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.

Variable effects of prevalence correction of population denominators on differentials in myocardial infarction incidence: a record linkage study in Aboriginal and non-Aboriginal Western Australians.

OBJECTIVES: To investigate the impact of prevalence correction of population denominators on myocardial infarction (MI) incidence rates, rate ratios, and rate differences in Aboriginal vs. non-Aboriginal Western Australians aged 25-74 years during the study period 2000-2004. STUDY DESIGN AND SETTING: Person-based linked hospital and mortality data sets were used to estimate the number of prevalent and first-ever MI cases each year from 2000 to 2004 using a 15-year look-back period. Age-specific and -standardized MI incidence rates were calculated using both prevalence-corrected and -uncorrected population denominators, by sex and Aboriginality. RESULTS: The impact of prevalence correction on rates increased with age, was higher for men than women, and substantially greater for Aboriginal than non-Aboriginal people. Despite the systematic underestimation of incidence, prevalence correction had little impact on the Aboriginal to non-Aboriginal age-standardized rate ratios (6% and 4% underestimate in men and women, respectively), although the impact on rate differences was more marked (12% and 6%, respectively). The percentage underestimate of differentials was greater at older ages. CONCLUSION: Prevalence correction of denominators, while more accurate, is difficult to apply and may add modestly to the quantification of relative disparities in MI incidence between populations. Absolute incidence disparities using uncorrected denominators may have an error >10%.

Incidence of and case fatality following acute myocardial infarction in Aboriginal and non-Aboriginal Western Australians (2000-2004): a linked data study.

BACKGROUND: Despite Coronary Heart Disease exacting a heavy toll among Aboriginal Australians, accurate estimates of its epidemiology are limited. This study compared the incidence of acute myocardial infarction (AMI) and 28-day case fatality (CF) among Aboriginal and non-Aboriginal Western Australians aged 25-74 years from 2000-2004. METHODS: Incident (AMI hospital admission-free for 15 years) AMI events and 28-day CF were estimated using person-based linked hospital and mortality data. Age-standardised incidence rates and case fatality percentages were calculated by Aboriginality and sex. RESULTS: Of 740 Aboriginal and 6933 non-Aboriginal incident events, 208 and 2352 died within 28 days, respectively. The Aboriginal age-specific incidence rates were 27 (males) and 35 (females) times higher than non-Aboriginal rates in the 25-29 year age group, decreasing to 2-3 at 70-74 years. The male:female age-standardised incidence rate ratio was 2.2 in Aboriginal people 25-54 years compared with 4.5 in non-Aboriginal people. Aboriginal age-standardised CF percentages were 1.4 (males) and 1.1 (females) times higher at age 25-54 years and 1.5 times higher at age 55-74 years. CONCLUSION: These data suggest higher CF and, more importantly, AMI incidence contribute to the excess ischaemic heart disease mortality in Aboriginal Western Australians. The poorer cardiovascular health in Aboriginal women, particularly in younger age groups, should be investigated.

Impact of laparoscopic cholecystectomy on hospital utilization.

OBJECTIVE: The objective of the present study was to assess the impact of laparoscopic cholecystectomy (LC) and associated endoscopic retrograde pancreatography (ERCP) on hospital utilization. BACKGROUND: Laparoscopic cholecystectomy (LC) has resulted in marked reductions in average length of hospital stay; but population-based studies of hospital utilization have generally not taken into account increased cholecystectomy rates or associated increases in pre and postoperative admissions. METHODS: We conducted a population-based study of all residents of Western Australia who underwent cholecystectomy in the period 1980-2000. Record linkage was used to identify pre and postoperative admissions, and to estimate aggregate length of stay per case based on all relevant admissions. We estimated trends in cholecystectomy rates, proportions of cases with related pre and postoperative hospital admissions, average aggregate length of stay per case and total bed utilization per unit of population. RESULTS: The introduction of LC was associated with a sustained increase in rates of cholecystectomy of 25%. Similar increases occurred in the percentage of cases with related preoperative and postoperative admissions. Average length of stay for index admissions declined by nearly 60% compared with 50% for all related admissions. Per capita hospital utilization for index admissions decreased by 45% compared with 38% for index and associated admissions combined, and 32% for all admissions for biliary disease. CONCLUSIONS: Reduced hospital utilization associated with LC was partly offset by increases in pre and postoperative admissions and a sustained increase in cholecystectomy rates. Record linkage is required to assess the true impact of new technologies on hospital utilization.

Changing methods of imaging the common bile duct in the laparoscopic cholecystectomy era in Western Australia: implications for surgical practice.

OBJECTIVE: To assess changes in the use of endoscopic retrograde cholangiopancreatography (ERCP), intraoperative cholangiography (IOC), and surgical exploration of the common bile duct (CBD) associated with the introduction of laparoscopic cholecystectomy (LC). SUMMARY BACKGROUND DATA: The optimal strategy for dealing with potential stones of the CBD during LC remains controversial. METHODS: The authors conducted a population-based study of all cases of cholecystectomy (20,084) in Western Australia in the periods before, during, and after the introduction of LC (1988-1994). Index admissions were linked to previous or subsequent admissions for ERCP. Factors associated with ERCP were analyzed by multivariate regression models. RESULTS: Between 1988 and 1994, admissions for ERCP almost doubled, whereas the use of IOC decreased from 71% to 51%. Different trends were found for open and laparoscopic procedures. Exploration of the CBD declined because of the infrequent use of this procedure in LC. Preoperative ERCP was significantly more common in older patients and men; the reverse was found for IOC. There was an adjusted 3.5-fold increase in preoperative ERCP both during and after the introduction of LC. The adjusted odds ratios for IOC were 0.48 and 0.52 for these periods. CONCLUSIONS: The introduction of LC was associated with increasing reliance on ERCP to image the CBD and a decrease in the use of IOC. These changes were observed in both LC and open cholecystectomy. They suggest that the use of ERCP before cholecystectomy has partly replaced IOC for visualization of the CBD for suspected stones. Although more than 40% of patients undergoing LC had IOC, surgeons appear to be reluctant to perform surgical exploration of the CBD when stones are present. Savings in terms of both complications and cost can be expected if preoperative ERCPs performed for suspicion of uncomplicated CBD stones are replaced by IOC.