Acute Myocardial Infarction Case Fatality Research Articles

Ambient particulate matter and in-hospital case fatality of acute myocardial infarction: A multi-province cross-sectional study in China

The acute myocardial infarction (AMI) outcomes have been extensively linked with ambient particulate matter (PM). However, whether a smaller particle has greater impact and the consequent attributable burden associated with PM of different sizes remain unclear. We conducted a multi-province cross-sectional study among AMI patients using the inpatient discharge datasets from four Chinese provinces (Shanxi, Sichuan, Guangxi, and Guangdong) from 2014 to 2019. Ambient PM exposure for each patient was assessed using the ChinaHighAirPollutants dataset. We employed the mixed-effects logistic regression models to evaluate the association of PM of different sizes (PM1, PM2.5, PM10) on in-hospital case fatality. The potential reducible fractions in in-hospital case fatality were estimated through counterfactual analyses. Of 177,749 participants, 125,501 (70.6 %) were male and the in-hospital case fatality rate was 4.9%. For short-term (7-day average) exposure, the odds ratios (ORs) for PM1, PM2.5, and PM10 (per 10 µg/m3) were 1.052 (95 % confidence interval [CI], 1.032–1.071), 1.026 (95 % CI, 1.014–1.037), and 1.016 (95% CI, 1.008–1.024), respectively. The estimated ORs for long-term exposure (annual average) were 1.303 (95 % CI, 1.252–1.356) for PM1, 1.209 (95 % CI, 1.178–1.241) for PM2.5, 1.157 (95 % CI, 1.134–1.181) for PM10. Short-term exposure to PM1 showed the highest potential reducible fraction (8.5 %, 95 % CI, 5.0–11.7 %), followed by PM2.5 and PM10, while the greatest potential reducible fraction of long-term exposure was observed in PM10 (30.9 %, 95 % CI, 27.2–34.4%), followed by PM2.5 and PM1. In summary, PM with smaller size had a more pronounced impact on in-hospital AMI case fatality, with PM1 exhibiting greater effects than PM2.5 and PM10. Substantial health benefits for AMI patients could be achieved by mitigating ambient PM exposure.

Abstract 13615: Weekdays versus Weekends: Outcomes of Cardiogenic Shock in the Setting of Acute Myocardial Infarction

Introduction: Acute myocardial infarction (AMI) accounts for the majority of patients with cardiogenic shock (CS). The high case fatality justifies the need for an optimal hospital care system that is available 24 hours, 7 days a week. It is unclear whether the “weekend effect” has an impact on the outcome of CS associated with AMI. Hypothesis: Weekend CS-AMI admissions have a higher in-hospital case fatality than weekday admissions. Methods: A total of 22,632 patients with ST segment elevation AMI complicated with CS between the years 1986 to 2015 were identified in the Myocardial Infarction Data Acquisition System, a statewide database of all admissions to non-federal hospitals in NJ. Trend analysis was performed using a logistic regression model with admission year as a continuous variable. Case fatality rates between weekend vs weekday admissions were compared using the Cochran–Mantel–Haenszel test, stratifying by admission year. Results: From 1986 to 2015 there was a steady decline in the rates of in-hospital case fatality of AMI complicated with CS, from 79% to 33% (p< 0.001). The overall CS death rate for admissions on weekends was 61% and for weekdays 59% (Common-Odds Ratio = 1.10 (95% CI (1.02-1.17) p= 0.006) (figure). The use of mechanical circulatory support (MCS) was lower on weekends (p<0.001) and was associated with a higher case fatality rate 48 hours from admission (p<0.001). Conclusion: Deaths related to CS complicating AMI have steadily declined and this applies for both, patients admitted on weekends and weekdays. There was a higher hospital death rate in patients admitted over weekends compared to weekdays. The underutilization of MCS devices during weekends likely contributes to the difference in case fatality between weekends and weekdays.

