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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. [ABSTRACT FROM AUTHOR]

Background: Intraoperative complications, particularly bile duct injuries (BDIs), have increased since the introduction of laparoscopic cholecystectomy (LC). This excess risk is expected to decline as surgeon experience in laparoscopic surgery increases. Methods: This was a population-based study of trends in intraoperative injuries in 33309 cholecystectomies carried out in Western Australia between 1988 and 1998, based on hospital discharge abstracts. Endpoints were identified from diagnostic and procedure codes in index or postoperative readmissions, or a register of endoscopic retrograde cholangiopancreatography procedures, and validated using hospital records. Multivariate analysis was used to estimate the risk of complications associated with potential risk factors. Results: Following the introduction of LC in 1991, the prevalence of all complications doubled by 1994 then stabilized, whereas that of BDI declined after 1994. The risk of complications increased with age, was higher in men, teaching and country hospitals, and was higher for LC and more complicated operations. It was lower when intraoperative cholangiography was performed and with increasing surgeon experience. Approximately 20 per cent of all complications and 30 per cent of BDIs were attributable to surgeons who had performed 200 or fewer cholecystectomies in the previous 5 years. Conclusion: The risk of intraoperative complications declined with increasing surgical experience and use of intraoperative cholangiography. [ABSTRACT FROM AUTHOR]

The Wittenoom crocidolite (blue asbestos) mine and mill ceased operating in 1966. The impact of this industry on asbestos-related disease in Western Australia has been immense. Use of the employment records of the Australian Blue Asbestos Company and records of the Wittenoom township residents has permitted two cohorts of people with virtually exclusive exposure to crocidolite to be assembled and studied. Follow-up of these two cohorts has been conducted through data linkage with available hospital, mortality and cancer records. The evolution of asbestos-related disease has been recorded and, with the establishment of exposure measurements, quantitative exposure-response relationships have been estimated. There has been an ongoing epidemic of mortality from lung cancer and malignant mesothelioma and, less so, from asbestosis. Wittenoom crocidolite was used extensively in asbestos-cement products in Western Australia. As a result, the state has recorded a higher malignant-mesothelioma mortality rate than in any other Australian state and in any defined general population in the world. Thus, the legacy of Wittenoom has extended beyond the mine and the town, and is still evident more than 50 years after the closure of the mine., (© The Author(s) 2019; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.)

Background: Population-based coronary heart disease (CHD) studies have focused on myocardial infarction (MI) with limited data on trends across the spectrum of CHD. We investigated trends in hospitalisation rates for acute and chronic CHD subgroups in England and Australia from 1996 to 2013., Methods: CHD hospitalisations for individuals aged 35-84 years were identified from electronic hospital data from 1996 to 2013 for England and Australia and from the Oxford Region and Western Australia. CHD subgroups identified were acute coronary syndromes (ACS) (MI and unstable angina) and chronic CHD (stable angina and 'other CHD'). We calculated age-standardised and age-specific rates and estimated annual changes (95% CI) from age-adjusted Poisson regression., Results: From 1996 to 2013, there were 4.9 million CHD hospitalisations in England and 2.6 million in Australia (67% men). From 1996 to 2003, there was between-country variation in the direction of trends in ACS and chronic CHD hospitalisation rates (p<0.001). During 2004-2013, reductions in ACS hospitalisation rates were greater than for chronic CHD hospitalisation rates in both countries, with the largest subgroup declines in unstable angina (England: men: -7.1 %/year, 95% CI -7.2 to -7.0; women: -7.5 %/year, 95% CI -7.7 to -7.3; Australia: men: -8.5 %/year, 95% CI -8.6 to -8.4; women: -8.6 %/year, 95% CI -8.8 to -8.4). Other CHD rates increased in individuals aged 75-84 years in both countries. Chronic CHD comprised half of all CHD admissions, with the majority involving angiography or percutaneous coronary intervention., Conclusions: Since 2004, rates of all CHD subgroups have fallen, with greater declines in acute than chronic presentations. The slower declines and high proportion of chronic CHD admissions undergoing coronary procedures requires greater focus., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

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., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objectives: We examined differentials in short-term (30-day mortality) and 1-year mortality (in 30-day survivors) following index (first-ever) hospitalisation for heart failure (HF), between rural and metropolitan patients resident in Western Australia., Design: A population-based cohort study., Setting: Hospitalised patients in Western Australia, Australia., Participants: Index patients aged 20-84 years with a first-ever hospitalisation for HF between 2000 and 2009 (with no prior admissions for HF in previous 10 years), identified using the Western Australia linked health data., Main Outcome Measures: 30-day and 1-year all-cause mortality (in 30-day survivors) following index admission for HF., Results: Of 17 379 index patients with HF identified, 25.9% (4499) were from rural areas. Rural patients were significantly younger at first HF hospitalisation than metropolitan patients. Aboriginal patients comprised 1.9% of metropolitan and 17.2% of rural patients. Despite some statistical differences, the prevalence of antecedents including ischaemic heart disease, hypertension, diabetes and chronic kidney disease was high (>20%) in both subpopulations. After adjusting for age only, patients from rural areas had a higher risk of 30-day death (OR 1.16 (95% CI 1.01 to 1.33)) and 1-year death in 30-day survivors (HR 1.11 (95% CI 1.01 to 1.23)). These relative risk estimates increased and remained significant after further progressive adjustments for Aboriginality, socioeconomic status, insurance status, emergency presentation, individual comorbidities and revascularisation with OR 1.25 (1.06 to 1.48) for 30-day mortality and HR 1.13 (1.02 to 1.27) for 1-year mortality. The addition of the weighted Charlson index to the 30-day model improved the 'c' statistic (under the receiver operating characteristic curve) from 0.656 (using a variation of administrative claims model) to 0.714., Conclusions: Remoteness and variable access to healthcare can cause important disparities in health outcomes. Rural patients with HF in Western Australia have poorer risk-adjusted outcomes compared with metropolitan patients. This finding has important implications for chronic disease management and provision of health services in rural Australia.

