Migraine patients have lower systolic but higher diastolic blood pressure compared with controls in a population-based study of 21,537 subjects. The Reykjavik Study.

Several studies have explored a possible association between migraine and hypertension, with contradictory results. Because of this uncertainty the relation between blood pressure (BP) and migraine was studied in 10,366 men and 11,171 women in a population-based longitudinal study. A modified version of the 1988 International Headache Society criteria was used for diagnosis of migraine. Logistic regression analysis was used. The crude 1-year prevalence of migraine was 5.2% among men and 14.1% among women. No significant association was found between hypertension and migraine. For a one standard deviation (SD) increase in diastolic BP the probability of having migraine increased 14% (P = 0.11) for men and 30% (P < 0.0001) for women. For a 1-SD increase in systolic BP the probability of having migraine decreased 19% (P = 0.007) for men and 25% (P < 0.0001) for women. It was also found that for a 1-SD increase in pulse pressure the probability of having migraine decreased 13% (P = 0.005) for men and 14% (P < 0.0001) for women. In a population-based study of men and women it was found that subjects with migraine had lower pulse pressure, lower systolic BP and higher diastolic BP compared with controls.

Risk profiles and prognosis of treated and untreated hypertensive men and women in a population-based longitudinal study: the Reykjavik Study.

The aim was to examine the risk profiles and prognosis of treated and untreated hypertensive subjects and examine to what degree confounding by indication was present in a population-based cohort study with up to 30-year follow-up. The study population consisted of 9328 men and 10 062 women, aged 33-87 years at the time of attendance from 1967 to 1996. The main outcome measures were myocardial infarction (MI), cardiovascular disease (CVD) mortality and all-cause mortality. Comparing the risk profiles between treated and untreated subjects entering the study showed significantly higher values for some risk factors for treated subjects. During the first 10 years, hypertensive men without treatment, compared with those treated, had a significantly lower risk of suffering MI, CVD and all-cause mortality, hazard ratio (HR) 0.72 (95% CI; 0.57, 0.90), 0.75 (95% CI; 0.59, 0.95) and 0.81 (95% CI; 0.61, 0.98), respectively. No significant differences in outcome were seen during the following 20 years. In identically defined groups of women, no significant differences in mortality were seen between groups. Subgroup analysis, at two stages of the study 5 years apart, revealed that some cardiovascular risk factors had a higher prevalence in hypertensive men who were treated at the later stage, compared with those who remained untreated (P=0.004). In conclusion, hypertensive treated men had a worse prognosis during the first 10 years of follow-up than untreated ones, which is most likely due to worse baseline risk profile. Hypertensive men that were treated at a later stage had a worse risk profile than those not treated at a later stage.

Survival and trends of occurrence of left ventricular hypertrophy, gender differences, 1967-92: The Reykjavik Study.

OBJECTIVE: We estimated the prevalence, incidence and risk factors of left ventricular hypertrophy (LVH) in a prospective cohort study of 26 489 participants. MATERIAL AND METHODS: The LVH was defined as Minnesota Code 310 on electrocardiogram (ECG). Everyone with this code at first visit was defined as a prevalence case and those who developed it between subsequent visits were incidence cases. The comparison cohort were all other participants in the Reykjavik Study stages I-V. RESULTS: A total of 297 men and 49 women were found to have LVH of 3.2% and 0.5%, respectively. The incidence was 25 per 1000 per year amongst men and six per 1000 per year amongst women. Prevalence in both genders increased with increasing age. Risk factors at the time of diagnosis were systolic blood pressure [odds ratio (OR) per mmHg 1.02; 95% confidence interval (CI): 1.01-1.03], age (OR per year 1.04; 95% CI: 1.02-1.05), silent myocardial infarction (MI) (OR 3.18; 95% CI: 1.39-7.27) and ST-T changes (OR 3.06; 95% CI: 2.14-4.38) amongst men and systolic blood pressure and age for women with similar odds ratio. Predictive factors for acquiring LVH were systolic blood pressure [incidence ratio (IR) 1.01; 95% CI: 1.01-1.02] and angina with ECG changes (IR 2.33; 95% CI: 1.08-5.02) amongst men and systolic blood pressure amongst women (IR 1.03; 95% CI: 1.01-1.04). The risk for coronary mortality was significantly increased amongst women with hypertrophy [hazard ratio (HR) 3.07; 95% CI: 1.5-6.31] and their total survival was poorer with increasing time from diagnosis of LVH (HR 2.17; 95% CI: 1.36-3.48). CONCLUSIONS: We conclude that the presence of LVH and its appearance is associated with age and increased blood pressure amongst both genders. Women with LVH have poorer survival than other women and they are at threefold risk of dying of ischaemic heart disease.