Relation Between Statewide Hospital Performance Reports on Myocardial Infarction and Cardiovascular Outcomes

Healthcare systems may be judged on quality of care and access to health services. Studies on the association of hospital quality of care scores and clinical outcomes have yielded mixed results. With the help of a richer and more representative database, the aim of our study was to shed light on these inconsistencies. We examined the association of 4 process of care scores (prescription of aspirin, β blocker, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker used for left ventricular systolic dysfunction, and an overall composite score) for acute myocardial infarction (AMI), reported in the Hospital Performance Reports, with 30-day and 1-year rates of readmission for AMI and cardiovascular (CV) death. Clinical outcomes were from the Myocardial Infarction Data Acquisition System, an administrative database that comprises all patient CV disease admissions to acute care hospitals in New Jersey. CV death was related with overall score (adjusted odds ratio [OR] 0.821, 95% confidence interval [CI] 0.726 to 0.930, p = 0.002) at 30 days and with all 4 scores at 1 year (OR ranging from 0.829 to 0.997, p <0.01). Readmission due to AMI was associated with the overall score (OR 0.789, 95% CI 0.691 to 0.902, p <0.0001) and the aspirin score (OR 0.995, 95% CI 0.990 to 1, p = 0.046) at 30 days. Low hospital performance scores for AMI were associated with increased CV death and readmission for AMI. In conclusion, healthcare providers should allocate their resources to improving hospital performance to decrease AMI case fatality, AMI readmissions, and CV-related healthcare spending.

Trends in incidence and case fatality of acute myocardial infarction, angina and coronary revascularisation in people with and without type 2 diabetes in Scotland between 2006 and 2015

Aims/hypothesisThe aim of the study was to examine trends in the incidence and case fatality of acute myocardial infarction (AMI) and in hospital admissions for angina and coronary revascularisation procedures in people with type 2 diabetes and in people without diabetes in Scotland between 2006 and 2015.MethodsIn this retrospective cohort study, AMI, angina and revascularisation event data were obtained for adults from hospital admissions and death records linked to a population-based diabetes register. Incidence by diabetes status was estimated using negative binomial models with adjustment or stratification by age, sex, deprivation and calendar year. Logistic regression was used to estimate AMI case fatality by diabetes status.ResultsThere were 129,926 incident AMI events, 41,263 angina admissions and 69,875 coronary revascularisation procedures carried out during 34.9 million person-years of follow-up. The adjusted incidence of AMI, angina and revascularisation procedures declined by 2.0% (95% CI 1.73%, 2.26%), 9.62% (95% CI 9.22%, 10.01%) and 0.35% (95% CI −0.09%, 0.79%) per year, respectively. The rate of decline did not differ materially by diabetes status. RRs of AMI for type 2 diabetes were 1.86 (95% CI 1.74, 1.98) for men and 2.32 (95% CI 2.15, 2.51) for women. Of the 77,211 people admitted to hospital with a first AMI, 7842 (10.2%) died within 30 days of admission. Case fatality was higher in people with type 2 diabetes than in people without diabetes and declined in both groups by 7.93% (95% CI 7.03%, 8.82%) per year.Conclusions/interpretationThe incidence of AMI, angina, revascularisation and AMI case fatality has declined over time, but the increased risk associated with type 2 diabetes has remained approximately constant.

Case-fatality after a hospitalization for acute coronary syndrome in 2015: A national study

Previous study described acute myocardial infarction case fatality in France in cardiac care unit but no recent study analyzed all hospitalized acute coronary syndrome with one year follow-up. The objectives of this study were to analyze very early to late case fatality rates in patients hospitalized for ACS in 2015 in France, their determinants and time-trends between 2010 and 2015. Data were extracted from the national health insurance information system. Hospitalisation for ACS were collected by using ICD-10 codes as primary discharge diagnosis for ST-elevation myocardial infarction (STEMI), other MI and unstable angina (UA). Multivariate Cox models adjusted for age, comorbidities, sex, previous ACS, social deprivation of the municipality of residence, invasive procedures and pharmacological treatment refund were used to assess determinants of case-fatality respectively at 3 day after hospital admission, 4–30 day and 31–365 day after excluding dead patients of the preceding periods. In 2015, 84,202 persons were hospitalized for ACS with 34.9% for STEMI, 20.5% for other MI and 44.7% for UA. Mean age were 65.2, 69.1 and 68.1 respectively. Cumulative 3-day, 30-day and 1-year case-fatality were 3.9%, 8.4% and 13.8% for STEMI, 2.7%, 6.5% and 14.4% for other MI, and 0.4%, 2.0% and 7.2% for UA. In multivariate analysis, female sex was associated with higher 3-day case-fatality among STEMI only, particularly < 65 years of age [HR = 1.47(1.30–1.68)]. Social deprivation was associated with an increase of all case-fatality outcomes. Additional adjustment for hospital management and medication delivery did not change the results. Case-fatality up to 1 year after a hospitalization for ACS remained non-negligible. Women seemed to be at particular risk of very early case-fatality. Social inequalities independently impacted all period outcomes. No significant change in ACS case fatality were found between 2010 and 2015.