Objectives: To compare the incidence of first heart failure (HF) hospitalisation, antecedent risk factors and 1-year mortality between Aboriginal and non-Aboriginal populations in Western Australia (2000-2009)., Methods: A population-based cohort aged 20-84 years comprising Aboriginal (n=1013; mean 54±14 years) and non-Aboriginal patients (n=16,366; mean 71±11 years) with first HF hospitalisation was evaluated. Age and sex-specific incidence rates and HF antecedents were compared between subpopulations. Regression models were used to examine 30-day and 1-year (in 30-day survivors) mortality., Results: Aboriginal patients were younger, more likely to reside in rural/remote areas (76% vs 23%) and to be women (50.6% vs 41.7%, all p<0.001). Aboriginal (versus non-Aboriginal) HF incidence rates were 11-fold higher in men and 23-fold in women aged 20-39 years, declining to about 2-fold in patients aged 70-84 years. Ischaemic and rheumatic heart diseases were more common antecedents of HF in younger (<55 years) Aboriginal versus non-Aboriginal patients (p<0.001). Hypertension, diabetes, chronic kidney disease, renal failure, chronic obstructive pulmonary disease, and a high Charlson comorbidity index (>=3) were also more prevalent in younger and older Aboriginal patients (p<0.001). Although 30-day mortality was similar in both subpopulations, Aboriginal patients aged<55 years had a 1.9 risk-adjusted hazard ratio (HR) for 1-year mortality (p=0.015)., Conclusions: Aboriginal people had substantially higher age and sex-specific HF incidence rate and prevalence of HF antecedents than their non-Aboriginal counterparts. HR for 1-year mortality was also significantly worse at younger ages, highlighting the urgent need for enhanced primary and secondary prevention of HF in this population., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Aims: To assess the level of evidence-based drug prescribing for acute coronary syndrome (ACS) at discharge from Western Australian (WA) hospitals and determine predictors of such prescribing in Aboriginal and non-Aboriginal patients., Methods: All Aboriginal (2002-2004) and a random sample of non-Aboriginal (2003) hospital admissions with a principal diagnosis of ACS were extracted from the WA Hospital Morbidity Data Collection of WA Data Linkage System. Clinical information, history of co-morbidities and drugs were collected from medical notes by trained data collectors. Evidence-based prescribing (EBP) was defined as prescribing of aspirin, statin and beta-blocker or angiotensin-converting enzyme inhibitor/angiotensin II antagonist., Results: Records for 1717 ACS patients discharged alive from hospitals were reviewed. The majority of patients (71%) had EBP, and there was no significant difference between Aboriginal and non-Aboriginal patients (70% vs 71%, P = 0.36). Conversely, a significantly higher proportion of Aboriginal patients had none of the drugs prescribed compared with non-Aboriginal patients (11% vs 7%, P < 0.01). EBP for ACS was independently associated with male sex (odds ratio (OR) 1.63, 95% confidence interval (CI) 1.26-2.11), previous admission for ACS (OR 1.83, 95% CI 1.39-2.42) and diabetes (OR 1.36, 95% CI 1.04-1.79). However, ACS patients living in regional and remote areas, attending district or private hospitals, or with a history of chronic obstructive pulmonary disease were significantly less likely to have ACS drugs prescribed at discharge., Conclusions: Opportunity exists to improve prescribing of recommended drugs for ACS patients at discharge from WA hospitals in both Aboriginal and non-Aboriginal patients. Attention regarding pharmaceutical management post-ACS is particularly required for patients from rural and remote areas, and those attending district and private hospitals., (© 2014 The Authors; Internal Medicine Journal © 2014 Royal Australasian College of Physicians.)

Background: Advances in treatment for acute myocardial infarction (AMI) are likely to have had a beneficial impact on the incidence of and deaths attributable to heart failure (HF) complicating AMI, although limited data are available to support this contention., Methods and Results: Western Australian linked administrative health data were used to identify 20 812 consecutive patients, aged 40 to 84 years, without prior HF hospitalized with an index (first) AMI between 1996 and 2007. We assessed the temporal incidence of and adjusted odds ratio/hazard ratio for death associated with HF concurrent with AMI admission and within 1 year after discharge. Concurrent HF comprised 75% of incident HF cases. Between the periods 1996-1998 and 2005-2007, the prevalence of HF after AMI declined from 28.1% to 16.5%, with an adjusted odds ratio of 0.50 (95% CI, 0.44 to 0.55). The crude 28-day case-fatality rate for patients with concurrent HF declined marginally from 20.5% to 15.9% (P < 0.05) compared with those without concurrent HF, in whom the case-fatality rate declined from 11.0% to 4.8% (P < 0.001). Concurrent HF was associated with a multivariate-adjusted odds ratio of 2.2 for 28-day mortality and a hazard ratio of 2.2 for 1-year mortality in 28-day survivors. Occurrence of HF within 90 days of the index AMI was associated with an adjusted hazard ratio of 2.7 for 1-year mortality in 90-day survivors., Conclusions: Despite encouraging declines in the incidence of HF complicating AMI, it remains a common problem with high mortality. Increased attention to these high-risk patients is needed given the lack of improvement in their long-term prognosis.