The relationship between educational level and mortality. The Reykjavík Study.

OBJECTIVE: Epidemiological studies have indicated an association between socioeconomic factors and health. It has not been clearly established whether this association is wholly or partly independent of classical risk factors. Our objective was to estimate the relationship between educational level and coronary artery disease (CAD), mortality and all-cause mortality. The Reykjavík Study involving 18 912 participants followed-up 4-30 years provides an ideal opportunity to address this question. DESIGN AND SUBJECTS: The participants were aged 33-81 years and living in the Reykjavík area. They were divided into four groups according to education. The standard risk factors were assessed on entry and mortality, and cause of death registered during follow-up. Multiple Cox regression analysis was applied to assess the relationship between age at examination, year of examination, educational level and mortality. RESULTS: The all-cause mortality and CAD mortality was significantly related to education, even after adjustment for classical risk factors. For men, 14% (95% CI: 2-24) reduction was found in CAD mortality for those having high school education relative to elementary school. The figures for junior college and university education were 17% (95% CI: 1-31) and 38% (95% CI: 21-32), respectively. These figures were only slightly lower when major CAD risk factors were controlled for and still significant. Similar figures were found for all-cause mortality. For women 34% (95% CI: 18-48) reduction was found in CAD mortality for high school education and 55% (95% CI: 22-74) for junior college, but too few had university education for reliable results. The figures were lower for all-cause mortality, but significant. The figures were reduced when major CAD risk factors were controlled for, but still significant. CONCLUSION: Education is a strong protective factor both for all-cause and CAD mortality. Only a small part of this effect can be explained through conventional risk factors.

Helicobacter pylori antibodies and gastric cancer in Iceland - The decline in IgG antibody level is a risk factor.

H. pylori infection is considered a causal agent of duodenal ulcer and a significant risk factor for gastric cancer. Retrospective cohort studies have demonstrated a significant association between presence of antibody to H. pylori and gastric cancer when using samples obtained years before the diagnosis but not at the time of diagnosis. The present study investigates, in a population-based cohort, whether a decline occurs in H. pylori antibody levels before the diagnosis of stomach cancer. Repeat samples (2 to 5) were available from 23 persons with gastric cancer taken up to 20 years before the diagnosis and 128 control subjects matched for gender, age, time and number of repeat samples. The odds ratio of developing stomach cancer was 1.16 (95% CI 1.05-1.28) for those showing decline in antibody levels of 1 relative antibody activity unit per year versus those with constant or rising levels. We conclude that this decline in antibody levels in cases, and not in controls, supports an active role of H. pylori in the pathogenesis of gastric cancer by causing atrophic gastritis, and provides a better risk assessment for gastric cancer compared to single measurements.

[Changes in myocardial infarction incidence and mortality in Iceland.].

INTRODUCTION: According to public health reports ischaemic heart disease was an uncommon cause of death in Iceland at the beginning of the last century. This death rate increased steadily until the ninety-eighties whereafter it leveled off and started to decline. The objective of the present study is to assess in detail the changes in myocardial infarction attack, incidence and death rate as well as case fatality. MATERIAL AND METHODS: Crude death rate from ischaemic heart disease is available from the Statistical Bureau of Iceland from 1911 to 1996 and age and sex standardized death rate from 1951. In this paper, however, the material is mainly from the MONICA Project, a multinational study of myocardial infarction under the auspices of the World Health Organization. The study, in which Iceland has participated since 1981, registers all myocardial infarctions in people aged 25-74 years in the whole country. The registration is performed according to standardized criteria and external quality control was applied throughout by WHO designated quality control centers. The registration now covers the period 1981-1998. RESULTS: The crude death rate in ischaemic heart disease in both sexes combined increased steadily until about 1980 when it accounted for about 30% of deaths. Age and sex specific death rate from these diseases increased from 1951 to about 1970, leveled off for the next 10 years and has since decreased. The MONICA data show a decline of death rate from myocardial infarction of 57% in men aged 25-74 during 1981-1998 and a 51% decline in women. Incidence rate has declined by 40% and 34% in men and women respectively and attack rate by 49% and 44%. Incidence, death rate and case fatality in myocardial infarction in Iceland compares favorably with other European countries. CONCLUSIONS: Myocardial infarction incidence and death rates have been declining in Iceland during the last two decades. Case fatality is now among the lowest compared to other countries. Preventive measures are most likely to further reduce incidence and death rates in myocardial infarction in Iceland.