Impact of a Partial Smoke-Free Legislation on Myocardial Infarction Incidence, Mortality and Case-Fatality in a Population-Based Registry: The REGICOR Study

Background and ObjectiveCoronary heart disease (CHD) is the leading cause of death, and smoking its strongest modifiable risk factor. Our aim was to determine the impact of the Spanish 2006 partial smoke-free legislation on acute myocardial infarction (AMI) incidence, hospitalization and mortality rates, and 28-day case-fatality in Girona, Spain.MethodsUsing a population-based registry (the REGICOR Study), we compared population incidence, hospitalization, and mortality rates, and 28-day case-fatality in the pre- and post-ban periods (2002–2005 and 2006–2008, respectively) by binomial regression analysis adjusted for confounding factors. We also analyzed the ban's impact on the outcomes of interest using the AMI definitions of the American Heart Association (AHA)/European Society of Cardiology (ESC) and the World Health Organization (WHO)-Monitoring trends and determinants in cardiovascular diseases (MONICA).ResultsIn the post-ban period, AMI incidence and mortality rates significantly decreased (relative risk [RR] = 0.89; 95% confidence interval [CI] = 0.81–0.97 and RR = 0.82; 95% CI = 0.71–0.94, respectively). Incidence and mortality rates decreased in both sexes, especially in women, and in people aged 65–74 years. Former and non-smokers (passive smokers) showed diminished incidence rates. Implementation of the ban was not associated with AMI case-fatality. Models tended to be more significant with the WHO-MONICA than with the AHA/ESC definition.ConclusionsThe 2006 Spanish partial smoke-free legislation was associated with a decrease in population AMI incidence and mortality, particularly in women, in people aged 65–74 years, and in passive smokers. These results clarify the association between AMI mortality and the enactment of a partial smoke-free legislation and reinforce the effectiveness of smoking regulations in preventing CHD.

Reducing case fatality from acute myocardial infarction in cienfuegos, Cuba, 1994-2009

Between 1994 and 2009, the Dr Gustavo Aldereguía University Hospital of Cienfuegos, Cuba implemented a series of interventions that reduced acute myocardial infarction case fatality rate from 47% to 15%. These interventions were part of an institutional plan for myocardial infarction included in the hospital's overall quality assurance strategy. Outcomes resulted primarily from organizational changes (from upgrading of the hospital emergency department and provincial emergency system to creation of a comprehensive coronary care unit and a chest pain center); optimizing use of effective drugs (streptokinase, aspirin, ACE inhibitors and beta blockers); adherence to clinical practice guidelines; and continual and participatory evaluation and adjustment.

Ambient Air Pollutants and Acute Case-Fatality of Cerebro-Cardiovascular Events: Takashima Stroke and AMI Registry, Japan (1988–2004)

Background: Apart from the conventional risk factors, cerebro-cardiovascular disease (CVD) are also reported to be associated with air pollution, thus lowering the level of exposure might contribute in prevention activities to reduce the associated adverse outcomes. Though few studies conducted in Japan have reported on the CVD mortality but none have explored the effect of air pollutant exposure on the acute case-fatality of CVD. We investigated the effects of air pollution exposure on acute case-fatality of stroke and acute myocardial infarction (AMI) in a setting where pollutant levels are rather low. Methods: We leveraged the data from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County located in central Japan. The study period of 6,210 days (16 years, leap years also taken into account) were divided into quartiles of daily average pollutant concentration; suspended particulate matter (SPM), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and photochemical oxidants (Ox). The stroke and AMI events were categorized to corresponding quartiles based on the pollution levels of the onset day. To study the effects of air pollutants, we estimated the fatality rate ratio across quartiles of the pollutants where the lowest quartile served as the reference. Results: There were 307 (men: 153 and women: 154) fatal stroke cases within 28 days of onset among the 2,038 first ever stroke during 1988–2004. In the same period, there were 142 (men: 94 and women: 54) fatal AMI cases within 28 days of onset among the 429 first ever AMI events. The mean of the measured pollutant levels were as follows: SPM 26.9 µg/m³, SO₂ 3.9 ppb, NO₂ 16.0 ppb, and Ox 28.4 ppb. Among the pollutants, higher levels of NO₂ showed increased fatality risk. In multi-pollutant model, the highest quartile of NO₂ was associated with 60% higher stroke case-fatality risk in comparison to lowest quartile of NO₂. In the fully adjusted model the fatality-rate ratio was 1.65 (95% CI 1.06–2.57). This association was more prominent among stroke subtype of cerebral infarction. Other pollutant levels did not show any association with stroke or AMI case-fatality. Conclusion: We observed association between NO₂ levels, an index of traffic related air pollution, with the acute case-fatality of stroke, especially cerebral infarction in our study population. Further studies are needed in different regions to determine the association between ambient air pollutants and acute cardiovascular fatalities.