Background: The prevalence of hospitalised atherothrombotic disease affecting the coronary, cerebrovascular and peripheral vasculature is expected to increase due to improving survival, ageing and changing risk factor profiles. This study determined sex, age-standardised and age-specific (35-54, 55-69, 70-84years) prevalence of atherothrombotic disease and its association with diabetes and chronic kidney disease in Western Australian residents from 2000 to 2007., Methods: In a cross-sectional and longitudinal study, person-linked hospitalisations for atherothrombotic disease were obtained using records from 1985. From 2000 to 2007, total and vasculature-specific prevalence of atherothrombotic disease (as a principal diagnosis) was calculated using a 15-year lead-in to determine prior disease and comorbidity., Results: In 2007, 45,916 (8.6%) men and 22,782 (4.3%) women in Western Australia had established atherothrombotic disease and about 25% had diabetes, 10% had chronic kidney disease, and 5% had both. From 2000 to 2007 the estimated average annual change in age-standardised atherothrombotic disease prevalence was -0.6%/year (95% CI -0.8, -0.4) in men and -0.7%/year (95% CI -1.0, -0.4) in women. Similar modest declines were seen in age-standardised prevalence of monovascular and polyvascular atherothrombotic disease. The proportion of cases with diabetes increased by about 5%/year, the proportion having chronic kidney disease increased slowly in women (1.5%/year) and was stable in men, and the proportion with both comorbidities increased at about 9%/year., Conclusion: The age-standardised prevalence of atherothrombotic disease requiring hospitalisation has been in marginal decline in Western Australia this decade, despite the proportion of affected persons with diabetes and/or chronic kidney disease steadily rising., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objectives: To examine temporal trends in the incidence and recurrence of hospitalised coronary heart disease (CHD), cerebrovascular disease (CeVD) and peripheral arterial disease (PAD) separately and combined, and by the history of all forms of atherothrombotic disease (ATD)., Design: Population-based longitudinal data linkage study., Setting: Western Australia., Participants: All patients aged 35-84 years hospitalised in Western Australia for CHD, CeVD or PAD from 2000 to 2007., Main Outcome Measures: Age-standardised incidence and recurrence rates of CHD, CeVD and PAD stratified by ATD history, sex and age., Results: 107 576 events (65.9% men) were identified; 70% of all admissions were for CHD. In patients without a history of any ATD, incidence rates declined significantly in all groups, although the reduction in incident CHD in women was marginal (-0.7%/year, 95% CI -1.5 to +0.1%). The largest annual reductions in incidence rates were for PAD (men, -6.4%/year, 95% CI -7.7 to -5.0%; women, -5.4%/year, 95% CI -7.2 to -3.6%) and CeVD in women (-4.0%/year, 95% CI -5.0 to -3.0%). Falls in overall recurrence rates were greatest for CeVD (men, -3.2%/year, 95% CI -4.7 to -1.6%; women -4.6%/year, 95% CI -6.4 to -2.7%). Trends across all categories of polyvascular ATD were generally downward, although not all changes were statistically significant., Conclusion: The incidence and recurrence rates of hospitalised ATD have decreased over time, including in patients with disease involving multiple vascular territories. This implies that primary and secondary prevention strategies have been broadly effective. However, high absolute rates of recurrence and limited reduction in 35-54-year-old individuals highlight patient groups to target to reduce further the burden of ATD.

Background: It is uncertain if improvements in long-term cardiovascular (CV) mortality have occurred in both men and women with ischemic and non-ischemic forms of heart failure (HF)., Methods: The Western Australia Hospital Morbidity Database was used to identify all index (first-ever) hospitalizations for HF between 1990 and 2005. Patients were followed until death attributed to cardiovascular causes or censored on December 31, 2006 to determine 5-year survival. Cox proportional hazards models were used to compare the adjusted mortality hazard ratio (HR) during the study follow-up (4-year periods)., Results: A total of 21,507 patients (mean age 73.9 years, 49.1% women) were identified. Women were significantly older than men, and less likely to have ischemic HF (38.8% versus 46.1%). Over the period, age-standardized incidence of first HF hospitalization declined but with the least decline in women with non-ischemic HF (-13.3%) compared to other subgroups. Risk-adjusted 5-year CV mortality declined over the study period, with HR 0.64 (95% CI 0.60-0.68) for patients admitted in 1998-2001 compared to 1990-1993, with significant improvement in both forms of HF, and in both sexes and across age groups. However, overall total HF hospitalizations increased (+26.7%) over the period, particularly for non-ischemic HF (+43.7%), of which elderly women formed the predominant group., Conclusions: Risk-adjusted long-term survival improved similarly in men and women, including the elderly, with ischemic and non-ischemic forms of HF during 1990-2005 in Western Australia. However, there was a growing burden of HF hospitalizations particularly for HF of non-ischemic aetiology., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

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.

Background: We examined trends in incidence of first-ever (index) hospitalization for heart failure (HF), hospitalization rates, and 30-day and 1-year all-cause mortality subsequent to index hospitalization for HF., Methods and Results: The Western Australia Hospital Morbidity Database was used to identify a retrospective population-based cohort with an index hospitalization for HF in Western Australia between 1990 and 2005. Risk-adjusted temporal trends in mortality were examined with the use of multivariable logistic regression models. Baseline period for comparison was 1990-1993. The cohort (n=19 342; mean age, 74.2+/-13.2 years; 51.3% men) was followed until death or end of 2006. During the period of 1990-2005, age-standardized rates (per 100,000) of index hospitalization for HF as a principal diagnosis decreased from 191.0 to 103.2 in men, with an annual decrease of 3.5%, and from 130.5 to 75.1 in women, with an annual decrease of 3.1%. Risk-adjusted odds ratio of death at 30 days decreased to 0.73 (95% CI, 0.65 to 0.81) based on nonelective admissions. Risk-adjusted odds ratio of 1-year mortality also decreased during the study period in both genders and across all age groups. The total number of HF hospitalizations increased, with nonelective admissions increasing by 14.9% (P for trend, <0.0001) during this period. However, age-standardized rates of nonelective HF hospitalizations decreased during the same period., Conclusions: During the 16-year period studied, the incidence of index hospitalization for HF in Western Australia decreased steadily in both genders. However, hospitalizations for HF as a measure of health service use increased, despite decreasing rates, partly because of an aging population and improved HF survival.