Epidemiology of Dupuytren's disease: clinical, serological, and social assessment. The Reykjavik Study.

Dupuytren's disease or palmar fibromatosis is a common disabling hand disorder, mainly confined to Caucasians of northwestern European origin. The prevalence of Dupuytren's disease and possible risk factors related to the disease were evaluated in a random sample of 1297 males and 868 females, aged 46 to 74 years. Blood samples were collected and biochemical parameters were evaluated. The possible relation between the disease and clinical, social, and biochemical parameters were estimated with age-adjusted univariate logistic regression analysis. Altogether 19.2% of the males and 4.4% of the female participants had clinical signs of Dupuytren's disease. The prevalence increased with age, from 7.2% among males in the age group 45-49 years up to 39.5% in those 70-74 years old. The more severe form of the disease, finger contractures, was found in 5.0% of the men and 1.4% had required operation, while this was rarely seen among women. In men elevated fasting blood glucose (P < 0.04), low body weight, and body mass index were significantly correlated with the presence of the disease (P < 0.001). Dupuytren's disease was common among heavy smokers (P = 0.02) and those having manual labor as occupation (P = 0.018). These results show that Dupuytren's disease is common in the Icelandic population and occupation and lifestyle seem to be related to the disease.

Association between trans fatty acid intake and cardiovascular risk factors in Europe: the TRANSFAIR study.

BACKGROUND: High intakes of trans fatty acids (TFA) have been found to exert an undesirable effect on serum lipid profiles, and thus may increase the risk for cardiovascular disease. OBJECTIVES: Investigation of the association between TFA intake and serum lipids. DESIGN: Cross-sectional study in eight European countries (Finland, France, Greece, Iceland, The Netherlands, Portugal, Spain, Sweden) among 327 men and 299 women (50-65 y). Using a dietary history method, food consumption was assessed and TFA intake was calculated with recent figures on TFA levels of foods, collected in the TRANSFAIR study. RESULTS: Mean (+/-s.d.) TFA intake was 2.40+/-1.53 g/day for men and 1.98+/-1.49 g/day for women (0.87+/-0.48% and 0. 95+/-0.55% of energy, respectively), with the highest consumption in Iceland and the lowest in the Mediterranean countries. No associations were found between total TFA intake and LDL, HDL or LDL/HDL ratio after adjustment for cardiovascular risk factors. Additional adjustment for other fatty acid clusters resulted in a significant inverse trend between total TFA intake and total cholesterol (Ptrend<0.03). The most abundantly occurring TFA isomer, C18:1 t, contributed substantially to this inverse association. The TFA isomers C14:1 t9, C16:1 t9 and C22:1 t were not associated or were positively associated with LDL or total cholesterol. CONCLUSIONS: From this study we conclude that at the current European intake levels of trans fatty acids they are not associated with an unfavourable serum lipid profile. SPONSORSHIP: Unilever Research Laboratorium, the Dutch Dairy Foundation on Nutrition and Health, Cargill BV, the Institute of Food Research Norwich Laboratory, the Nutrition Branch of the Ministry of Agriculture, Fisheries and Food, the International Fishmeal and Oil Manufacturers' Association, Kraft Foods, NV Vandemoortele Coordination Center, Danone Group, McDonalds Deutschland Inc, Danish Veterinary and Food Administration, Valio Ltd, Raisio Group. European Journal of Clinical Nutrition (2000) 54, 126-135

[In search for explanatory factors in the relationship between educational level and mortality.].

