these variations are to be attenuated.

National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand: Australian clinical guidelines for the management of acute coronary syndromes 2016

INTRODUCTION

The modern care of suspected and confirmed acute coronary syndrome (ACS) is informed by an extensive and evolving evidence base. This clinical practice guideline focuses on key components of management associated with improved clinical outcomes for patients with chest pain or ACS. These are presented as recommendations that have been graded on both the strength of evidence and the likely absolute benefit versus harm. Additional considerations influencing the delivery of specific therapies and management strategies are presented as practice points.

MAIN RECOMMENDATIONS

This guideline provides advice on the standardised assessment and management of patients with suspected ACS, including the implementation of clinical assessment pathways and subsequent functional and anatomical testing. It provides guidance on the: diagnosis and risk stratification of ACS; provision of acute reperfusion therapy and immediate post-fibrinolysis care for patients with ST segment elevation myocardial infarction; risk stratification informing the use of routine versus selective invasive management for patients with non-ST segment elevation ACS; administration of antithrombotic therapies in the acute setting and considerations affecting their long term use; and implementation of an individualised secondary prevention plan that includes both pharmacotherapies and cardiac rehabilitation. Changes in management as a result of the guideline: This guideline has been designed to facilitate the systematic integration of the recommendations into a standardised approach to ACS care, while also allowing for contextual adaptation of the recommendations in response to the individual's needs and preferences. The provision of ACS care should be subject to continuous monitoring, feedback and improvement of quality and patient outcomes.

Secondary preventive medication use in a prevalent population-based cohort of acute coronary syndrome survivors

AIM

Describe the dispensing patterns for guideline-recommended medications during 2008 in people with acute coronary syndrome (ACS) and how dispensing varies by gender and time since last ACS hospitalization.

METHOD

A descriptive cohort spanning 20 years of people alive post-ACS in 2008. We extracted all ACS hospitalizations and deaths in Western Australia (1989-2008), and all person-linked Pharmaceutical Benefits Scheme claims nationally for 2008. Participants were 23 642 men and women (36.8%), alive and aged 65-89 years in mid-2008 who were hospitalized for ACS between 1989 and 2008. Main outcome was the proportion of the study cohort (in 2008) dispensed guideline-recommended cardiovascular medications in that year. Adjusted odds ratios estimating the association between type (and number) of guideline-recommended medications and time since last ACS hospitalization.

RESULTS

Medications most commonly dispensed in 2008 were statins (79.6% of study cohort) and then angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (ACEi/ARBs) (71.1%), aspirin or clopidogrel (59.4%), and β-blockers (54.6%). Only 51.8% of the cohort was dispensed three or more of these drug types in 2008. Women with ACS were 18% less likely to be dispensed statins (adjusted odds ratio (OR)=0.82; 95% CI 0.76-0.88). Overall, for each incremental year since last ACS admission, there was an 8% increased odds (adjusted OR=1.08; 95% CI 1.07-1.08) of being dispensed fewer of the recommended drug regimen in 2008.

CONCLUSION

Longer time since last ACS admission was associated with dispensing fewer medications types and combinations in 2008. Interventions are warranted to improve dispensing long term and any apparent gender inequality in the drug class filled.

Is the incidence of heart attack still decreasing in Australia? Developing reliable methods for monitoring trends in myocardial infarction and coronary heart disease (AUS-MOCHA): a study protocol

INTRODUCTION

Accurate monitoring of acute coronary heart disease (CHD) is essential for understanding the effects of primary and secondary prevention and for planning of healthcare services. The ability to reliably monitor acute CHD has been affected by new diagnostic tests for myocardial infarction (MI) and changing clinical classifications and management of CHD. Our study will develop new and reliable methods for monitoring population trends in incidence, outcomes and health service usage for acute CHD and chest pain.

METHODS AND ANALYSIS

The study cohort of all CHD will be identified from the Western Australian Data Linkage System using state-wide data sets for emergency department presentation, hospitalisations and mortality data for 2002-2014. This core linked data set will be supplemented with data from hospital medical record reviews, pathology data and hospital pharmacy dispensing databases. The consistency over time of the coding of the different subgroups of CHD/chest pain (ST-elevation MI, non-ST elevation MI, unstable angina, stable angina, other CHD, non-CHD chest pain) in linked data will be assessed using these data sources, and an algorithm developed detailing groups in which temporal trends can be reliably measured. This algorithm will be used for measurement of trends in incidence and outcomes of acute CHD, and to develop further methods for monitoring acute CHD using unlinked and linked data with varying availability of hospitalisation history.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Human Research Ethics Committees of the WA Department of Health (#2016/23) and The University of Western Australia (RA/4/1/7230). Findings will be disseminated via publication in peer-reviewed journals, and presentation at national and international conferences. There will also be a strong platform for dissemination of new monitoring methods via collaboration with the Australian Institute of Health and Welfare which will assist with promotion of these methods at state and national levels.

Long-term all-cause and cardiovascular mortality following incident myocardial infarction in men and women with and without diabetes: Temporal trends from 1998 to 2009

BACKGROUND

Long-term mortality following myocardial infarction is higher in diabetic than non-diabetic individuals. Early case-fatality after myocardial infarction has improved but it is unclear whether trends extend to long-term mortality. We aimed to determine whether the disparity in long-term all-cause and cardiovascular disease mortality by diabetes status has decreased.

METHODS

All incident myocardial infarction cases were identified from Western Australian whole-population linked data for 1998-2009. Mortality follow-up was available until 30 June 2011. Unadjusted survival was estimated using Kaplan-Meier survival curves. Hazard ratios comparing five-year mortality in diabetic versus non-diabetic people across three periods (1998-2001, 2002-2005, 2006-2009) were estimated from multivariable Cox regression models, and adjusted trends calculated from interaction (diabetes status × period) models.