Background: The population incidence of coronary heart disease (CHD) has been declining in Australia and many other countries. This decline has been due to reduced population levels of risk factors for CHD and improved medical care for those at higher risk of CHD. However, there are signs that there may be a slowing down or even reversal in the decline of CHD incidence due to the 'obesity epidemic' and other factors and this will have implications for the requirements for surgical treatments for those with CHD., Methods: Using a validated Markov simulation model applied to the population of Western Australia, different CHD incidence trend scenarios were developed to explore the effect of changing CHD incidence on requirements for coronary artery bypass graft (CABG) and percutaneous coronary interventions (PCI), together known as coronary artery revascularization procedures (CARPs)., Results: The most dominant component of CHD incidence is the risk of CHD hospital admission for those with no history of CHD and if this risk leveled off and the trends in all other risks continued unchanged, then the projected numbers of CABGs and PCIs are only minimally changed. Further, the changes in the projected numbers remained small even when this risk was increased by 20 percent (although it is an unlikely scenario). However, when the other CHD incidence components that had also been declining, namely, the risk of CABG and that of CHD death for those with no history of CHD, were also projected to level off as these were declining in 1998-2000 and the risk of PCI for those with no history of CHD (which was already increasing) was projected to further increase by 5 percent, it had a substantial effect on the projected numbers of CARPs., Conclusion: There needs to be dramatic changes to several CHD incidence components before it has a substantial impact on the projected requirements for CARPs. Continued monitoring of CHD incidence and also the mix of initial presentation of CHD incidence is required in order to understand changes to future CARP requirements.

Introduction: In spite of the mounting interest in the nexus between erectile dysfunction (ED) and cardiovascular (CV) diseases, there is little published information on the role of ED as a predictor for subsequent CV events., Aim: This study aimed to investigate the role of ED as a predictor for atherosclerotic CV events subsequent to the manifestation of ED. Method. The investigation involved the retrospective study of data on a cohort of men with ED linked to hospital morbidity data and death registrations. By using the linked data, the incidence rates of atherosclerotic CV events subsequent to the manifestation of ED were estimated in men with ED and no atherosclerotic CV disease reported prior to the manifestation of ED. The risk of subsequent atherosclerotic CV events in men with ED was assessed by comparing these incidence rates with those in the general male population., Main Outcome Measure: Standardized incidence rate ratio (SIRR), comparing the incidence of atherosclerotic CV events subsequent to the manifestation of ED in a cohort of 1,660 men with ED to the incidence in the general male population., Results: On the basis of hospital admissions and death registrations, men with ED had a statistically significantly higher incidence of atherosclerotic CV events (SIRR 2.2; 95% confidence interval 1.9, 2.4). There were significantly increased incidence rate ratios in all age groups younger than 70 years, with a statistically highly significant downward trend with increase of age (P < 0.0001) across these age groups. Younger age at first manifestation of ED, cigarette smoking, presence of comorbidities and socioeconomic disadvantage were all associated with higher hazard ratios for subsequent atherosclerotic CV events., Conclusions: The findings show that ED is not only significantly associated with but is also strongly predictive of subsequent atherosclerotic CV events. This is even more striking when ED presents at a younger age.

Objective: To examine trends in long term survival in patients alive 28 days after myocardial infarction and the impact of evidence based medical treatments and coronary revascularisation during or near the event., Design: Population based cohort with 12 year follow-up., Setting: Perth, Australia., Participants: 4451 consecutive patients with a definite acute myocardial infarction according to the World Health Organization MONICA (monitoring trends and determinants in cardiovascular disease) criteria admitted to hospital during 1984-7, 1988-90, and 1991-3., Main Outcome Measures: All cause mortality identified from official mortality records and the hospital morbidity data, with death from cardiovascular disease as a secondary end point., Results: In the 1991-3 cohort, 28 day survivors of acute myocardial infarction had a 7.6% absolute event reduction (95% confidence interval 4% to 11%) or a 28% lower relative risk reduction (16% to 38%), unadjusted for risk of death, over 12 years after the incident admission compared with the 1984-7 cohort, similar to the survival of the 1988-90 cohort. The improved survival for the 1991-3 cohort persisted after adjustment for demographic factors, coronary risk factors, severity of disease, and event complications with an adjusted relative risk reduction of 26% (14% to 37%), but this was not apparent after further adjustment for medical treatments in hospital and coronary revascularisation procedures within 12 months of the incident myocardial infarction., Conclusion: The improving trends in 12 year survival after a definite acute myocardial infarction are associated with progressive use of evidence based treatments during the initial admission to hospital and in the 12 months after the event. These changes in the management of acute myocardial infarction are probably contributing to the continuing decline in mortality from coronary heart disease in Australia.

Objective: To determine the accuracy of the hospital discharge coding of heart failure (HF) in the Western Australian (WA) Hospital Morbidity Data (HMD)., Methods: A retrospective medical chart review of a sample of 1,006 patients with a principal diagnosis code indicating HF in the WA HMD was undertaken. Validation was reported against a written diagnosis of HF in the medical chart and using Boston criteria score as a gold standard., Results: The positive predictive value (PPV) of the HMD coding of HF as the principal diagnosis was 99.5% when compared to the medical chart diagnosis and 92.4% when compared to the Boston score criteria for 'definite' HF and 98.8% for a combined 'possible' and 'definite' HF Boston score., Conclusions: With the high predictive accuracy, the WA HMD can be used with confidence to monitor trends in the epidemiology of in-hospital HF patients.