Reducing Case Fatality from Acute Myocardial Infarction in Cienfuegos, Cuba, 1994–2009

Between 1994 and 2009, the Dr Gustavo Aldereguia University Hospital of Cienfuegos, Cuba implemented a series of interventions that reduced acute myocardial infarction case fatality rate from 47% to 15%. These interventions were part of an institutional plan for myocardial infarction included in the hospital's overall quality assurance strategy. Outcomes resulted primarily from organizational changes (from upgrading of the hospital emergency department and provincial emergency system to creation of a comprehensive coronary care unit and a chest pain center); optimizing use of effective drugs (streptokinase, aspirin, ACE inhibitors and beta blockers); adherence to clinical practice guidelines; and continual and participatory evaluation and adjustment.

Incidence and case fatality due to acute myocardial infarction in Chile in the period 2001-2007

Acute myocardial infarction (AMI) causes 73.6% of coronary heart disease (CHD) deaths in Chile. To estimate the incidence and case fatality of AMI and analyze their trends between 2001-2007. A time-series study analyzing all cases of AMI (according to the International Classification of Diseases (ICD)-10, I21 code), registered in the National Hospitalizations and Death databases. Annual incidence rates and case fatality by sex and age groups were calculated. The direct method was used to standardize rates by age, using the World Health Organization 2000 Population. Prais-Winsten regression models were used to evaluate trends, expressed as relative change. Between 2001 and 2007, we estimated that 83,754 cases of AMI occurred. Standardized annual incidence rate was 74.4 per 100,000 inhabitants (98.0 in men and 51.0 in women). Incidence rates increased by 34% in individuals < 45 years of age and 9.2% in the group 55-64 years (p < 0.001, both). Total case fatality was 49.5% (45.4% in men and 57.2% in women; p < 0.001), and its trend analysis showed a significant annual reduction of 1.2% in men and 0.81% in women. In-hospital case fatality was 14.2% (11.3 and 20.4% in men and women, respectively; p < 0.001). There was a significant annual reduction of mortality (0.57 and 1.01% in men and women, respectively (p < 0.05). The incidence of AMI was stable in the whole population, but increased in younger age groups. Total and in-hospital case-fatality decreased. Despite the greater reduction of case fatality in women, they still have a higher risk of dying while in hospital.

Trends in Q-wave acute myocardial infarction case fatality from 1978 to 2007 and analysis of the effectiveness of different treatments

We sought to analyze the trends in first Q-wave acute myocardial infarction (AMI) case fatality from 1978 to 2007 in a population-based hospital register, to determine the variables related to these changes, and to assess the effectiveness of current AMI management. Population-based hospital registry included patients with first Q-wave AMI aged 25 to 74 years admitted between 1978 and 2007. Sociodemographic and clinical characteristics, treatments, and procedures used during hospital stay, and 28-day case fatality were recorded. Logistic regression was used for multivariate analysis of six 5-year periods. The 30-year study included 3,982 patients. Mean 28-day case fatality was 8.96%, with a decreasing trend from 16.6% in the first 5-year period to 4.7% in the sixth (P for trend < .001). Study period was independently associated with case fatality. Case-fatality reduction attributable to pharmacologic treatments was 51% overall; in 24-hour survivors, pharmacologic treatments and broad use of invasive procedures explained 39% and 38%, respectively, of the difference between the observed case fatality in 2003-2007 and 1978-1982. A dramatic decrease in 28-day case fatality occurred during this 30-year period and was mainly related to the use of antiplatelet drugs, β-blockers, thrombolysis, and invasive procedures. These data support the current guidelines for the management of acute coronary syndrome.