RESULTS

There were 22,594 30-day survivors of incident MI. There was little change across the three periods in all-cause mortality in diabetic men (27.1%, 28.2%, 25.5%) and women (34.9%, 36.8%, 36.1%), but small declines from first to last periods in non-diabetic men (14.5% to 12.1%, p = 0.03) and women (21.0% to 19.4%, p = 0.08). There was no temporal change in the increased all-cause mortality hazard ratios in diabetic versus non-diabetic men and women. Multivariable-adjusted relative risk for cardiovascular disease mortality remained elevated in diabetic women (2006-2009 hazard ratio 1.73, 95% confidence interval 1.29, 2.32) but not in men (2006-2009 hazard ratio 1.08, 95% confidence interval 0.85, 1.37).

CONCLUSIONS

The excess long-term mortality associated with diabetes and excess cardiovascular disease mortality in diabetic women indicates a need for improved secondary prevention in diabetic patients, especially women.

Survival after an acute coronary syndrome: 18-month outcomes from the Australian and New Zealand SNAPSHOT ACS study

OBJECTIVES

To assess the impact of the availability of a catheterisation laboratory and evidence-based care on the 18-month mortality rate in patients with suspected acute coronary syndromes (ACS).

DESIGN, SETTING AND PARTICIPANTS

Management and outcomes are described for patients enrolled in the 2012 Australian and New Zealand SNAPSHOT ACS audit. Patients were stratified according to their presentation to hospitals with or without cardiac catheterisation facilities. Data linkage ascertained patient vital status 18 months after admission. Descriptive and Cox proportional hazards analyses determined predictors of outcomes, and were used to estimate the numbers of deaths that could be averted by improved application of evidence-based care.

MAIN OUTCOME MEASURES

Mortality for ACS patients from admission to 18 months after admission.

RESULTS

Definite ACS patients presenting to catheterisation-capable (CC) hospitals (n = 1326) were more likely to undergo coronary angiography than those presenting to non-CC hospitals (n = 1031) (61.5% v 50.8%; P = 0.0001), receive timely reperfusion (for ST elevation myocardial infarction (STEMI) patients: 45.2% v 19.2%; P < 0.001), and be referred for cardiac rehabilitation (57% v 53%; P = 0.05). All-cause mortality over 18 months was highest for STEMI (16.2%) and non-STEMI (16.3%) patients, and lowest for those presenting with unstable angina (6.8%) and non-cardiac chest pain (4.8%; P < 0.0001 for trend). After adjustment for patient propensity to present to a CC hospital and patient risk, presentation to a CC hospital was associated with 21% (95% CI, 2%-37%) lower mortality than presentation to a non-CC hospital. This mortality difference was attenuated after adjusting for delivery of evidence-based care.

CONCLUSION

In Australia and New Zealand, the availability of a catheterisation laboratory appears to have a significant impact on long-term mortality in ACS patients, which is still substantial. This mortality may be reduced by improvements in evidence-based care in both CC and non-CC hospitals.

Improving 30-day case fatality after incident myocardial infarction in people with diabetes between 1998 and 2010

OBJECTIVE

To compare population-level trends in 30-day case fatality following incident myocardial infarction (MI) in people with diabetes and those without diabetes.

METHODS

We identified all hospitalised incident MIs in 35-84 year olds from the Western Australian Data Linkage System for 1998-2010, stratified by diabetes status. Crude and age- and sex-standardised 30-day case fatality were estimated, and age- and sex-adjusted trends were calculated from logistic regression. We calculated the trend in risk of 30-day death associated with diabetes from multivariable logistic regression, adjusting for demographics, comorbidities and MI type.

RESULTS

26 610 hospitalised incident MI cases were identified, 24.8% of whom had diabetes. The prevalence of heart failure fell in people with diabetes, concurrent with increasing chronic kidney disease and prior coronary heart disease and increasing levels of evidence-based therapies. Case fatality in people with diabetes fell from 11.65%, in 1998-2001, to 3.96% by 2008-2010. Age- and sex-standardised case fatality declined at a greater rate in those with diabetes (-10.6%/year, 95% CI -12.8% to -8.2%) compared to non-diabetics (-6.9%/year, 95% CI -8.3% to -5.3%; interaction p=0.005). The adjusted risk of 30-day death after incident MI was 1.23 times higher in diabetics than non-diabetics in 1998-2001 (95% CI 1.01 to 1.50), but was lower by 2008-2010 (OR 0.64, 95% CI 0.46 to 0.88).

CONCLUSIONS

Greater improvements in 30-day case fatality following incident MI in people with diabetes during the 13-year study period has led to diabetes no longer being an independent predictor of early death following incident MI by 2008-2010.

Availability of highly sensitive troponin assays and acute coronary syndrome care: insights from the SNAPSHOT registry

OBJECTIVES

To examine differences in care and inhospital course of patients with possible acute coronary syndrome (ACS) in Australia and New Zealand based on whether a highly sensitive (hs) troponin assay was used at the hospital to which they presented.

DESIGN, SETTING AND PATIENTS

A snapshot study of consecutive patients presenting to hospitals in Australia and New Zealand from 14 to 27 May 2012 with possible ACS.

MAIN OUTCOME MEASURES

Rates of major adverse cardiac events (inhospital death, new or recurrent myocardial infarction, stroke, cardiac arrest or worsening heart failure); association between assay type and outcome (via propensity score matching and a generalised estimating equation [GEE]; averages of the predicted outcomes among patients who were treated with and without the availability of an hs assay (via inverse probability-weighting [IPW] with regression-adjusted estimators).