Background: Blue asbestos was mined and milled at Wittenoom in Western Australia between 1943 and 1966., Methods: Nearly 7000 male workers who worked at the Wittenoom mine and mill have been followed up using death and cancer registries throughout Australia and Italy to the end of 2000. Person-years at risk were derived using two censoring dates in order to produce minimum and maximum estimates of asbestos effect. Standardised mortality ratios (SMRs) compare the mortality of the former Wittenoom workers with the Western Australian male population., Results: There have been 190 cases of pleural and 32 cases of peritoneal mesothelioma in this cohort of former workers at Wittenoom. Mortality from lung cancer (SMR = 1.52), pneumoconiosis (SMR = 15.5), respiratory diseases (SMR = 1.58), tuberculosis (SMR = 3.06), digestive diseases (SMR = 1.47), alcoholism (SMR = 2.24) and symptoms, signs and ill defined conditions (SMR = 2.00) were greater in this cohort compared to the Western Australian male population., Conclusion: Asbestos related diseases, particularly malignant mesothelioma, lung cancer and pneumoconiosis, continue to be the main causes of excess mortality in the former blue asbestos miners and millers of Wittenoom.

Background: Limited data are available on the epidemiology of heart failure (HF) after acute myocardial infarction (AMI). We have investigated trends in the incidence and outcome of HF developing more than 28 days after first-ever AMI., Methods and Results: We identified all residents of Perth, Western Australia aged 25-64 years with no history of HF, who had experienced an AMI between 1984 and 1993, and followed them to 2005 (at which time survivors of the index events would have been aged up to 85 years). Of 3109 patients identified, 406 (13.1%) had at least one subsequent admission to hospital with a diagnosis of HF and 211 died. Following adjustment for age and sex, the hazard ratio for late-onset HF for the period 1989-1993 relative to 1984-1988 was 0.85 (95%CI: 0.69 to 1.04). After adjustment for age, history of diabetes and recurrent acute coronary syndrome, the hazard ratio for death in patients with late-onset HF did not change over the period of study (HR per year=1.02, 95%CI: 0.99 to 1.05)., Conclusion: Our findings contradict recent claims that there is an epidemic of HF driven in part by improved survival after AMI.

Use of troponin testing in the diagnosis of myocardial infarction substantially increases the number of cases diagnosed as myocardial infarction among suspected cases in comparison with previous criteria. However, the impact of troponin testing on rates reported in national statistics that use routinely collected hospital morbidity data is uncertain. The authors developed Poisson regression models to estimate the effect of troponin testing on long-term trends in hospital admission rates in Perth, Western Australia, from 1980 to 2004. Troponin tests were used for 10.5% of patients with suspected myocardial infarction in 1996, rising rapidly to more than 90% of patients from 2001 onward. Fitted models that assumed a continuing linear decline estimated that 100% use of troponin testing in cases of suspected myocardial infarction would lead to an apparent increase in hospital admission rates of 42% (95% confidence interval (CI): 28, 56) in men and 21% (95% CI: 4, 41) in women as compared with rates that would be expected if previous linear trends had continued. Smaller effects of 30% (95% CI: 14, 48) in men and -2% (95% CI: -21, 20) in women were found in fitted models that assumed an underlying attenuating trend in the rates. Similarly constructed logistic regression trend models found no significant effect of troponin testing on trends in 28-day case-fatality.

Aims: To investigate whether, over the 21 year period 1980-2001, there had been a reduction in the risk of repeat revascularisation or death from cardiovascular disease in the cohort of all patients who were treated by coronary revascularisation in Western Australia., Setting: State of Western Australia., Patients: All patients treated by coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) between 1980 and 2001., Design: Cohort study., Main Outcome Measures: Risk of repeat coronary artery revascularisation procedures (CARP) and risk of death from cardiovascular disease after first CARP., Results: After a CABG procedure, the two year risk of repeat revascularisation remained low (less than 2%) across the period 1980-2001. For PCI, however, this risk declined significantly from 33.6% in 1985-9 to 12.4% in 2000-1. The risk of death from cardiovascular disease after a CARP declined by about 50% between 1985 and 2001., Conclusions: Outcomes such as the risk of repeat revascularisation and the risk of death from cardiovascular disease have improved significantly for patients who underwent CARPs across the period 1980-2001. This has occurred despite an increasing trend in first CARP rates among older people and those with a recent history of myocardial infarction.

Objectives: To describe trends in the use of coronary artery revascularisation procedures (CARPs) and to determine whether or when CARP rates will stabilise., Setting: State of Western Australia., Patients: All patients treated by coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) between 1980 and 2001., Design: Descriptive study., Main Outcome Measures: Age standardised rates of first and total CARPs, CABGs, and PCIs., Results: Overall rates for both total and first CARPs among men and women rose steeply from 1980 to 1993, when they abruptly stabilised or actually started to decline. Rates in age groups under 65 years tended to rise earlier in the period and remained relatively flat, while rates for people over the age of 75 years started to rise later and were still increasing at the end of the study., Conclusions: Despite continuing increases in capacity to perform both CABG and PCI in Western Australia and evidence of continuing increases in the use of CARPs in the elderly population, rates appear to have stabilised for the first time since they were introduced.

Objective: To compare the risk of death in a cohort of Western Australian released prisoners with the risk experienced by the general population of Western Australia., Methods: A cohort study of prisoners in Western Australia whose last date of release ranged from 1 January 1994 to 1 January 1999. Overall mortality and cause of death were determined by data linkage to the Registrar General's record of deaths., Results: Aboriginal prisoners had a significantly lower survival rate after release than non-Aboriginal prisoners (p < 0.0001). When compared with their peers in the Western Australian community, both Aboriginal and non-Aboriginal prisoners were found to have an increased relative risk of death. Female non-Aboriginal released prisoners aged between 20 and 40 years were 17.8 (95% CI 8.1-27.5) times more likely to die than other female non-Aboriginals in Western Australia in the same age range. Male non-Aboriginal prisoners aged 20-40 years were 6.3 (95% CI 5.2-7.4) times more likely to die than their counterparts in the WA community. Female Aboriginal released prisoners were 3.4 (95% CI 1.2-5.6) times more likely to die than their peers, while male Aboriginal released prisoners were 2.9 (95% CI 2.2-3.5) times more likely to die. In their first six months after release, female non-Aboriginal prisoners aged 20 to 40 years were 69.1 (95% CI 17.9-120.3) times more likely to die than their counterparts in the WA community. The main causes of excess death were related to drug and alcohol abuse., Conclusion: All prisoners were at greater than expected relative risk of death after release from prison, with female non-Aboriginal prisoners at particularly high relative risk.