OBJECTIVE: The connection between socioeconomic status and mortality is well known in Western countries. Educational level has frequently been used as a socioeconomic indicator. In a recent Icelandic prospective study, an inverse relationship between educational level and mortality was shown. The objective of the present study is to consider possible explanatory factors. MATERIAL AND METHODS: This study was a part of the Reykjavík Study. A stratified sample of 400 people was taken from one of six study groups. The sample was equally divided between the sexes and four educational levels. Mean age of the sample was 72.7 years. Participants completed a questionnaire concerning knowledge of risk factors for coronary heart disease, expected response to symptoms of cardiac infarction, social network and use of health care. Response rate was 78.5%. The relationship between answers and educational level was assessed with logistic regression. RESULTS: People with higher education were more likely to be in personal contact with nurses and doctors and receive advice concerning health and treatment from them. Participants were generally satisfied with the Icelandic health care system and seemed generally to have good access to it. A relationship with educational level was not shown. A larger proportion of those with lower education had regular communication with their general practician. CONCLUSIONS: Our results suggest that certain health care services are integrated into the social network of those with higher education. This may lower their morbidity and mortality. Other hypotheses concerning possible explanatory factors for differences in health were not supported.

[Survival and trends of ocurrence of left ventricular hypertrophy, gender differences during 1967-1992. The Reykjavík Study.].

OBJECTIVE: We estimated the prevalence and incidence of left ventricular hypertrophy (LVH) in this large prospective cohort study of almost 20,000 participants and identified risk factors in them. Predictive factors of its appearance were evaluated along with morbidity and mortality calculations. MATERIAL AND METHODS: LVH was defined as Minnesota Code 310 on ECG. Everyone with this code at first visit was defined as a prevalence case and those who developed it between subsequent visits were incidence cases. Risk factors at the time of the diagnosis of LVH were determined with logistic regression. Predictive factors for acquiring this ECG abnormality were determined by Poisson regression. The comparison cohort were all other participants in the Reykjavík Study stages I-V. RESULTS: Two hundred ninety-seven men and 49 women were found to have LVH or 3.2% and 0.5%, respectively. The incidence was 25/1000/year among men and 6/1000/ year among women. Prevalence in both genders increased with increasing age. Risk factors at the time of diagnosis were systolic blood pressure (odds ratio pr. mmHg (OR) 1.02; 95% confidence interval (CI): 1.01-1.03), age (OR pr. year: 1.04; 95% CI: 1.02-1.05), silent myocardial infarction (MI) (OR: 3.18; 95% CI: 1.39-7.27) and ST-T changes (OR: 3.06; 95% CI: 2.14-4.38) among men and systolic blood pressure and age for women with similar odds ratio. Predictive factors for acquiring LVH were systolic blood pressure (incidence ratio (IR): 1.01; 95% CI: 1.01-1.02) and angina with ECG changes (IR: 2.33; 95% CI: 1.08-5.02) among men and systolic blood pressure among women (IR: 1.03; 95% CI: 1.01-1.04). In men severe smoking seemed to have a protective effect against developing LVH (IR: 0.36; 95% CI: 0.18-0.71). The risk for coronary mortality was significantly increased among women with hypertrophy (hazard ratio (HR): 3.07; 95% CI: 1.5-6.31) and their total survival was poorer with increasing time from diagnosis of LVH (HR: 2.17; 95% CI: 1.36-3.48). CONCLUSIONS: We conclude that the presence of LVH and its appearance is associated with age and increased blood pressure among both genders. Women with LVH have poorer survival than other women and they are at threefold risk of dying of ischemic heart disease. This could indicate that criteria for detecting LVH on ECG detect both mild and severe hypertrophy among men but only the severe hypertrophy cases among women. More sensitive ECG methods may have to be used to detect mild, moderate and severe LVH among both genders in order to differentiate the severity of LVH based on the ECG diagnosis.

Prevalence of joint complaints amongst individuals with Dupuytren's disease--from the Reykjavík study.