RESULTS

4371 patients with possible ACS were admitted to 283 hospitals. Over half of the hospitals (156 [55%]) reported using the hs assay and most patients (2624 [60%]) had hs tests (P = 0.004). Use of the hs assay was independent of hospital coronary revascularisation capability. Patients tested with the hs assay had more non-invasive investigations (exercise tests, stress echocardiography, stress nuclear scans, and computed tomography coronary angiography) than those tested with the sensitive assay. However, there were no differences between the groups in rates of angiography or revascularisation. All adjusted analyses showed a consistently lower rate of inhospital events, including recurrent heart failure in patients for whom the hs assay was used (GEE odds ratio, 0.75; 95% CI, 0.60-0.94; P = 0.014); IPW analysis showed a 2.3% absolute reduction in these events with the use of the hs assay (P = 0.018).

CONCLUSION

Use of hs troponin testing of patients hospitalised with possible ACS was associated with an increased rate of non-invasive cardiac investigations and fewer inhospital adverse events.

Temporal trends in initial and recurrent lower extremity amputations in people with and without diabetes in Western Australia from 2000 to 2010

AIMS

To examine temporal trends in lower extremity amputations in people with type 1 diabetes, type 2 diabetes and cardiovascular disease (CVD) without diabetes in Western Australia (WA) from 2000 to 2010.

METHODS

We used linked health data to identify all non-traumatic lower extremity amputations in adults aged ≥20 years with diabetes and/or CVD from 2000 to 2010 in WA. Annual age- and sex-standardised rates of total, initial and recurrent amputations, stratified by major and minor status, were calculated for type 1 and type 2 diabetes, and CVD without diabetes, from the at-risk population for each group. Age- and sex-adjusted trends were estimated from Poisson regression models.

RESULTS

5891 lower extremity amputations were identified. Peripheral vascular disease (71%), hypertension (70%) and chronic kidney disease (60%) were highly prevalent. Average annual rates of total amputations were 724, 564 and 66 per 100,000 person-years in type 1, type 2 diabetes and CVD without diabetes respectively. Rates of initial amputations fell significantly by 2.4%/year (95% CI -3.5, -1.4) in type 2 diabetes, with similar declines for type 1 diabetes and CVD without diabetes (interaction p=0.96), driven by large falls in major amputations. There was limited improvement in recurrence rates overall, with recurrent minor amputations increasing significantly in type 2 diabetes (+3.5%/year, 95% CI +1.3%, +5.7%).

CONCLUSION

Lower extremity amputation rates have declined at a population level in people with diabetes and CVD without diabetes, suggesting improvements in prevention and management for this high-risk patient group, however limited declines in recurrent amputations requires further investigation.

Using quality indicators to compare outcomes of permanent cardiac pacemaker implantation among publicly and privately funded patients

BACKGROUND

Funding source/insurance status has been associated with disparity in the management and outcomes of cardiovascular disease, with poorer outcomes among disadvantaged groups.

AIM

Using proposed quality indicators for permanent pacemaker (PPM) implantation and administrative data, this study aimed to determine whether quality indicator-based outcomes of PPM implantation were comparable for publicly and privately funded patients within Australia's two-tier health system.

METHODS

A population-based cohort study of adults implanted with a PPM between 1995 and 2009 in Western Australia. The association of funding outcomes derived from linked administrative data was tested in multivariate logistic regression models.

RESULTS

There were 9748 PPMs implanted, 48% being among privately funded patients. The mean age was 75 years for both public and private patients. Private patients had better health status (fewer with cardiac conditions and lower non-cardiac comorbidity scores), were less likely to be an emergency admission (33% vs 60%, P < 0.001) and more likely to have dual- or triple-chamber pacing. Mean length of stay was significantly greater for private patients (4.3 (standard deviation 6.3) vs 5.1 (6.8) days <0.001), related to longer elective admissions. Crude mortality was lower for private patients in-hospital (0.7 vs 1.3%), 30-day post-procedure (1.3 vs 2.1%) and at 1 year (7.3 vs 9.5%). Emergency admission, comorbidity and other demographic and clinical factors, not funding source, were significant predictors of these outcomes.

CONCLUSIONS

There was no difference between publicly and privately funded patients in study outcomes, after adjustment for demographic and clinical factors. The exception was longer hospital stay for elective PPM among privately funded patients.

Australian Cardiovascular Health and Rehabilitation Association (ACRA) core components of cardiovascular disease secondary prevention and cardiac rehabilitation 2014

BACKGROUND

Research on Australian cardiovascular disease secondary prevention and cardiac rehabilitation to guide practice needs updating to reflect current context of practice. It is timely therefore to review the core components that underpin effective services that deliver maximum benefits for participants.

METHODS

The Australian Cardiovascular Health and Rehabilitation Association (ACRA) convened an inter-agency, multidisciplinary, nationally representative expert panel of Australia's leading cardiac rehabilitation clinicians, researchers and health advocates who reviewed the research evidence.

RESULTS

Five core components for quality delivery and outcomes of services were identified and are recommended: 1) Equity and access to services, 2) Assessment and short-term monitoring, 3) Recovery and longer term maintenance, 4) Lifestyle/behavioural modification and medication adherence, and 5) Evaluation and quality improvement.

CONCLUSIONS

ACRA seeks to provide guidance on the latest evidence in cardiovascular disease secondary prevention and cardiac rehabilitation. Clinicians should use these core components to guide effective service delivery and promote high quality evidence based care. Directors of hospitals and health services should use these core components to aid decision-making about the development and maintenance of these services.