P2-217 Trends in incidence and case-fatality of acute myocardial infarction in Chile, 2001–2007

IntroductionIn Chile, coronary heart disease is the main cause of death in men and the second in women. Acute Myocardial Infarction (AMI) causes 73.6% of coronary heart disease deaths registered...

Trends and inequalities in short-term acute myocardial infarction case fatality in Scotland, 1988-2004.

BackgroundThere have been substantial declines in ischemic heart disease in Scotland, partly due to decreases in acute myocardial infarction (AMI) incidence and case fatality (CF). Despite this, Scotland's IHD mortality rates are among the worst in Europe. We examine trends in socioeconomic inequalities in short-term CF after a first AMI event and their associations with age, sex, and geography.MethodsWe used linked hospital discharge and death records covering the Scottish population (5.1 million). Between 1988 and 2004, 178,781 of 372,349 patients with a first AMI died on the day of the event (Day0 CF) and 34,198 died within 28 days after surviving the day of their AMI (Day1-27 CF).ResultsAge-standardized Day0 CF at 30+ years decreased from 51% in 1988-90 to 41% in 2003-04. Day1-27 CF decreased from 29% to 18% over that period. Socioeconomic inequalities in Day0 CF existed for both sexes and persisted over time. The odds of case fatality for men aged 30-59 living in the most deprived areas in 2000-04 were 1.7 (95%CI: 1.3-2.2) times as high as in the least deprived areas and 1.9 (1.1-3.2) times as high for women. There was little evidence of socioeconomic inequality in Day1-27 CF in men or women. After adjustment for socioeconomic deprivation, significant geographic variation still remained for both CF definitions.ConclusionsA high proportion of AMI incidents in Scotland result in death on the day of the first event; many of these are sudden cardiac deaths. Short-term CF has improved, perhaps reflecting treatment advances and reductions in first AMI severity. However, persistent socioeconomic and geographic inequalities suggest these improvements are not uniform across all population groups, emphasizing the need for population-wide primary prevention.

The effect of early life factors on 28 day case fatality after acute myocardial infarction

To study the association of size at birth and social circumstances at birth with 28 day case fatality of acute myocardial infarction (AMI). Based on 1,776 first cases of AMI occurring in Uppsala Birth Cohort (men and women born 1915-1929) between 1964 and 2002. Data on circumstances at birth retrieved from archived obstetric records; data on social characteristics in adulthood, hospitalizations, and date of death obtained through linkage to Censuses, Hospital Discharge Register, and Cause of Death Register. We found a U-shaped association between standardized birth weight and case fatality of AMI in men (p = 0.045 for age and period adjusted quadratic trend over quintiles of standardized birth weight) that was driven by cases of AMI occurring during the early years of follow-up. We found no association between standardized birth weight and case fatality of AMI in women. There was a statistically non-significant inverse association of AMI case fatality with social class at birth as well as with social class and household income in adulthood in the cohort. Marital status was a strong determinant of case fatality in men. Standardized birth weight for gestational age was associated with case fatality of AMI in men. Social class at birth was weakly inversely associated with case fatality of AMI in the cohort.

Long-Term Trends in Myocardial Infarction Incidence and Case Fatality in the National Heart, Lung, and Blood Institute’s Framingham Heart Study

