Can we monitor heart attack in the troponin era? Evidence from a population-based cohort study.

BACKGROUND: Troponins (highly sensitive biomarkers of myocardial damage) increase counts of myocardial infarction (MI) in clinical practice, but their impact on trends in admission rates for MI in National statistics is uncertain. METHODS: Cases coded as MI or other cardiac diagnoses in the Hospital Morbidity Data Collection (MI-HMDC) in Western Australia in 1998 and 2003 were classified using revised criteria for MI developed by an International panel convened by the American Heart Association (AHA criteria) using information on symptoms, ECGs and cardiac biomarkers abstracted from samples of medical notes. Age-sex standardized rates of MI-HMDC were compared with rates of MI based on AHA criteria including troponins (MI-AHA) or traditional biomarkers only (MI-AHAck). RESULTS: Between 1998 and 2003, rates of MI-HMDC decreased by 3.5% whereas rates of MI-AHA increased by 17%, a difference largely due to increased false-negative cases in the HMDC associated with marked increased use of troponin tests in cardiac admissions generally, and progressively lower test thresholds. In contrast, rates of MI-AHAck declined by 18%. CONCLUSIONS: Increasing misclassification of MI-AHA by the HMDC may be due to reluctance by clinicians to diagnose MI based on relatively small increases in troponin levels. These influences are likely to continue. Monitoring MI using AHA criteria will require calibration of commercially available troponin tests and agreement on lower diagnostic thresholds for epidemiological studies. Declining rates of MI-AHA ck are consistent with long-standing trends in MI in Western Australia, suggesting that neither MI-HMDC nor MI-AHA reflect the true underlying population trends in MI.

Using clinical trial data and linked administrative health data to reduce the risk of adverse events associated with the uptake of newly released drugs by older Australians: a model process.

BACKGROUND: The study was undertaken to evaluate the contribution of a process which uses clinical trial data plus linked de-identified administrative health data to forecast potential risk of adverse events associated with the use of newly released drugs by older Australian patients. METHODS: The study uses publicly available data from the clinical trials of a newly released drug to ascertain which patient age groups, gender, comorbidities and co-medications were excluded in the trials. It then uses linked de-identified hospital morbidity and medications dispensing data to investigate the comorbidities and co-medications of patients who suffer from the target morbidity of the new drug and who are the likely target population for the drug. The clinical trial information and the linked morbidity and medication data are compared to assess which patient groups could potentially be at risk of an adverse event associated with use of the new drug. RESULTS: Applying the model in a retrospective real-world scenario identified that the majority of the sample group of Australian patients aged 65 years and over with the target morbidity of the newly released COX-2-selective NSAID rofecoxib also suffered from a major morbidity excluded in the trials of that drug, indicating a substantial potential risk of adverse events amongst those patients. This risk was borne out in post-release morbidity and mortality associated with use of that drug. CONCLUSIONS: Clinical trial data and linked administrative health data can together support a prospective assessment of patient groups who could be at risk of an adverse event if they are prescribed a newly released drug in the context of their age, gender, comorbidities and/or co-medications. Communication of this independent risk information to prescribers has the potential to reduce adverse events in the period after the release of the new drug, which is when the risk is greatest.Note: The terms 'adverse drug reaction' and 'adverse drug event' have come to be used interchangeably in the current literature. For consistency, the authors have chosen to use the wider term 'adverse drug event' (ADE).

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.

Discordant age and sex-specific trends in the incidence of a first coronary heart disease event in Western Australia from 1996 to 2007.

OBJECTIVE: To determine age- and sex-specific population trends in fatal and non-fatal first coronary heart disease (CHD) events in Western Australia from 1996 to 2007. DESIGN: Longitudinal retrospective population study. SETTING: State-wide population. PATIENTS: All residents aged 35-84 years during 1996-2007 who died or were hospitalised with a principal diagnosis of acute CHD. DATA SOURCES: Person-linked file of mortality and morbidity records. MAIN OUTCOME MEASURES: Age-standardised (35-84 years) and age-specific (35-54, 55-69, 70-84 years) rates by gender for a first CHD event were calculated with a 10-year lead-in period to define first events. RESULTS: From 1996 to 2007 there were 36 631 first CHD events, including 8518 (23%) fatal cases in those aged 35-84 years. Overall, age-adjusted rates for fatal first CHD declined 5.3%/year in men (95% CI -6.1% to -4.6%) and 6.5%/year in women (95% CI -7.5% to -5.5%). However, age-specific fatal first CHD rates were neutral in both men aged 35-54 years (0.1%/year; 95% CI -1.8% to 2.1%) and women of the same age, (-1.6%/year; 95% CI -5.6% to 2.5%). Age-specific trends in non-fatal CHD rates reflected the same trends in fatal CHD events in men and women, with rates reportedly increasing in women aged 35-54 years (2.5%/year (95% CI 1.1% to 3.9%). CONCLUSION: The age-specific decline in fatal and non-fatal first CHD rates in older men and women was not observed in those aged 35-54 years. These novel findings provide evidence for a levelling in the CHD incidence rates in younger adults and puts renewed importance on primary prevention in this group.

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.

Population trends of recurrent coronary heart disease event rates remain high.

BACKGROUND: Survivors of nonfatal coronary heart disease (CHD) can reduce their risk of further events by various preventive interventions. The impact of such measures as delivered over 11 years, on population rates of subsequent major CHD events, has not been extensively studied. This study determined population trends in the prevalence of clinically manifest CHD and the proportion of major CHD events that occur in this population. METHODS AND RESULTS: A population longitudinal person-based event-linked file of CHD extracted from State Hospital Morbidity Data and Death Registry for 1980 to 2005 was used to identify, for each year from 1995 to 2005, survivors who had a hospitalization for CHD over the previous 15 years (population with established CHD), and to examine the occurrence of CHD death and hospitalization with a principal diagnosis of myocardial infarction in both populations with and without established CHD. The average annual age-standardized prevalence of CHD in the Perth metropolitan region (population 1.6 million) was 28 373 (8.8%) in men and 14 966 (4.0%) in women. Age-specific prevalence increased exponentially with age, from <1% in 35 to 39 age group to 42% in 80 to 84 age group in men and half that in women. The percentage of total CHD events (n=28 941) that occurred in the population with established CHD was approximately 43% in both men and women, 55% and 51%, respectively, for CHD death and 35% and 36% for nonfatal myocardial infarction. CONCLUSIONS: More than 40% of major CHD events annually occur in persons with manifest disease, highlighting the imperative to implement systems of care that support effective secondary prevention.