Sex differences in survival after myocardial infarction in Sweden; data from the Swedish National Acute Myocardial Infarction Register.

AIMS: Women, particularly younger women, hospitalized with acute myocardial infarction have been found to have poorer prognosis than men. A large proportion of deaths due to myocardial infarction, however, occur in the pre-hospital phase. We set out to analyse age-specific sex differences in survival after myocardial infarction at different time intervals from the onset of acute myocardial infarction, including pre-hospital deaths and 1-year overall survival. METHODS AND RESULTS: The National Acute Myocardial Infarction Register in Sweden was used to analyse age-specific sex differences in mortality outside hospital, 28-day mortality and 1-year mortality in 353 905 cases occurring between 1987 and 1995 in Swedish men and women aged 30 to 89 years. Overall, one in four of all myocardial infarction victims died outside hospital. At all ages, except in individuals younger than 50 years, men had higher pre-hospital mortality. The odds of dying within 28 days for women below 50 years of age, compared to men, was 1.84 (1.56--2.18) in hospitalized patients and 1.31 (1.18--1.46) in all infarction patients. Above the age of 65, in the total population with myocardial infarction, women had a better prognosis, with odds ratios ranging from 0.83 to 0.89. In patients surviving the first 28 days, 4.0% of the women and 2.9% of the men below the age of 50 were dead within a year after the infarction, odds ratio 1.37 (1.06--1.76). This excess mortality was mainly due to diabetes and non-cardiac causes. Only women younger than 50 years had a significantly poorer overall 1-year survival than men of the same age. At the age of 70 or more, women had a small survival advantage. CONCLUSION: In the total acute myocardial infarction population, only women under 50 years of age have a consistently worse prognosis than men. Much of the excess mortality in young women seems to be associated with diabetes.

A national record linkage to study acute myocardial infarction incidence and case fatality in Sweden.

BACKGROUND: During the last decades substantial temporal changes, as well as population differences, in coronary heart disease mortality have occurred in Sweden. There is little information to what extent these changes and differences also apply to myocardial infarction incidence. The aim of this paper was to describe the methods used to identify cases in a recently developed National Acute Myocardial Infarction Register in Sweden, and to present estimates of incidence and case fatality in Sweden. MATERIAL AND METHODS: Incident cases of acute myocardial infarction (AMI) were identified by record linkage of routinely collected data on hospital discharges and deaths. Case fatality within 28 days was ascertained by linkage of incident cases to the National Cause of Death Register. RESULTS: About 40 000 new cases of AMI per year were recorded in Sweden during 1987-1995. Well-known differences in incidence with regard to age and gender were observed, as well as a decline in incidence between 1987 and 1995. A similar case fatality was seen in men and women aged 30-89 among hospitalized cases. When fatal cases outside hospital were also considered the case fatality was somewhat higher in men. Examination of medical records for a national sample of ischaemic heart disease patients suggested a high sensitivity (94%) and a high positive predictive value (86%) for ICD-9 code 410 in hospital discharge data with regard to definite AMI. CONCLUSIONS: The National Acute Myocardial Infarction Register offers a new possibility to study the incidence of AMI, as well as case fatality, in Sweden.

Attack rate, mortality and case fatality for acute myocardial infarction in Sweden during 1987-95. Results from the national AMI register in Sweden.

OBJECTIVE: To assess trends in attack rate, mortality and case-fatality of acute myocardial infarction (AMI) in Sweden. SETTING: All 303 324 Swedes discharged from hospitals, or deceased, with a diagnosis of AMI between 1987 and 1995. DESIGN: Analysis based on the National AMI Register in Sweden. The National AMI Register was assembled by linking the records of the National Hospital Discharge Register and the National Cause of Death Register in Sweden. MAIN OUTCOME MEASURES: Age-standardized attack rate, mortality and case fatality rates for AMI. RESULTS: Between 1987 and 1995, the age-standardized attack rate of AMI declined by 11% for men and 10% for women, whilst mortality from AMI decreased by 14% for both sexes. The decrease was most pronounced for men below the age of 64, with a reduction of 22% in attack rate and nearly 30% in mortality. There was no change over time in the case fatality rates on the date of attack, including also deaths outside hospital, whilst case fatality within 28 days decreased from 49 to 45% amongst men, and 45 to 42% amongst women. This reduction persisted over 1 year of follow-up. CONCLUSIONS: The decrease in attack rate of AMI in Sweden may be attributed both to changes in risk factors amongst the population and to improved medical intervention. The decline in case fatality rates indicates that improved treatment of patients with AMI has contributed to the reduction in mortality. However, the high, and essentially unchanged, proportion of deaths outside hospital stresses the importance of disease prevention.

Type of occupation and near-future hospitalization for myocardial infarction and some other diagnoses.

Using three different registers a cohort study was undertaken to describe the relationship between type of occupation and hospitalization. A total of 958 096 subjects aged 20-64 years were followed-up for one year regarding inpatient care. Several significant associations between type of occupation and incidence of hospitalization for different diagnoses were observed. Male subjects employed in occupations where a high proportion reported a combination of hectic work and few possibilities to learn new things were more frequently hospitalized for myocardial infarction than other working men. The relative 'hospitalization' ratio for men 20-54 years of age in these strenuous occupations was estimated as 1.6 with a 95% confidence interval of 1.3-1.9. For women, the relative 'hospitalization' ratio in the ages 20-64 in occupations where a high proportion reported a combination of hectic and monotonous work was estimated as 1.6 with a 95% confidence interval of 1.1-2.3. Both these associations were statistically significant even after controlling for 12 possible confounding factors.