Whereas the prevalence of coronary heart disease risk factors has declined over the past decades in the United States, acute myocardial infarction (AMI) rates have been steady. We hypothesized that this paradox is due partly to the advent of increasingly sensitive biomarkers for AMI diagnosis. In Framingham Heart Study participants over 4 decades, we compared the incidence and survival rates of initial AMI diagnosis by ECG (AMI-ECG) regardless of biomarkers with those based exclusively on infarction biomarkers (AMI-marker). We used Poisson regression to calculate annual incidence rates of first AMI over 4 decades (1960 to 1969, 1970 to 1979, 1980 to 1989, and 1990 to 1999) and compared rates of AMI-ECG with rates of AMI-marker. Cox proportional-hazards analysis was used to compare AMI case fatality over 4 decades. In 9824 persons (54% women; follow-up, 212 539 person-years; age, 40 to 89 years), 941 AMIs occurred, including 639 AMI-ECG and 302 AMI-marker events. From 1960 to 1999, rates of AMI-ECG declined by approximately 50% and rates of AMI-marker increased approximately 2-fold. Crude 30-day, 1-year, and 5-year case fatality rates in 1960 to 1969 and 1990 to 1999 were 0.20 and 0.14, 0.24 and 0.21, and 0.45 and 0.41, respectively. Age- and sex-adjusted 30-day, 1-year, and 5-year AMI case fatality declined by 60% in 1960 to 1999 (P for trend <0.001), with parallel declines noted after AMI-ECG and AMI-marker. Over the past 40 years, rates of AMI-ECG have declined by 50%, whereas rates of AMI-marker have doubled. Our findings offer an explanation for the apparently steady national AMI rates in the face of improvements in primary prevention.

Temporal variation in case fatality of acute myocardial infarction in Finland

Background. Previous studies have suggested that seasonal variation and weather conditions have an influence on the incidence and mortality of acute myocardial infarction (AMI). The influence of these factors on AMI case fatality is less studied.Aims. The aim of this study was to examine the temporal variation of AMI case fatality and the effect of daily weather conditions on it.Methods. We analysed death registry and hospital discharge data from all men and women (n=7328) with their first AMI occurrence in the seven largest cities in Finland in the years 1983, 1988, and 1993, aged 25 to 74 years.Results. The mean annual 28-day case fatality was 44%. We found significant weekly and monthly variation of case fatality (P<0.001). The December holiday season had the highest case fatality throughout the year in women and men aged 65–74 years (P<0.05). The highest weekly case fatality was on Sundays; it differed significantly from the rest of the weekdays only for the oldest age-group (64–74) (P<0.01).Conclusions. There is significant weekly and monthly variation in case fatality of AMI. The highest case fatality risk for AMI is during the Christmas season and on Sundays. Weather conditions were not found to have an effect on the case fatality.

Incidence, admission and case-fatality of acute myocardial infarction: weekend versus weekday in a Japanese population: 16-year results from Takashima AMI Registry (1988–2003)

For acute myocardial infarction (AMI), "weekend" has been associated with higher incidence, admission, and fatality. But, very few studies in this regard are available in Japan. Day of the week variation in AMI was examined using an entire community covering 16-year AMI registration data from Japan. Data were obtained from the Takashima AMI Registry, which covers a stable population of approximately 55,000 in central Japan. There were 379 registered first ever AMI cases with 121 fatal events within 28 days of onset during 1988-2003. We divided the days into two groups: 'Weekend' (Saturday and Sunday) and 'Weekdays' (Monday to Friday). The incidence rate (per 100,000 person-year), admission rate (per 1,000 days) and 28-day case-fatality rates (per 100 events) as well as corresponding rate ratios were calculated with 95% confidence intervals. The distribution of the day of the week for onset, admission and fatality for all subjects was fairly random in our study population; incidence (chi (2) test, P = 0.8), admission (chi (2) test, P = 0.9) and case-fatality (chi (2) test, P = 0.8). The incidence, admission, and case-fatality rates were similar for the 2 day-groups. The incidence rate ratio 1.06 (95% CI: 0.9-1.3), admission ratio 1.03 (95% CI: 0.8-1.3), and case-fatality ratio 1.18 (95% CI: 0.7-1.9) showed no significant risk difference between weekend and weekday. After various adjustments, hazard ratio for weekend AMI in reference to weekday AMI was 1.07 (95% CI: 0.5-2.1). There were no obvious differences in occurrence, hospital admission and acute outcome for AMI patients in the weekday or weekend.