It has been reported that Dupuytren's disease is very uncommon amongst patients with rheumatoid arthritis (RA). We investigated the prevalence of different joint complaints in a cohort of 1297 males, aged 46-74 years, participating in a prospective longitudinal health survey. Joint complaints were less frequently observed in men with Dupuytren's disease than in those who did not have any signs of this disease. When adjusted for age the Dupuytren's patients had less frequently history of morning stiffness (odds ratio (OR)=0.65; 95% confidence interval (CI)=0.44-0.98, P=0.04), joint swelling (OR=0.52; 95% CI=0.27-1.00, P=0.05), and attendance to doctors due to rheumatic disorders (OR=0.44; 95% CI=0.15-0.86, P=0.02) than those who did not have clinical signs of Dupuytren's disease. Furthermore, these associations were even stronger after adjustment for other potential confounding factors, such as smoking, lipids, diabetes, education, and occupation. The reason for a negative association between Dupuytren's disease and joint complaints is not clear but genetic and immunological factors may be important.

The prevalence and prognosis of third-degree atrioventricular conduction block: the Reykjavik study.

OBJECTIVES: The objectives of this study were to find the prevalence of third-degree atrioventricular block in representative population sample and to estimate its prognostic significance. Most earlier studies have been performed on hospital patients and some professional groups. SETTING AND SUBJECTS: In the Reykjavik Study, a prospective cardiovascular population study, 9139 men and 9773 women aged 33-79 years were examined in 1967-91. Electrocardiograms were taken and coded according to the Minnesota code. Third-degree atrioventricular block was found in 11 persons, seven male and four female, an overall prevalence of 0.04%. All of these individuals had signs of dysrhythmia on electrocardiograms taken later, and in addition some other heart disease. The heart block was temporary in seven individuals (64%); six (55%) needed a pacemaker. CONCLUSIONS: The prevalence of third-degree atrioventricular block in this general population was low. The block was temporary in the majority of subjects. All had some underlying heart disease, which may affect the prognosis more than the heart block. Fewer subjects than expected were found to need a pacemaker.

Effects of leisure-time physical activity and ventilatory function on risk for stroke in men: the Reykjavík Study.

BACKGROUND: Stroke is a major cause of illness, death, and health expenditures. Leisure-time physical activity may reduce the risk for stroke. OBJECTIVE: To examine the association of leisure-time physical activity and pulmonary function with risk for stroke. DESIGN: Prospective cohort study. SETTING: Reykjavík, Iceland. PARTICIPANTS: 4484 men 45 to 80 years of age followed for a mean (+/-SD) of 10.6 +/- 3.6 years. MEASUREMENTS: Patients underwent physical examination, blood sampling, and spirometry and completed a questionnaire about health and exercise. Computerized hospital records were used to identify strokes, and the Icelandic National Registry was used to identify deaths. RESULTS: New stroke developed in 249 men (5.6%) (hemorrhagic stroke in 44 [18%] and ischemic stroke in 205 [82%]). In a multivariable hazard analysis that controlled for known risk factors for cerebrovascular disease, leisure-time physical activity maintained after 40 years of age was associated with a reduced risk for stroke (relative risk, 0.69 [CI, 0.47 to 1.01] for total stroke and 0.62 [CI, 0.40 to 0.97] for ischemic stroke). Risk for stroke increased with diminished ventilatory function (FVC or FEV1) (relative risk, 1.9 [CI, 1.06 to 3.25] for the lowest compared with the highest quintile). CONCLUSION: Middle-aged men who participate in leisure-time physical activity and have good pulmonary function seem to have a lower risk for stroke than men who are not active or have diminished pulmonary function.

Coronary heart disease mortality amongst non-insulin-dependent diabetic subjects in Iceland: the independent effect of diabetes. The Reykjavik Study 17-year follow up.

OBJECTIVES: The main aim of this study was to estimate the independent risk for coronary heart disease (CHD) death associated with non-insulin dependent (Type 2) diabetes (NIDDM) and effect on life expectancy. DESIGN AND SETTING: The Reykjavik Study is a prospective cardiovascular population study which started in 1967. A randomized selection procedure identified individuals for invitation to participate, based on their year and date of birth. Participants were examined in the years 1967-91 in one research clinic in Reykjavik. SUBJECTS AND METHODS: The population in this survey were Icelandic Caucasian males and females, born 1907-35 and therefore 34-79 years old when their examination was performed. Altogether 9139 males and 9773 females attended, and of those 267 males and 210 female were NIDDM as defined by a questionnaire or an oral glucose tolerance test. Other factors measured in the study included systolic and diastolic blood pressure, fasting total cholesterol, triglycerides, uric acid, smoking habits, height, and weight. The causes of death were determined by a review of all death certificates. Results. The relative risk of death from CHD (95% confidence limits), independently associated with NIDDM, was 2.0 (1.5-2.6) for males and 2.4 (1.6-3.6) for females. The relative risk of death from all causes was 1.9 (1.6-2.3) and 1.7 (1.3-2.1), respectively, for male and female diabetic patients. CONCLUSIONS: Non-insulin dependent diabetes mellitus carried twice the risk of CHD death in both sexes, independently of other risk factors. The diagnosis of NIDDM at the age 55 years reduced an individual's life expectancy by about five years, mostly because of increased CHD death rate.

