Esko Kaarsalo

Relationship of Socioeconomic Status to the Incidence and Prehospital, 28-Day, and 1-Year Mortality Rates of Acute Coronary Events in the FINMONICA Myocardial Infarction Register Study

BACKGROUND Low socioeconomic status (SES) is associated with increased coronary heart disease mortality rates. There are, however, very little data on the relation of SES to the incidence, recurrence, and prognosis of myocardial infarction (MI) events. METHODS AND RESULTS The FINMONICA MI Register recorded detailed information on all MI events among men and women aged 35 to 64 years in 3 areas of Finland during the period of 1983 to 1992. We carried out a record linkage of the MI register data with files of Statistics Finland to obtain information on indicators of SES, such as taxable income and education, for each individual who is registered. In the analyses, income was grouped into 3 categories (low, middle, and high), and education was grouped into 2 categories (basic and secondary or higher). Among men with their first MI event (n=6485), the adjusted incidence rate ratios were 1.67 (95% CI 1.57 to 1.78) and 1.84 (95% CI 1.73 to 1.95) in the low- and middle-income categories compared with the high-income category. For 28-day mortality rates, the corresponding rate ratios were 3.18 (95% CI 2.82 to 3.58) and 2.33 (95% CI 2.03 to 2.68). Significant differentials were observed for prehospital mortality rates, and they remained similar up to 1 year after the MI. Findings among the women were consistent with those among the men. CONCLUSIONS The excess coronary heart disease mortality and morbidity rates among persons with low SES are considerable in Finland. To bring the mortality rates of low- and middle-SES groups down to the level of that of the high-SES group constitutes a major public health challenge.

Epidemiology of subarachnoid hemorrhage in Finland from 1983 to 1985.

The age-standardized incidence of subarachnoid hemorrhage was 33/100,000/yr among Finnish men and 25/100,000/yr among Finnish women. Subarachnoid hemorrhage represented 11% of all strokes detected during 1983-1985 in the community-based stroke register in three areas of Finland. Age-standardized mortality from subarachnoid hemorrhage was 18/100,000/yr among men and 12/100,000/yr among women aged 25-74 years, representing in men 22% and in women 23% of all deaths from stroke in the register. The case-fatality rate of subarachnoid hemorrhage was high: 35% among men and 33% among women within 2 days after the onset of the stroke attack and 48% in men and 46% in women at 1 month. Our findings suggest that the incidence and mortality of subarachnoid hemorrhage in Finland are among the highest worldwide, although differences in criteria, study methods, and classification procedures reduce the comparability of studies from different countries. The occurrence of subarachnoid hemorrhage in our present study is also higher than that previously reported in this country. We believe that this is more likely due to changes in diagnostic classification and improvements in detection of the disease than to a real increase in the morbidity and mortality of subarachnoid hemorrhage.

Seasonal Variation in the Occurrence of Stroke in a Finnish Adult Population: The FINMONICA Stroke Register

BACKGROUND AND PURPOSE Seasonal influence on the incidence of and mortality from cerebrovascular disease has been reported during the last three decades, but generally with some discrepancy in results, particularly regarding stroke subtypes. The aim of this study was to examine seasonal variation in the incidence, mortality, and case-fatality rate of stroke in data from the FINMONICA population-based stroke register. METHODS During 1982 to 1992, 15449 stroke events were registered in the monitored populations aged 25 to 99 years in three geographic areas of Finland: the provinces of Kuopio and North Karelia in eastern Finland and the Turku/Loimaa area in southwestern Finland. We analyzed the seasonal and monthly incidence, mortality, and case-fatality rate of stroke and subtypes of stroke by pooling the data for the three areas and stratifying by sex and age. RESULTS The rate of occurrence of ischemic stroke events was 12% (95% confidence interval [CI], 5% to 20%) greater in men and 11% (95% CI, 4% to 19%) greater in women in winter than in summer. For intracerebral hemorrhage, we observed a 28% (95% CI, 3% to 58%) greater rate of occurrence in men and a 33% (95% CI, 6% to 66%) greater rate of occurrence in women in winter than in summer. The occurrence of subarachnoid hemorrhage did not vary significantly by season. The greater incidence of ischemic strokes in winter was particularly prominent among men aged 25 to 64 years and less prominent in elderly men and in women. The 28-day case-fatality rate of ischemic stroke showed significant seasonal variation only in women (P = .001), with the lowest rate in summer. CONCLUSIONS There is a significantly greater incidence of ischemic strokes and intracerebral hemorrhages during winter in Finland. Further research that also takes meteorologic and sociodemographic factors into account is warranted, since it may help to determine new ways to prevent strokes.