Sudden cardiac death rates in an Australian population: a data linkage study

Objective The aim of the present study was to develop criteria to identify sudden cardiac death (SCD) and estimate population rates of SCD using administrative mortality and hospital morbidity records in Western Australia. Methods Four criteria were developed using place, death within 24 h, principal and secondary diagnoses, underlying and associated cause of death, and/or occurrence of a post mortem to identify SCD. Average crude, age-standardised and age-specific rates of SCD were estimated using population person-linked administrative data. Results In all, 9567 probable SCDs were identified between 1997 and 2010, with one-third aged ≥35 years having no prior admission for cardiovascular disease. SCD was more frequent in men (62.1%). The estimated average annual crude SCD rate for the period was 34.6 per 100 000 person-years with an average annual age-standardised rate of 37.8 per 100 000 person-years. Age-specific standardised rates were 1.1 per 100 000 person-years and 70.7 per 100 000 person-years in people aged 1–34 and ≥35 years, respectively. Ischaemic heart disease (IHD) was recorded as the underlying cause of death in approximately 80% of patients aged ≥35 years, followed by valvular heart disease and heart failure. IHD was the most common cause of death in those aged 1–34 years, followed by unspecified cardiomyopathy and dysrhythmias. Conclusions Administrative morbidity and mortality data can be used to estimate rates of SCD and therefore provide a suitable methodology for monitoring SCD over time. The findings highlight the magnitude of SCD and its potential for public health prevention. What is known about the topic? There is considerable variability in rates of SCD worldwide. Different data sources and varied methods of case ascertainment likely contribute to this variation. What does this paper add? The rate of SCD in Australia is low compared with international estimates from USA, Ireland, Netherlands and China. Two in every three cases of SCD aged ≥35 years had a hospitalisation history of cardiovascular disease, highlighting the opportunity for prevention. What are the implications for practitioners? High-quality person-linked administrative hospital morbidity and registered mortality data can be used to estimate rates of SCD in the population. Understanding the magnitude and distribution of SCD is imperative for developing effective public health policy and prevention measures.

The transition from hospital to primary care for patients with acute coronary syndrome: insights from registry data

Despite guidelines advocating routine engagement with proven secondary prevention strategies, current uptake and access remain suboptimal. Australian registries of acute coronary syndrome have predominantly focused on inpatient care and have highlighted under-referral to cardiac rehabilitation, gaps in medication prescription and limited commencement of lifestyle change before discharge from hospital. Opportunities to improve equity, access and uptake of secondary prevention include better transition between acute and primary care, systematic delivery of prevention in primary care, workforce strengthening and embracing new technologies. Adopting a structured framework for delivery of secondary prevention in primary care will enhance continuity of care and improve coordination of services after acute coronary syndrome.

Disparities experienced by Aboriginal compared to non-Aboriginal metropolitan Western Australians in receiving coronary angiography following acute ischaemic heart disease: the impact of age and comorbidities

INTRODUCTION

Aboriginal Australians have a substantially higher frequency of ischaemic heart disease (IHD) events than their non-Aboriginal counterparts, together with a higher prevalence of comorbidities. The pattern of health service provision for IHD suggests inequitable delivery of important diagnostic procedures. Published data on disparities in IHD management among Aboriginal Australians are conflicting, and the role of comorbidities has not been adequately delineated. We compared the profiles of Aboriginal and non-Aboriginal patients in the metropolitan area undergoing emergency IHD admissions at Western Australian metropolitan hospitals, and investigated the determinants of receiving coronary angiography.

METHODS

Person-linked administrative hospital and mortality records were used to identify 28-day survivors of IHD emergency admission events (n =20,816) commencing at metropolitan hospitals in 2005-09. The outcome measure was receipt of angiography. The Aboriginal to non-Aboriginal risk ratio (RR) was estimated from a multivariable Poisson log-linear regression model with allowance for multiple IHD events in individuals. The subgroup of myocardial infarction (MI) events was modelled separately.

RESULTS

Compared with their non-Aboriginal counterparts, Aboriginal IHD patients were younger and more likely to have comorbidities. In the age- and sex-adjusted model, Aboriginal patients were less likely than others to receive angiography (RRIHD 0.77, 95% CI 0.72-0.83; RRMI 0.81, 95% CI 0.75-0.87) but in the full multivariable model this disparity was accounted for by comorbidities as well as IHD category and MI subtype, and private health insurance (RRIHD 0.95, 95% CI 0.89-1.01; RRMI 0.94, 95% CI 0.88-1.01). When stratified by age groups, this disparity was not significant in the 25-54 year age group (RRMI 0.95, 95% CI 0.88-1.02) but was significant in the 55-84 year age group (RRMI 0.88, 95% CI 0.77-0.99).

CONCLUSIONS

The disproportionate under-management of older Aboriginal IHD patients is of particular concern. Regardless of age, the disparity between Aboriginal and non-Aboriginal Australians in receiving angiography for acute IHD in a metropolitan setting is mediated substantially by comorbidities. This constellation of health problems is a 'double-whammy' for Aboriginal people, predisposing them to IHD and also adversely impacting on their receipt of angiography. Further research should investigate how older age and comorbidities influence clinical decision making in this context.

