Exploring the effects of transfers and readmissions on trends in population counts of hospital admissions for coronary heart disease: a Western Australian data linkage study.

OBJECTIVES: To develop a method for categorising coronary heart disease (CHD) subtype in linked data accounting for different CHD diagnoses across records, and to compare hospital admission numbers and ratios of unlinked versus linked data for each CHD subtype over time, and across age groups and sex. DESIGN: Cohort study. DATA SOURCE: Person-linked hospital administrative data covering all admissions for CHD in Western Australia from 1988 to 2013. MAIN OUTCOME: Ratios of (1) unlinked admission counts to contiguous admission (CA) counts (accounting for transfers), and (2) 28-day episode counts (accounting for transfers and readmissions) to CA counts stratified by CHD subtype, sex and age group. RESULTS: In all CHD subtypes, the ratios changed in a linear or quadratic fashion over time and the coefficients of the trend term differed across CHD subtypes. Furthermore, for many CHD subtypes the ratios also differed by age group and sex. For example, in women aged 35-54 years, the ratio of unlinked to CA counts for non-ST elevation myocardial infarction admissions in 2000 was 1.10, and this increased in a linear fashion to 1.30 in 2013, representing an annual increase of 0.0148. CONCLUSION: The use of unlinked counts in epidemiological estimates of CHD hospitalisations overestimates CHD counts. The CA and 28-day episode counts are more aligned with epidemiological studies of CHD. The degree of overestimation of counts using only unlinked counts varies in a complex manner with CHD subtype, time, sex and age group, and it is not possible to apply a simple correction factor to counts obtained from unlinked data.

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.

Acute myocardial infarction hospitalization and treatment: Areas with a high percentage of First Nations identity residents.

BACKGROUND: Deaths from acute myocardial infarction (AMI) are higher among First Nations people than among non-Aboriginal Canadians. Hospital interventions often involve revascularization: percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). Because patients' ethnicity is not reported consistently in hospital records, no national information is available about AMI hospitalizations or the use of such procedures among First Nations people. DATA AND METHODS: This study uses an area-based approach to identify AMI hospital patients who live in Dissemination Areas with relatively high percentages of First Nations residents. Within the AMI patient cohort, procedures received during the hospital admission were identified. RESULTS: The age-standardized hospitalized AMI event rates were 276.8 per 100,000 population for residents of high-percentage First Nations identity areas and 157.1 per 100,000 population for residents of low-percentage Aboriginal identity areas. AMI patients from high-percentage First Nations identity areas were less likely than patients from low-percentage Aboriginal identity areas to undergo revascularization, a difference largely driven by a lower PCI procedure rate. The lower PCI procedure rate persisted when controlling for age, sex, rural/urban residence, and the patient's condition at admission. INTERPRETATION: Residents of high-percentage First Nations identity areas were more likely to be hospitalized for AMI, but were less likely to undergo revascularization.