Objectives: To introduce the Western Australian Health Services Research Linked Database as infrastructure to support aetiologic, utilisation and outcomes research. To compare the study population, data resources, technical systems and organisational supports with international best practice in record linkage and health research., Method and Results: The WA Linked Database systematically links the available administrative health data within an Australian State of 1.7 million people. It brings together, initially, six core data elements (birth records, midwives' notifications, cancer registrations, in-patient hospital morbidity, in-patient and public out-patient mental health services data and death records). It will be updated regularly and is designed, in future extensions, to include data on primary, residential and domiciliary care and health surveys. Linkage uses probabilistic matching of patient names and other identifiers. Geocodes for spatial analysis are assigned using address linkage and mapping software. By June 1997, the project had taken 2 1/2 years to develop the system and link seven million core data records from 1980 to 1995., Conclusions: The system is consistent with international benchmarks, from four centres of excellence, for the study population, core datasets, matching and geocoding, and collaborative networks. There are prospects to redress deficiencies in primary medical contact and other data resources, validation studies, tracing systems and a more supportive legal framework., Implications: The WA Linked Database will be used in combination with medical record audits to provide a comprehensive evaluation of health system performance.

Laparoscopic cholecystectomy was introduced to Western Australia in 1991 and has become the method of choice for this procedure, although there are concerns about complications, particularly bile duct injuries. Previous studies have investigated this problem but have not confirmed the accuracy of coded information. We used Record Linkage to link operative admissions to subsequent admissions for all people who underwent cholecystectomy between 1988 and 1994. Using ICD9-CM discharge codes, we identified patients with an associated complication. We validated these patients' medical notes to obtain the proportion of complications in the period encompassing the introduction of laparoscopic cholecystectomy. We found 48 bile duct injuries in 413 patients. Of these 43% were found using complication codes on the operative admission, 79% using linked records of subsequent admissions, and 90% by adding lists of complicated cases from the three teaching hospitals. Any epidemiological research that uses surgical complication codes from operative admissions, particularly in the absence of a specific ICD9-CM code, will lead to significantly underestimating the prevalence of complications. By using record linkage, and validating medical records, we captured a significant proportion of complications.

This study aimed to estimate exposure-response relationships for mesothelioma and environmental exposure to crocidolite. All 4,659 former residents of Wittenoom, Western Australia (WA) who lived there between 1943 and 1993 for at least 1 mo and were not directly employed in the crocidolite industry, were followed-up through the WA death, cancer and mesothelioma registries, electoral rolls, and telephone books. In 1992, all subjects who should be traced were sent a questionnaire. Exposure levels were estimated from results of periodic environmental surveys and duration of residence. Incidence rates were standardized to the World Population and Cox Regression was used to estimate the effects of exposure on incidence. To the end of 1993, 27 cases of mesothelioma were diagnosed. Mesothelioma cases stayed longer at Wittenoom, had a higher average intensity of exposure, and a higher cumulative exposure to crocidolite than control subjects. The standardized incidence of mesothelioma was 260 per million person-years, and was similar for males and females. The rate increased significantly with time from first exposure, duration of exposure and cumulative exposure. At these levels of crocidolite exposure, there is a significantly increased risk of mesothelioma, which is dose-dependent.

Objectives: To estimate the relations between exposure to both tobacco smoke and crocidolite and the incidence of various histological types of lung cancer., Methods: In 1979 all former workers from the Wittenoom asbestos industry who could be traced were sent a questionnaire on smoking history. Of 2928 questionnaires sent, satisfactory replies were received from 2400 men and 149 women. Of the men, 80% had smoked at some time and 50% still smoked. Occupational exposure to crocidolite was known from employment records and follow up was maintained through death and cancer registries in Australia with histological diagnoses obtained from the relevant State Cancer Registry. Conditional logistic regression was used to estimate the effects of tobacco and asbestos exposure on incidence of different cell types of lung cancer in a nested case-control design., Results: Between 1979 and 1990, 71 cases of lung cancer occurred among men in this cohort: 27% squamous cell carcinoma, 31% adenocarcinoma, 18% small cell carcinoma, 11% large cell carcinoma, and 13% unclassified or indeterminate. Two of the classified cases and one unclassified case had never smoked. The incidence of both squamous and adenocarcinoma types of lung cancer were greatest in ex-smokers and in those subjects with the highest levels of exposure to crocidolite. After adjustment for smoking habit, the increase in incidence of lung cancer with increasing exposure to crocidolite was greater for squamous cell carcinoma than for adenocarcinoma., Conclusions: The results from this study have shown significant exposure-response effects for exposure to crocidolite, and both adenocarcinoma and squamous cell carcinoma of the lung. They also provide some further evidence against the theory that parenchymal fibrosis induced by asbestos is a necessary precursor to asbestos induced lung cancer.

The community of Busselton in Western Australia has participated in repeated cross-sectional health surveys and other health interventions since 1966. Health surveys of adults were conducted every three years from 1966 to 1981. Health interventions, including programs for high blood pressure, smoking, high blood cholesterol levels and obesity, were implemented in the community. Mortality rates for the Busselton area are compared with rates for the remainder of the southwest region of Western Australia in an attempt to determine if the surveys and associated interventions have had any impact on survival. Statistical comparisons via Poisson regression analysis showed that mortality rates for males over the period 1965 to 1989 in Busselton declined at a similar rate to the southwest. However, for females, especially those aged 45 to 74 years, mortality rates declined significantly faster in Busselton than in the southwest, suggesting a beneficial impact on survival of the surveys and associated interventions.