Socioeconomic Status and Ischemic Stroke The FINMONICA Stroke Register

Background and Purpose— It has been shown that low socioeconomic status is associated with death from stroke. More-detailed data have, however, remained scanty. The purpose of the present study was to examine the association of socioeconomic status with ischemic stroke. Besides mortality, we analyzed the incidence, case-fatality ratio, and prognosis of ischemic stroke events. Methods— Our population-based study included 6903 first stroke events registered by the FINMONICA Stroke Register in 3 areas of Finland during 1983 to 1992. Indicators of socioeconomic status, such as taxable income and education, were obtained by record linkage of the stroke register data with files of Statistics Finland. Results— Incidence, case-fatality ratio, and mortality rates for ischemic stroke were all inversely related to income. Furthermore, 28 days after the onset of symptoms, a greater proportion of patients with low income than of those with high income was still in institutionalized care and/or in need of help for their activities of daily living. Population-attributable risk of the incidence of first ischemic stroke due to low socioeconomic status was 36% for both sexes. For the death from first ischemic stroke, it was 56% for both sexes. Conclusions— Persons with low socioeconomic status have considerable excess rates of morbidity and mortality from ischemic stroke in Finland. A reduction in this excess could markedly decrease the burden of ischemic stroke to the society and thus constitute an important public health improvement.

Atrial Fibrillation and Stroke Mortality and Causes of Death After the First Acute Ischemic Stroke

BACKGROUND AND PURPOSE Atrial fibrillation (AF) is a risk factor for stroke. This study was undertaken to determine the influence of AF on the mortality of stroke patients and on the causes of death after a stroke event. METHODS Patients with first ischemic stroke who were .35 to 74 years old and registered in the FINMONICA stroke register during 1982 through 1992 were analyzed (n = 6912). There were 642 patients with AF (9.3%) (mean age, 67 years) and 6270 patients without AF (90.3%) (mean age, 63 years). The association between AF and stroke mortality was investigated by use of logistic regression and Cox proportional hazards models. RESULTS Mortality was higher in the AF group both at 28 days (19.5% versus 14.4%, P < .001) and 1 year after the attack (30.5% versus 21.8%, P < .001). After adjustment for age and sex, the odds ratio for 28-day case fatality (AF versus non-AF) was 1.27 (95% CI, 1.03 to 1.56; P = .003), and that for 1-year mortality was 1.36 (95% CI, 1.14 to 1.63; P < .001). In the proportional hazards model, AF was a significant independent risk factor for 1-year mortality (hazard ratio, 1.26; 95% CI, 1.09 to 1.46; P = .002). Cardiac causes of death were more common in the AF group at the acute stage. In the course of 1 year, there were no differences in the distributions of causes of death. CONCLUSIONS Stroke patients with AF are at high risk of death both at the acute phase of stroke and during the subsequent year after the first acute stroke event. Mortality from cardiac diseases prevailed in the AF group during the acute phase of stroke. Careful cardiac evaluation and treatment are essential in patients with AF and stroke.