Incidence and prevalence of recognised and unrecognised myocardial infarction in women. The Reykjavik Study.

AIMS: The incidence and prevalence of recognised and unrecognised myocardial infarction were determined in the Icelandic cohort study of 13,000 women (the Reykjavik Study), followed for up to 29 years (mean 15 years). METHODS AND RESULTS: Women attending the Reykjavik Study, born between 1908 and 1935, were examined in five stages from 1968 to 1991. A health survey included history and ECG manifestations of coronary heart disease. Data retrieved from hospitals, autopsy records and death certificates identified 596 fatal and non-fatal myocardial infarctions to the end of 1992 (61 prior to examination, 320 non-fatal and 215 fatal). The incidence of recognised myocardial infarction ranged from 22 cases/100,000/year at 35-39 years to 1800 cases/100,000/year at 75-79 years. The incidence of unrecognised myocardial infarction ranged from 18 cases/100,000/year at 35 years to 219 cases/100,000/year at 75 years. Thirty-three percent of non-fatal myocardial infarctions were unrecognised. More occurred in the younger age groups (40%) than in the older (27%). The prevalence of recognised myocardial infarction was influenced by age and calendar year. In 1990, it was 1.3/1,000 at 35 years and 60/1000 at 75 years. Prevalence showed a time trend, tripling in all age groups from 1968-1992. Fore unrecognised myocardial infarction, prevalence rose from 0.9/1000 at 35 years to 19.2/1000 at 75 years, although there was no evident time trend. CONCLUSION: Myocardial infarction in women is very age-dependent with both incidence and prevalence increasing continuously and steeply with age. There was a significant trend for an increase in prevalence of recognised myocardial infarction from 1968 to 1992. The proportion of unrecognised non-fatal infarctions ranged from 27% in the oldest age group to 40% in the youngest. On average, this form of coronary heart disease is as common as in men.

Iodine intake and the pattern of thyroid disorders: a comparative epidemiological study of thyroid abnormalities in the elderly in Iceland and in Jutland, Denmark.

Thyroid abnormalities are common in all populations, but it is difficult to compare results of epidemiological studies, because different methods have been used for evaluation. We studied the importance of the population iodine intake level for the prevalence rate of various thyroid abnormalities in elderly subjects. Random samples of elderly subjects (68 yr) were selected from the central person registers in Jutland, Denmark, with low (n = 423) and, in Iceland, with longstanding relatively high (n = 100) iodine intake. Females from Jutland had a high prevalence of goiter or previous goiter surgery (12.2%), compared with males from Jutland (3.2%) and females (1.9%) and males (2.2%) from Iceland. Abnormal thyroid function was very common in both areas, with serum TSH outside the reference range in 13.5% of subjects from Jutland and 19% of those from Iceland. In Jutland, it was mainly thyroid hyperfunction (9.7% had low, 3.8% had high serum TSH), whereas in Iceland, it was impaired thyroid function (1% had low, 18% had high serum TSH). All subjects with serum TSH more than 10 mU/L had autoantibodies in serum, but antibodies were, in general, more common in Jutland than in Iceland. Thus, thyroid abnormalities in populations with low iodine intake and those with high iodine intake develop in opposite directions: goiter and thyroid hyperfunction when iodine intake is relatively low, and impaired thyroid function when iodine intake is relatively high. Probably, mild iodine deficiency partly protects against autoimmune thyroid disease. Thyroid autoantibodies may be markers of an autoimmune process in the thyroid or secondary to the development of goiter.

[Third degree atrioventricular block.].