Objectives: To find (a) whether data available shortly after admission for acute myocardial infarction can provide a reliable prognostic indicator of survival at 28 days, and (b) whether such an indicator might be used to identify patients at low risk of death and suitable for early discharge., Design: Retrospective analysis of data collected on patients admitted to a coronary care unit for acute myocardial infarction. A validation sample was selected at random from these patients., Setting: Coronary care units in Perth, Western Australia., Subjects: 6746 patients aged under 65 and resident in the Perth Statistical Division who during 1984-92 were admitted to a coronary care unit with symptoms of myocardial infarction., Main Outcome Measures: Sensitivity and specificity of several models for predicting survival at 28 days after myocardial infarction, and detailed performance characteristics of a particular model., Results: Patients with a pulse rate of 100 beats/min or less, aged 60 or under, and with symptoms typical of myocardial infarction, no past history of myocardial infarction or diabetes, and no significant Q wave in the admission electrocardiogram had a very high chance of survival at 28 days (99.2%). These patients made up one third of all patients studied., Conclusion: The prognostic index identifies patients very soon after admission who are at low risk of death and potentially eligible for early discharge from hospital or the coronary care unit. Computing the index does not need complex cardiac investigations.

To determine the magnitude of the population at risk from non-occupational exposure to crocidolite at Wittenoom, Western Australia (WA), a cohort of 4,890 residents who never worked for the mining company Australian Blue Asbestos (ABA) has been assembled from all 18,553 available records: the local school register, hospital attendances, the WA electoral roll, birth certificates, workers who answered a mailed questionnaire in 1979, participants in a cancer-prevention programme using vitamin-A dietary supplements, and other sources. The majority of subjects were relatives and friends of ABA employees, and nearly half the cohort were either born at Wittenoom or first went there as children under 10 years of age. As most residents were at Wittenoom when the mine and mill were in operation during the period 1943 to 1966, 82% were first exposed to crocidolite 20 or more years ago. The proportion of other workers (i.e., not employed by ABA) and their families increased once the mining operations ceased. To date, 24 cases of mesothelioma have been reported in this cohort: 9 males and 15 females. Time from first exposure to diagnosis ranged from 23 to 44 years and residence in Wittenoom ranged from 6 weeks to 11 years.

Type of Study: Descriptive study of trends in the drug therapy for acute myocardial infarction., Setting: Population-based register of acute coronary events compiled for the years 1984 to 1990 in the course of the Perth MONICA project., Cases: 5294 cases meeting clinical criteria for acute myocardial infarction., Results: Striking changes were seen in the use of aspirin before admission to hospital (from 4% to 18%). During the stay in hospital the use of beta-blockers increased steadily from 52% to 76%, while the use of aspirin increased 3.5-fold from 25% to 88% and the use of streptokinase increased 13.5-fold from 2.4% to 32.4%. The proportion of patients prescribed beta-blockers on discharge from hospital increased from 46% to 65% and that for aspirin rose from 16% to 83%. There were also major relative increases in the use of lipid-lowering agents and declines in the use of antiarrhythmic drugs., Conclusion: These trends in the pharmacological management of myocardial infarction mirror the emerging evidence from clinical trials, although the increases in the use of certain types of drugs antedated publication of the results of major randomised studies. The changes in therapy would partly explain observed improvements in case fatality and may have contributed to the decline in coronary mortality observed in the Perth community.

In 1979 all former workers from the Wittenoom asbestos industry who could be traced to an address were sent a questionnaire to determine smoking history. Occupational exposure to crocidolite was known from employment records. Of 2928 questionnaires sent, satisfactory replies were received from 2400 men and 149 women. Eighty per cent of these had smoked at some time and 50% were still smoking. Since that time 40 cases of lung cancer and 66 cases of compensatable asbestosis have occurred in this cohort. The incidence of both lung cancer and asbestosis was greatest in those subjects with the highest levels of exposure to crocidolite and in ex-smokers. Statistical modelling of the joint effects of these exposures on the incidence of each disease indicated that crocidolite exposure multiplied the rates of lung cancer due to smoking and that smoking has no measurable effect on the rates of asbestosis. There was also some evidence that the incidence rate of lung cancer is falling with time.

Objective: To see whether patients taking an oral beta blocker at the time of admission to hospital with myocardial infarction have a reduced risk of death at 28 days., Design: Retrospective analysis of data collected on patients admitted over four years., Setting: Community based study., Patients: 2430 Consecutive patients living in the Perth statistical division admitted to hospital with myocardial infarction during 1984-7., Main Outcome Measure: Survival at 28 days among patients taking a beta blocker at onset of myocardial infarction., Results: Patients were grouped into those who were and were not taking a beta blocker at the time of admission. Though patients taking a beta blocker were older and more likely to have a history of myocardial infarction, angina, or hypertension, the overall mortality at 28 days was similar in the two groups. A logistic regression model used to adjust for factors predictive of cardiac death at 28 days confirmed that patients taking a beta blocker at the time of admission had a significantly reduced risk of death (relative risk 0.50; 95% confidence interval 0.34 to 0.76). Though the incidence of fatal ventricular fibrillation was similar in the two groups, mean peak creatine kinase activity was significantly lower in the beta blocker group., Conclusions: These data support the value of long term use of beta blockers in patients at risk of myocardial infarction. They suggest that patients taking these agents before admission to hospital with myocardial infarction have a significant survival advantage at 28 days, which may be due to a reduction in infarct size.