Seasonal Pattern of Incidence and Case Fatality of Acute Myocardial Infarction in a Japanese Population (from the Takashima AMI Registry, 1988 to 2003)

We examined the seasonal variations in the incidence and case fatality of acute myocardial infarction (AMI) in a geographically defined population using 16-year AMI registration data. It remains unclear whether the incident events of AMI display any seasonal variation. Documentation of such a pattern may foster investigation for understanding the potential mechanisms responsible for these effects and may provide novel avenues for prevention of AMI. Data were obtained from the Takashima AMI Registry, which covers an entire community of approximately 55,000 in central Japan. There were 335 definite cases of AMI during 1988 to 2003 (217 men, 118 women). Of these, there were 96 fatal cases (53 men, 43 women) within 28 days of onset. Incidence rates (per 100,000 person-years) and case fatality rates with 95% confidence intervals (CI) were calculated across seasons. Poisson regression analysis was used to calculate the incidence rate, and case fatality ratios adjusted for age and gender. The AMI incidence rate was higher in winter (44.9, 95% CI 35.9 to 53.9) and spring (44.1, 95% CI 35.3 to 52.9) than the other seasons. After adjustment for age and gender, AMI risk was 1.4 (95% CI 1.03 to 1.9) times higher in winter and was 1.4 (95% CI 1.01 to 1.9) times higher in spring than summer. The 28-day AMI case fatality rate was also higher in winter (34.4%, 95% CI 24.9 to 43.9) and spring (32.3%, 95% CI 22.9 to 41.7). Age- and gender-adjusted fatality risk was 2.4 (95% CI 1.2 to 4.9) times higher in winter and 2.3 (95% CI 1.1 to 4.6) times higher in spring than summer. In conclusion, higher AMI incidence and case fatality rates were observed in winter and spring in a Japanese population.

Quantifying the effect of age on short-term and long-term case fatality in 14000 patients with incident cases of cardiovascular disease

Age is a major determinant of case fatality following acute cardiovascular disease (CVD) events. Its impact, however, varies by time after the event, sex and diagnostic category. We were able to quantify these effects with good precision in a large cohort of patients. A national cohort of 14,227 CVD patients representing all the recorded first-CVD events in people aged 35-84 years in New Zealand in 1995 were examined, using electronic linkage of routine health data. Case fatality by age was assessed in three phases: prehospital deaths, fatality after hospitalization up to 28 days and from 28 days up to 5 years after the event. It was assessed in these phases by sex and by the diagnostic categories: acute myocardial infarction (AMI), stroke and other coronary heart diseases. Case fatality in the prehospital phase showed substantial age differences. In particular, a strong positive monotonic age gradient was observed for AMI, but a U-shaped age-case-fatality gradient for stroke. From admission to 28 days, AMI case fatality demonstrated the strongest age gradient. In contrast, there was minimal age effect on 28-day stroke mortality, and case fatality for other coronary heart diseases was low. From 28 days to 5 years, there was a substantial positive monotonic age by case-fatality gradient for all diagnoses. Age has a large impact on case fatality following cardiovascular events, although the effect varies significantly by time elapsed after the event, diagnostic category and sex. As the lifetime benefits of many cardiovascular interventions depend on preintervention risk and case fatality, the role of age needs careful attention while making treatment decisions.

Analysis With the Propensity Score of the Association Between Likelihood of Treatment and Event of Interest in Observational Studies. An Example With Myocardial Reperfusion

Analysis of the effect of treatment in observational studies is complex due to differences between treated and nontreated patients. Calculating the probability of receiving treatment conditioned on relevant covariates (propensity score [PS]) has been proposed as a method to control for these differences. We report an application of PS to assess the association between reperfusion treatment and 28-day case fatality in patients with acute myocardial infarction (AMI). We describe the procedure used to calculate PS for receiving reperfusion treatment, and different strategies to analyze the association between PS and case fatality with regression modeling and matching. Data were from a population-based registry of 6307 patients with AMI in Spain during 1997-98. The PS for reperfusion was calculated in 5622 patients. In the multivariate analysis, reperfusion was associated with lower case fatality (OR = 0.59; 95% confidence interval [95% CI]: 0.46-0.77). When PS was included as a covariate, this association became non- significant (OR = 0.76; 95% CI: 0.57-1.01). In the subgroup of matched patients with a similar PS (n = 3138), treatment was not associated with case fatality (OR = 0.95; 95% CI: 0.72-1.26). When the influence of cases with missing data on PS was controlled for, reperfusion treatment was associated with lower fatality (OR = 0.66; 95% CI: 0.55-0.80). Calculating propensity score is a method that controls for differences between treated and nontreated patients. This score has limitations when matching is incomplete and when data are missing. Results of the present example suggest that reperfusion treatment reduces AMI case fatality.