OBJECTIVE: Third degree atrioventricular block is considered present when none of the atrial impulses are conducted to the ventricles because of a disruption in the conducting system. Third degree atrioventricular block is usually considered a serious sign but most studies have been performed on hospitalized patients or certain professional groups. The objective of this study was to find the prevalence of third degree atrioventricular block in a representative population sample and estimate its prognostic significance. MATERIAL AND METHODS: In the Reykjavik Study, a prospective cardiovascular population study, 9139 men and 9773 women aged 33-79 years were exam notined in 1967-1991. A standard electrocardiogram was taken from all persons examined and coded according to the Minnesota code. RESULTS: Third degree atrioventricular block was found in 11 persons, seven males and four females, an overall prevalence of 0.04%. All these individuals had signs of arrythmia on electrocardiograms taken later, and in addition some other heart disease. The heart block was temporary in seven individuals (64%) but six (55%) needed a pacemaker. CONCLUSIONS: The prevalence of third degree atrioventricular block in this general population was low but nevertheless considerably higher than previously reported. The block was temporary in the majority of subjects. All had some underlying heart disease which seemed to affect the prognosis more than the heart block. In this survey fewer subjects than expected were found to need a pacemaker.

[The relationship of education and mortality with special concern to coronary heart disease mortality. The Reykjavik Study.].

OBJECTIVE: Coronary heart disease is a leading cause of death in the Western world and coronary heart disease mortality has been connected with socio-economic status. Formerly, coronary heart disease mortality was higher xamong those with higher educational achievement, but recent research has shown this relationship to have been reversed. To assess this in Iceland, a prospective study of the relationship between education and coronary heart disease mortality as well as mortality due to all causes was performed. MATERIAL AND METHODS: This study was a part of the Reykjavik Study. The participants (18,912) were divided into four groups according to education. The relationship between education and mortality was assessed with the Cox proportional hazards model, using the group of lowest educational status as a reference. Corrections were made for age and year of examination along with risk factors (cholesterol, triglycerides, systolic blood pressure, glucose tolerance and smoking). RESULTS: A statistically significant negative relationship between education and coronary heart disease mortality was found for men and women (p<0.02 and p<0.01 respectively). Mortality risk of the highest educational group was 66% of the lowest group for men and 23% for women. The relationship was present after adjustment for risk factors, but significant for men only (p<0.03 and p<0.10 respectively). CONCLUSIONS: Education has a significant independent protective effect against coronary heart disease mortality in men. The same relationship is probably present among women, but fewer deaths had occurred. Educational status was a strong predictor of mortality and known risk factors only explained a small part of the mortality difference between various educational groups. Higher education was also associated with lowered mortality due to all causes.

Risk factors for malignant diseases: a cohort study on a population of 22,946 Icelanders.

The records of a cohort of 11,580 females and 11,366 males participating in an Icelandic cardiovascular risk factor study were linked with the Icelandic Cancer Registry, identifying 1,785 males and 1,490 females who had been registered with neoplastic diseases from 1968 to 1995. The interval between the time of measurement of the variables and the diagnosis of the malignancy ranged from 4 to 27 years. The variables consisted of answers from a questionnaire on smoking and the use of hypertensive drugs and anthropometric and biochemical measurements. Cox's regression was applied to analyze the predictive power of the variables on the risk of cancer after the first examination at the Heart Preventive Clinic, Reykjavík. Univariate analyses, adjusted for age, were performed for each variable and each major site. Within each major site, multivariate regression analysis was applied for variables that were found significantly (10% level in univariate analysis) positive or negative as risk factors. The results show that smoking is the most important risk factor, negative only for endometrium. For lung cancer, the risk is twice as strong for females as it is for males, whereas for pancreas, males have a relative risk ratio of 4.5, compared with 2.4 for females. Height is a risk factor for all sites for each sex, for breast in females, and for kidney in males. Several anthropometric risk factors were studied. Some of these can describe positive or negative relative risk ratios for cancer, and their use may shed light on cancer pathogenesis. Serum cholesterol is a negative risk factor for breast cancer in females, but triglycerides are a positive risk factor for cervix cancer in females and for colon or rectum and thyroid cancer in males. Serum glucose is a positive risk factor for prostate cancer and a negative risk factor for lymphomas and leukemias.