A systematic approach to chronic heart failure care: a consensus statement

The National Heart Foundation of Australia assembled an expert panel to provide guidance on policy and system changes to improve the quality of care for people with chronic heart failure (CHF). The recommendations have the potential to reduce emergency presentations, hospitalisations and premature death among patients with CHF. Best-practice management of CHF involves evidence-based, multidisciplinary, patient-centred care, which leads to better health outcomes. A CHF care model is required to achieve this. Although CHF management programs exist, ensuring access for everyone remains a challenge. This is particularly so for Aboriginal and Torres Strait Islander peoples, those from non-metropolitan areas and lower socioeconomic backgrounds, and culturally and linguistically diverse populations. Lack of data and inadequate identification of people with CHF prevents efficient patient monitoring, limiting information to improve or optimise care. This leads to ineffectiveness in measuring outcomes and evaluating the CHF care provided. Expanding current cardiac registries to include patients with CHF and developing mechanisms to promote data linkage across care transitions are essential. As the prevalence of CHF rises, the demand for multidisciplinary workforce support will increase. Workforce planning should provide access to services outside of large cities, one of the main challenges it is currently facing. To enhance community-based management of CHF, general practitioners should be empowered to lead care. Incentive arrangements should favour provision of care for Aboriginal and Torres Strait Islander peoples, those from lower socioeconomic backgrounds and rural areas, and culturally and linguistically diverse populations. Ongoing research is vital to improving systems of care for people with CHF. Future research activity needs to ensure the translation of valuable knowledge and high-quality evidence into practice.

Evaluation of long-term clinical and health service outcomes following coronary artery revascularisation in Western Australia (WACARP): a population-based cohort study protocol

INTRODUCTION

Coronary artery bypass grafting (CABG) and percutaneous coronary interventions (PCI) are procedures commonly performed on patients with significant obstructive coronary artery disease to relieve symptoms of ischaemia, improve survival or both. Although the efficacy of both procedures at the individual level has been established, the impact of advances in coronary artery revascularisation procedures (CARP) on long-term outcomes and cost-effectiveness at the population level are yet to be assessed. Our aim is to evaluate a minimum of 6-year outcomes and costs for the total population of patients who had CARP in Western Australia (WA) in 2000-2005.

METHODS AND ANALYSIS

This retrospective population cohort study will link clinical and administrative health data for a previously defined cohort including all patients in WA who had a CARP in the period 2000-2005. The cohort consists of 19,014 patients who had 21,175 procedures (15,429 PCI and 5746 CABG). We are now collecting a minimum of 6 years follow-up of morbidity and mortality data for the cohort using the WA Data Linkage System, clinical registries and hospital records, with 12 years follow-up for cases in the year 2000. Comparison of long-term outcomes for different CARP will be reported (PCI vs CABG; bare metal stents vs drug-eluting stents vs CABG). Cost-effectiveness analysis of CARP from the perspective of the healthcare sector will be performed using individual level cost data and average costs from Australian Refined Diagnosis Related Groups.

ETHICS AND DISSEMINATION

This study has received ethics approval from the University of Western Australia, the Western Australian Department of Health and all participating hospitals. Being a large population cohort study, approval included a waiver of informed consent. All findings will be presented at local, national and international healthcare/academic conferences and published in peer-reviewed journals.

Outcomes after first percutaneous coronary intervention for acute myocardial infarction according to patient funding source

Background

Disparities in the use of invasive coronary artery revascularisation procedures to manage acute myocardial infarction (AMI) have been found in several developed economies. Factors such as socio-economic status, income and funding source may influence the use of invasive procedures and have also been associated with ongoing care. The objectives of this study were to determine whether outcomes for patients at one and five years after AMI treated with first-ever percutaneous coronary intervention (PCI) were the same for public and privately funded patients.

Methods

Retrospective, population-based cohort study using linked data to identify 30-day survivors of AMI treated with PCI in the index admission between 1995 and 2008 in Western Australian hospitals. The main outcome measures were admission for another PCI, re-AMI, and all-cause and cardiac mortality at one and five years.

Results

At one year, private patients were at greater adjusted risk for another PCI (HR 1.62 [1.36 – 1.94]; p < 0.001) than public patients, and more likely to have an additional revascularisation procedure from 90 days to 5 years (HR 1.33 [1.11 – 1.58]; p < 0.001). They were at less risk for all-cause death within five years (HR 0.69 [0.62–0.91]; p = 0.01) with a trend to reduced risk for cardiac death and re-AMI.

Conclusions

Treatment as a private patient for AMI with first PCI is associated with an increased likelihood of additional coronary revascularisation procedure within 12 months and to five years, and a reduced risk for all-cause mortality to 5 years. While additional procedures were not associated with poorer outcomes, there was no clear relationship between better outcomes and additional procedures. Other lifestyle and health care factors may contribute to the significant reduction in all-cause mortality and the trends to reduced hazard for AMI and cardiac death among private patients.

Comparative trends in the incidence of hospitalized myocardial infarction and coronary heart disease in adults with and without diabetes mellitus in Western Australia from 1998 to 2010

BACKGROUND

The risk of myocardial infarction (MI) is elevated in people with diabetes mellitus (DM) compared with non-DM counterparts. The aim of this study was to compare population trends in the incidence of hospitalized MI and coronary heart disease (CHD) in adults with and without DM.