The validity of hospital discharge register data on coronary heart disease in Finland

We studied the validity of the Finnish hospital discharge register data on coronary heart disease (CHD) for the purposes of epidemiologic studies and health services research. The Finnish nationwide hospital discharge register (HDR) was linked with the FINMONICA acute myocardial infarction (AMI) register for the years 1983–1990. The frequency of errors in the HDR was assessed separately. Between 8% and 13% of hospitalized AMI events registered in the AMI Register were not found in the HDR with an ICD code for CHD. Problems with the register linkage and the use of some ICD code other than one of the codes for CHD explained these missing events. The frequency of errors in the personal identification number was about 5% in the early 1980s. After 1986 errors were found only occasionally. The diagnosis recorded in the HDR was the same as that in the discharge sheet in about 95% of hospitalizations. The positive predictive value of the ICD code 410 (AMI), compared with the FINMONICA definite+possible AMI category, was very high and stable, about 90% in all areas and all hospitals, but it sensitivity varied from 50% at local hospitals to 80% at central hospitals. In summary, data on CHD obtained from the Finnish hospital discharge register give, on average, a correct picture on changes in the occurrence of AMI in Finland and can, with necessary caution, be used in epidemiological studies and health services research. However, the classification of individual cases is not standardized in the HDR, but varies over time, between geographical areas and the levels of care. Therefore, these data should not be used without confirmation in studies where correct classification of individual outcomes is of crucial importance, such as follow-up studies and case-control studies.

Ten-Year Trends in Stroke Incidence and Mortality in the FINMONICA Stroke Study

BACKGROUND AND PURPOSE The trends in stroke incidence reported so far have not been entirely consistent, although declining trends in mortality from stroke have been reported from a number of studies around the world. This study aims to evaluate the 10-year trends (from 1983 through 1992) in incidence, attack rate, and mortality of stroke in the Finnish population. METHODS A population-based stroke register was set up in the early 1980s to collect data on all suspected events of acute stroke that occurred in the population aged 25 to 74 years permanently residing in three geographic areas of Finland: the provinces of Kuopio and North Karelia in eastern Finland and the Turku-Loimaa area in southwestern Finland. Trends in age-standardized attack rates, incidence, and mortality were calculated for the period studied. RESULTS During the 10-year study period, 11 392 acute stroke events occurred in the monitored populations. A statistically significant decline was observed in the pooled FINMONICA data, both in the incidence of stroke (-1.7% with 95% confidence interval [CI], -3.0% to -0.5% per year in men; -2.2% with 95% CI, -3.6% to -0.7% per year in women) and in mortality from stroke (-5.2% with 95% CI, -8.2% to -2.2% per year; -4.7% with 95% CI, -8.2% to -1.2% per year). The attack rate of stroke also declined significantly in both sexes. When the areas were considered separately, the declining trends were observed within each area. The decline in incidence of stroke was, however, statistically significant only among men and women in Kuopio and among women in Turku/Loimaa. Mortality declined significantly in all three areas among men but among women only in Kuopio. The incidence to mortality rate ratio increased during the study period, indicating a steeper fall in mortality than in incidence. CONCLUSIONS A substantial decline in both stroke incidence and mortality was observed in the adult and elderly population in the FINMONICA study areas. Part but not all of the decline in stroke mortality, observed also in the official mortality statistics, can be attributed to the decline in stroke incidence during this 10-year period.

The Validity of the Routine Mortality Statistics on Coronary Heart Disease in Finland: Comparison with the FINMONICA MI Register Data for the Years 1983–1992

We compared the diagnoses obtained from the routine mortality statistics with the standardized World Health Organization (WHO) MONICA (multinational MONItoring of trends and determinants in CArdiovascular disease) classification in suspect coronary heart disease (CHD) deaths registered in the FINMONICA myocardial infarction (MI) register during 1983-1992. All CHD deaths from routine mortality statistics (International Classification of Diseases codes 410-414) were registered in the MI register. Of the CHD deaths in routine mortality statistics 1.7% in men and 4.8% in women did not fulfill the MONICA criteria for CHD death (P<0.001 for the difference between the sexes). In men 4.7% and in women 7.3% (P=0.004) of the deaths registered in the MI Register and classified as CHD deaths by MONICA criteria had another underlying cause of death than CHD in routine mortality statistics; this proportion increased over time in both sexes (P=0.002 in men and P=0.77 in women). The CHD mortality trends obtained separately from the routine mortality statistics and from the FINMONICA MI Register were very similar. In conclusion, the high CHD mortality in Finland reported by the routine mortality statistics is real. It is possible that some CHD deaths have escaped registration, but the decline seen in the CHD mortality is also real.