The separate and combined effects of duration and intensity of exposure to crocidolite on mortality from lung cancer, malignant mesothelioma, and stomach cancer were examined in 6506 male former crocidolite miners and millers at Wittenoom Gorge, Western Australia. Each subject who had died from lung cancer (92), mesothelioma (31), or stomach cancer (17) was matched with up to 20 control subjects of the same age who were not known to have died before the index subject. Relations of dose and time of exposure to crocidolite to risk of death were modelled by conditional logistic regression. For lung cancer, the best fitting multiplicative model was one which estimated a relative risk (RR) of 1.12 (95% CI 1.04-1.20) per year of exposure and 1.01 (95% CI 1.00-1.01) per fibre/ml. This was statistically indistinguishable from an additive model showing an increase in RR of 0.01045 (95% CI 0.008-0.020) per f/ml year. For mesothelioma the best fitting model appeared to be one estimating a RR of 24.9 (95% CI 3.51-1.77) per log year since first exposed and a RR of 10.5 (95% CI 3.12-35.1) if exposed for longer than six months. This was not distinguishable statistically from a model that showed mortality increasing as the fourth power of time since first exposed less the fourth power of time since last exposed. The effect of intensity of exposure on the RR for mesothelioma was only slight. There was no consistent effect of any measure of exposure to crocidolite on death from stomach cancer.

Trends in the incidence of and mortality from myocardial infarction in Perth, Western Australia, were studied for the period 1971 to 1982. The estimated age-adjusted incidence rate of myocardial infarction fell by 24% in males and 37% in females over this period. The rate fell in each of six age-sex groups, but the proportional decrease in those aged less than 45 years was nearly double that in those aged 45 years and over, as it was in females compared with males and in fatal cases compared with nonfatal cases. Over 80% of the decline in mortality was in deaths outside hospital. This and seven other comparable studies all showed a net decrease in the estimated incidence of myocardial infarction in both sexes, with median annual decreases of 2% in males and 3% in females. It is concluded that the decline in the incidence of myocardial infarction contributed substantially to the observed decrease in ischemic heart disease mortality, and that the most plausible explanation for the decline in incidence is a reduction in the prevalence of risk factors for myocardial infarction.

In a cohort of 6502 male and 410 female former workers from the crocidolite (blue asbestos) mining and milling works at Wittenoom, Western Australia, there were 94 cases of malignant mesothelioma (12 cases of peritoneal mesothelioma), 141 cases of lung cancer and 356 successful compensation claims for asbestosis to the end of 1986. After adjusting for measured covariate effects by means of proportional hazards regression analysis, smooth curves were fitted to the resulting "underlying" incidence rates for malignant mesothelioma, lung cancer and asbestosis, separately, and for mortality of any cause. By the use of these curves and individual risk estimates, predictions have been made of the future incidence of these diseases to the year 2020. With the assumption that all subjects who were not known to be dead or departed overseas still were alive at December 31, 1986, and excluding persons of more than 85 years of age, the number of new cases of mesothelioma is expected to rise to a peak of around 25 cases per year in 2010, with an expected total number of 692 cases of mesothelioma (95% confidence interval [CI], 394-990 cases) between 1987 and 2020. A total of 2898 deaths (95% CI, 2284-3511 deaths) of any cause is expected in the same period. New cases of lung cancer and asbestosis are expected to continue at roughly the current rates of eight and 17 cases per year, respectively, before declining after the year 2000, leading to totals of 183 cases (95% CI, 34-335 cases) and 482 cases (95% CI, 236-728 cases), respectively, being expected by the year 2020. Predictions that were based on the censoring of subjects at the date that they last were known to be alive resulted in slightly higher, but probably less accurate, estimates.

It is known that 6505 men and 411 women were employed in the mining and milling of crocidolite at Wittenoom in the Pilbara region of Western Australia between 1943 and 1966. Employment was usually brief (median duration four months) and exposure intense (median estimated cumulative exposure 6 fibres/cc years). The vital status of 73% of the men and 58% of the women employed in the industry was known at 31 December 1980, providing 95 264 person-years of follow up with 820 deaths in men and 4914 person-years with 23 deaths in women. The standardised mortality ratio (SMR) for all causes in men was 1.53 (95% confidence interval 1.43 to 1.64). Statistically significant excess death rates were observed in men for neoplasms, particularly malignant mesothelioma (32 deaths), neoplasms of the trachea, bronchus, and lung (SMR 2.64), and neoplasms of the stomach (SMR 1.90); respiratory diseases, particularly pneumoconiosis (SMR 25.5); infections, particularly tuberculosis (SMR 4.09); mental disorders particularly alcoholism (SMR 4.87); digestive diseases, particularly peptic ulceration (SMR 2.46) and cirrhosis of the liver (SMR 3.94); and injuries and poisonings, particularly non-transport accidents (SMR 2.36). The excess mortality from pneumoconiosis, malignant mesothelioma, and respiratory cancers, but not stomach neoplasms, was dependent on time since first exposure and cumulative exposure. There was no increase in mortality from laryngeal cancer (SMR 1.09) or neoplasms other than those listed. The SMR for all causes in women was 1.47 (95% confidence interval 0.98-2.21) and for neoplasms 1.99; there was one death from malignant pleural mesothelioma.

Variations in the ratio of "definite" to "possible" myocardial infarction for non-fatal cases were examined in studies that used World Health Organization criteria. There were large variations in this ratio, variations which appeared to be due to differences in the ascertainment of non-fatal cases of "possible" myocardial infarction, which, in turn, contributed to reported differences in the incidence of myocardial infarction. A significant proportion of cases of "possible" myocardial infarction probably do not have ischemic heart disease at all, since, in our data, cases of "possible" myocardial infarction (non-fatal) with a hospital discharge diagnosis of chest pain (undiagnosed) had a risk of death that was no worse than that in the general population. Thus the most reproducible, and possibly most accurate estimates of the incidence of myocardial infarction may come from including only fatal cases of "possible" myocardial infarction with both fatal and non-fatal cases of "definite" myocardial infarction.