METHODS AND RESULTS

All incident hospitalized MI and CHD events were identified from whole-population hospital data in Western Australia for 1998 to 2010. Annual age-standardized MI and CHD incidence rates were calculated for people with and without DM aged 35 to 84 years and age-adjusted trends estimated from Poisson regression. There were 26 610 incident MI and 56 142 incident CHD cases during the study period. MI incidence rates fell in men (-2.9%/y; 95% confidence interval [CI], -3.7 to -2.1) and women (-3.8%/y; 95% CI, -4.8 to -2.1) with DM, representing overall reductions of 35% and 43% respectively, with comparable reductions in incident CHD. Downward trends in MI incidence in those with DM were most apparent in 55- to 84-year olds. In adults without DM, there was no decline in MI incidence but a small significant decrease in incident CHD (men, -1.5%/y; 95% CI, -1.8 to -1.2 and women, -1.3%/y; 95% CI, -1.8 to -0.9). Incidence rate ratios for MI in men with versus without DM declined from 4.5 (95% CI, 4.2-4.8) to 3.1 (95% CI, 2.9-3.3) and from 6.0 (95% CI, 5.4-6.6) to 3.8 (95% CI, 3.5-4.1) in women between 1998 and 2010.

CONCLUSIONS

There have been significant reductions in incidence rates of MI and CHD in adults with DM between 1998 and 2010; however, the excess risk of MI incidence remains 3 to 4× greater in people with DM.

One third of hospital costs for atherothrombotic disease are attributable to readmissions: a linked data analysis

Background

Cardiovascular disease is the most frequent cause of death in Australia, with an associated cost burden of 11% of Australian annual health expenditure of which 40% is for hospital admissions. We investigated health outcomes and the components of hospital expenditure in the two years after an atherothrombotic disease admission to a tertiary hospital in an Australian setting.

Methods

Using data linkage we analysed two years of hospitalisation data and death records of all men and women aged 35–84 years with an admission to a Western Australian tertiary hospital for atherothrombotic disease in 2007. Costs were identified by matching the Australian refined diagnostic related group on the admission records to the published schedules of public and private hospital costs for the period of interest, and converted to 2013 Australian dollars.

Results

Of 6172 patients studied (74% coronary, 20% cerebrovascular, 6% peripheral), 783 (13%) died during follow-up and 174 of these were in hospital case-fatalities at index. Thirty-two percent of patients (n = 1965) accounted for 3172 readmissions to hospital with one in three having multiple hospitalisations. The hazard ratio of atherothrombotic disease readmission was 1.45 (95% CI 1.27, 1.66) in those with more than one vascular territory affected compared to those with only one territory affected after controlling for age, sex, comorbidity, admission type, procedures, and episode length of stay. The total index plus 2-year admission cost for atherothrombotic disease was calculated at $101 million; $71 million for index, and $30 million for readmissions.

Conclusions

Among patients hospitalised with atherothrombotic disease, the cost of related rehospitalisations within 24 months is almost a third of the total. Much of the readmission costs fell within the first year. Whether readmissions and cost associated with atherothrombotic disease can be lowered through secondary prevention measures requires further investigation.

Transfers to metropolitan hospitals and coronary angiography for rural Aboriginal and non-Aboriginal patients with acute ischaemic heart disease in Western Australia

Background

Aboriginal people have a disproportionately higher incidence rate of ischaemic heart disease (IHD) than non-Aboriginal people. The findings on Aboriginal disparity in receiving coronary artery procedures are inconclusive. We describe the profile and transfers of IHD patients admitted to rural hospitals as emergency admissions and investigate determinants of transfers and coronary angiography.

Methods

Person-linked hospital and mortality records were used to identify 28-day survivors of IHD events commencing at rural hospitals in Western Australia. Outcome measures were receipt of coronary angiography, transfer to a metropolitan hospital, and coronary angiography if transferred to a metropolitan hospital.

Results

Compared to non-Aboriginal patients, Aboriginal patients with IHD were more likely to be younger, have more co-morbidities, reside remotely, but less likely to have private insurance. After adjusting for demographic characteristics, Aboriginal people with MI were less likely to be transferred to a metropolitan hospital, and if transferred were less likely to receive coronary angiography. These disparities were not significant after adjusting for comorbidities and private insurance. In the full multivariate model age, comorbidities and private insurance were adversely associated with transfer to a metropolitan hospital and coronary angiography.

Conclusion

Disparity in receiving coronary angiography following emergency admission for IHD to rural hospitals is mediated through the lower likelihood of being transferred to metropolitan hospitals where this procedure is performed. The likelihood of a transfer is increased if the patient has private insurance, however, rural Aboriginal people have a lower rate of private insurance than their non-Aboriginal counterparts. Health practitioners and policy makers can continue to claim that they treat Aboriginal and non-Aboriginal people alike based upon clinical indications, as private insurance is acting as a filter to reduce rural residents accessing interventional cardiology. If health practitioners and policy makers are truly committed to reducing health disparities, they must reflect upon the broader systems in which disparity is perpetuated and work towards a systems improvement.

Disparities in equity and access for hospitalised atherothrombotic disease

OBJECTIVE

This study of equity and access characterises admissions for coronary, cerebrovascular and peripheral arterial disease by hospital type (rural, tertiary and non-tertiary metropolitan) in a representative Australian population.

METHODS

We conducted a descriptive analysis using data linkage of all residents aged 35-84 years hospitalised in Western Australia with a primary diagnosis for an atherothrombotic event in 2007. We compared sociodemographic and clinical features by atherothrombotic territory and hospital type.

RESULTS

There were 11670 index admissions for atherothrombotic disease in 2007 of which 46% were in tertiary hospitals, 41% were in non-tertiary metropolitan hospitals and 13% were in rural hospitals. Coronary heart disease comprised 72% of admissions, followed by cerebrovascular disease (19%) and peripheral arterial disease (9%). Comparisons of socioeconomic disadvantage reveal that for those admitted to rural hospitals, more than one-third were in the most disadvantaged quintile, compared with one-fifth to any metropolitan hospital.