Trends in Case-Fatality of Stroke in Finland During 1983 to 1992

BACKGROUND AND PURPOSE Stroke mortality has been declining in Finland during the past 20 years. It is not known, however, whether this favorable development is attributable to the decline in the incidence or case-fatality of stroke. For this reason we examined the trends in case-fatality of stroke, including trends by subtype of stroke. METHODS The analyses were carried out using data of the community-based FINMONICA Stroke Register, which was operating in three geographic areas of Finland during 1983 to 1992. All stroke events (n = 11,171) in persons aged 35 to 74 years were included in this register. RESULTS The 28-day case-fatality of stroke fell yearly by 3.6% (P = .01) in men and by 2.6% (P = .2) in women. At the end of the study period, the average 28-day case-fatality of all strokes was 20% in men and 21% in women. Considerable differences by subtype of stroke were observed. The 28-day case-fatalities at the end of the study period were in men-56% for subarachnoid hemorrhage, 42% for intracerebral hemorrhage, and 14% for cerebral infarction. In women, the corresponding figures were 49%, 49%, and 14%. The 28-day case-fatality of subarachnoid hemorrhage did not change during the study period, but for intracerebral hemorrhage, a significant decline was observed in men and there was a declining trend also in women. The 28-day case-fatality of cerebral infarction declined significantly in both genders. CONCLUSIONS With the exception of subarachnoid hemorrhage, the 28-day case-fatality of stroke has fallen in Finland. It is likely that this fall has contributed to the decline in stroke mortality.

Declining trends in incidence, case-fatality and mortality of stroke in three geographic areas of Finland during 1983-1989. Results from the FINMONICA stroke register.

Stroke mortality has decreased during the last decade in many industrialized countries, but there has been no clear evidence for a decline in the incidence of stroke. The present study analyzes the trends in the incidence, mortality and case-fatality of stroke in Finland from 1983 to 1989. We used data from the FINMONICA stroke register, a community based register collecting information on all suspected stroke cases aged 25-74 in three geographical areas of Finland. Annual attack rate, incidence, mortality and case-fatality rates were calculated for all strokes and for different subcategories of stroke. A linear regression model was applied to calculate the yearly trends of these rates. In men, the attack rate of stroke was 336/100,000 in 1983 and 310/100,000 in 1989 (-8% during the observation period); incidence declined from 269/100,000 in 1983 to 236/100,000 in 1989 (-12%); mortality declined from 82/100,000 to 64/100,000 (-22%), and case-fatality declined from 25% to 21% (-18%). Also among women similar declining trends were observed (-11%, -13%, -16%, and -10% respectively), but they were not statistically significant. In both incidence and mortality of stroke, the decline was seen in all age groups. Incidence and mortality of cerebral infarction declined similarly to all strokes. A large fall in the incidence (-24% in both men and women) and mortality (-38% in men and -27% in women) of subarachnoid haemorrhage was also observed. An increasing trend, although not significant, was instead observed for cerebral haemorrhage. First stroke and especially first cerebral infarction contributed most to the decline in case-fatality. The availability of computerized brain tomography improved from 18% in 1983 to 60% in 1989. We observed a fall in the incidence, mortality, and case-fatality of stroke during 1983-1989. Among the subtypes of stroke, cerebral infarction contributed most to the decline, but the data suggested also a declining trend in the incidence and mortality of subarachnoid haemorrhage, observed now for the first time in Finland since the 1960s. The fall in the incidence of stroke was not as steep during the 1980s as it was during the 1970s; Finland is anyhow the only European country which has reported a decreasing trend in stroke incidence during the 1980s. We need now to investigate how much the decline in the classical risk factors for stroke observed in Finland during the last two decades predicts the observed trends.