CONCLUSIONS

Significant differences in demographic characteristics were evident between Western Australian tertiary and non-tertiary hospitals for patients hospitalised for atherothrombotic disease. Notably, the differences among tertiary, non-tertiary metropolitan and rural hospitals were related to socioeconomic disadvantage. This has implications for atherothrombotic healthcare provision and the generalisation of research findings from studies conducted exclusively in the tertiary metropolitan hospitals.

Cross vascular risk for first and recurrent hospitalised atherothrombosis determined retrospectively from linked data

OBJECTIVES

To determine the sex-specific and age-specific risk ratios for the first-ever and recurrent hospitalisation for cerebrovascular, coronary and peripheral arterial disease in persons with other vascular history versus without other vascular history in Western Australia from 2005to 2007.

DESIGN

Cross-sectional linkage study.

SETTING

Hospitalised population in a representative Australian State.

PARTICIPANTS

All persons aged 34-85 years between 1 January 2005 and 31 December 2007 were hospitalised with a principal diagnosis of atherothrombosis.

DATA SOURCES

Person-linked file of statutory-collected administrative morbidity and mortality records.

MAIN OUTCOME MEASURES

Sex-specific and age-specific risk ratios for the first-ever and recurrent hospitalisations for symptomatic atherothrombosis of the brain, coronary and periphery using a 15-year look-back period lead to the determining of prior events.

RESULTS

Over 3 years, 40 877 (66% men; 55% first-ever) were hospitalised for atherothrombosis. For each arterial territory, age-specific recurrent rates were higher than the corresponding first-ever rates, with the biggest difference seen in the youngest age groups. For all types of first-ever atherothrombosis, the rates were higher in those with other vascular history and the risk ratios declined with an advancing age (trend: all p<0.0001) and remained significantly >1 even for 75-84 years old. However, for recurrent events, the rates were marginally higher in those with other vascular history and no risk ratio age trend was apparent with several not significantly >1 (trend: all p>0.13).

CONCLUSIONS

This study of hospitalised atherothrombosis suggests first-events predominate and that the risk of further events in the same or other arterial territory is very high for all ages and both sexes, accentuating the necessity for an early and sustained active prevention.

Complex impact of remoteness on the incidence of myocardial infarction in Aboriginal and non-Aboriginal people in Western Australia

OBJECTIVE

To determine the impact of remoteness on Aboriginal and non-Aboriginal myocardial infarction incidence rates in men and women of different ages.

DESIGN

Descriptive study.

SETTING

Western Australia.

PARTICIPANTS

Incident cases of myocardial infarction in Western Australia from 2000-2004 identified from person-linked files of hospital and mortality records. Analysis was undertaken for Aboriginal and non-Aboriginal populations, separately and combined, by broad age group, sex and remoteness.

MAIN OUTCOME MEASURE

Incidence of myocardial infarction.

RESULTS

In the combined analysis, age-standardised incidence was significantly higher for men in very remote areas (rate ratio 1.31: 95% confidence interval (CI), 1.19-1.45) and in women in both regional (rate ratio 1.12: 95% CI, 1.01-1.20) and very remote (rate ratio 2.05: 95% CI, 1.75-2.41) areas. Aboriginal rates were substantially higher than non-Aboriginal rates in all substrata. Compared with metropolitan people, regional Aboriginal men and very remote non-Aboriginal men aged 25-54 years had significantly higher incidence rates. For the remaining rural strata, there was either no geographical disadvantage or inconclusive findings.

CONCLUSIONS

Non-metropolitan disadvantage in myocardial infarction rates is confirmed in regional areas and women in very remote areas. This disadvantage is partly explained by the high rates in Aboriginal people. Non-metropolitan dwellers are not uniformly disadvantaged, reflecting the interplay of the many factors contributing to the complex relationship between myocardial infarction incidence and sex, age, Aboriginality and residence. Aboriginal Western Australians in all regions and young non-Aboriginal men living in very remote areas need to be targeted to reduce disparities in myocardial infarction.

Concordance between administrative health data and medical records for diabetes status in coronary heart disease patients: a retrospective linked data study

BACKGROUND

Administrative data are a valuable source of estimates of diabetes prevalence for groups such as coronary heart disease (CHD) patients. The primary aim of this study was to measure concordance between medical records and linked administrative health data for recording diabetes in CHD patients, and to assess temporal differences in concordance. Secondary aims were to determine the optimal lookback period for identifying diabetes in this patient group, whether concordance differed for Indigenous people, and to identify predictors of false positives and negatives in administrative data.

METHODS

A population representative sample of 3943 CHD patients hospitalized in Western Australia in 1998 and 2002-04 were selected, and designated according to the International Classification of Diseases (ICD) version in use at the time (ICD-9 and ICD-10 respectively). Crude prevalence and concordance were compared for the two samples. Concordance measures were estimated from administrative data comparing diabetes status recorded on the selected CHD admission ('index admission') and on any hospitalization in the previous 1, 2, 5, 10 or 15 years, against hospital medical records. Potential modifiers of agreement were determined using chi-square tests and multivariable logistic regression models.

RESULTS

Identification of diabetes on the index CHD admission was underestimated more in the ICD-10 than ICD-9 sample (sensitivity 81.5% versus 91.1%, underestimation 15.1% versus 4.4% respectively). Sensitivity increased to 89.6% in the ICD-10 period using at least 10 years of hospitalization history. Sensitivity was higher and specificity lower in Indigenous patients, and followed a similar pattern of improving concordance with increasing lookback period. Characteristics associated with false negatives for diabetes on the index CHD hospital admission were elective admission, in-hospital death, principal diagnosis, and in the ICD-10 period only, fewer recorded comorbidities.

CONCLUSIONS

The accuracy of identifying diabetes status in CHD patients is improved in linked administrative health data by using at least 10 years of hospitalization history. Use of this method would reduce bias when measuring temporal trends in diabetes prevalence in this patient group. Concordance measures are as reliable in Indigenous as non-Indigenous patients.

Age- and sex-specific trends in the incidence of hospitalized acute coronary syndromes in Western Australia

BACKGROUND- The incidence of myocardial infarction has declined during the past 4 decades in many populations. However, there are limited population data measuring trends in acute coronary syndromes (ACS). We therefore examined temporal trends in the incidence of hospitalized ACS by age and sex in a population-based cohort. METHODS AND RESULTS- The Western Australian Data Linkage System, a repository of linked administrative health data, was used to identify 29 421 incident ACS hospitalizations between 1996 and 2007. Poisson log-linear regression models were used to calculate incidence rate changes. Age-standardized incidence rates of ACS declined annually in men by 1.7% (95% confidence interval [CI], -2.1 to -1.3) and in women by 1.6% (95% CI, -2.1 to -1.0). These declining rates were underpinned by annual reductions in the incidence of unstable angina (men, -3.0%; 95% CI, -3.7 to -2.4; women, -2.5; 95% CI, -3.3 to -1.7), whereas annual changes in myocardial infarction incidence were less (men, -1.0%; 95% CI, -1.5 to -0.5; women, -0.8%; 95% CI, -1.6 to 0). However, the overall trends masked age group differences, with ACS incidence increasing annually in 35- to 54-year-old women (2.3%; 95% CI, 1.0 to 3.8), predominantly driven by increasing incidence of myocardial infarction. CONCLUSIONS- The age-standardized incidence of ACS decreased significantly in Western Australia from 1996 to 2007. However, an increase in ACS incidence in women ages 35 to 54 years is troubling and warrants further investigation.

Aboriginal to non-Aboriginal differentials in 2-year outcomes following non-fatal first-ever acute MI persist after adjustment for comorbidity

BACKGROUND

We investigated the relationship between Aboriginality and 2-year cardiovascular disease outcomes in non-fatal first-ever myocardial infarction during 2000-04, with progressive adjustment of covariates, including comorbidities.

DESIGN

Historical cohort study.

METHODS

Person-linked hospital and mortality records were used to identify 28-day survivors of first-ever myocardial infarction in Western Australia during 2000-04 with 15-year lookback. The outcome measures were: (1) cardiovascular disease death; (2) recurrent admission for myocardial infarction; and (3) the composite of (1) and (2).

RESULTS

Compared with non-Aboriginal patients, Aboriginals were younger and more likely to live remotely. The proportions having 5-year histories of diabetes and chronic kidney disease were double and triple those of non-Aboriginals. When adjusting for demographic variables alone, the Aboriginal to non-Aboriginal hazard ratios for cardiovascular death or recurrent myocardial infarction were 3.6 (95% CI 2.5-5.3) in men and 4.5 (95% CI 2.8-7.3) in women. After adjustment for comorbidities, including diabetes, chronic kidney disease and heart failure, the hazard ratios decreased 36% and 47% to 2.3 (1.6-3.0) and 2.4 (1.5-4.0) in males and females, respectively.

CONCLUSIONS

The high prevalence of comorbidities in Aboriginal people, including diabetes, kidney disease, heart failure, and other risk factors contribute substantially to the disparity in post-myocardial infarction outcomes in Aboriginal people, reinforcing the importance of both primary prevention and comprehensive management of chronic conditions in this population. Aboriginality remains a significant independent risk factor for disease recurrence or mortality, even after adjusting for comorbidity, suggesting the need for society-level interventions addressing social disadvantage.

Under-ascertainment of Aboriginality in records of cardiovascular disease in hospital morbidity and mortality data in Western Australia: a record linkage study

BACKGROUND

Measuring the real burden of cardiovascular disease in Australian Aboriginals is complicated by under-identification of Aboriginality in administrative health data collections. Accurate data is essential to measure Australia's progress in its efforts to intervene to improve health outcomes of Australian Aboriginals. We estimated the under-ascertainment of Aboriginal status in linked morbidity and mortality databases in patients hospitalised with cardiovascular disease.

METHODS

Persons with public hospital admissions for cardiovascular disease in Western Australia during 2000-2005 (and their 20-year admission history) or who subsequently died were identified from linkage data. The Aboriginal status flag in all records for a given individual was variously used to determine their ethnicity (index positive, and in all records both majority positive or ever positive) and stratified by region, age and gender. The index admission was the baseline comparator.

RESULTS

Index cases comprised 62,692 individuals who shared a total of 778,714 hospital admissions over 20 years, of which 19,809 subsequently died. There were 3,060 (4.9%) persons identified as Aboriginal on index admission. An additional 83 (2.7%) Aboriginal cases were identified through death records, increasing to 3.7% when cases with a positive Aboriginal identifier in the majority (≥50%) of previous hospital admissions over twenty years were added and by 20.8% when those with a positive flag in any record over 20 years were incorporated. These results equated to underestimating Aboriginal status in unlinked index admission by 2.6%, 3.5% and 17.2%, respectively. Deaths classified as Aboriginal in official records would underestimate total Aboriginal deaths by 26.8% (95% Confidence Interval 24.1 to 29.6%).

CONCLUSIONS

Combining Aboriginal determinations in morbidity and official death records increases ascertainment of unlinked cardiovascular morbidity in Western Australian Aboriginals. Under-identification of Aboriginal status is high in death records.