Concordance of ischemic heart disease in the NHLBI twin study after 14-18 years of follow-up

Morbidity and mortality were assessed in the NHLBI twin study at the end of 1987. Deaths were greater in DZ twins (58/520, 11.2%) than MZ twins (38/508, 7.5%). Ischemic heart disease concordances were 2.3 times higher in MZ pairs and 2.8 times higher in DZ pairs than expected based on the prevalence of ischemic heart disease in the cohort. Family history scores for heart disease, calculated 14-18 years earlier at entry to the study, were significantly higher in DZ pairs where one or both members later developed ischemic heart disease and in corcordant MZ pairs than in twin-pairs without any subsequent heart disease. Concordance rates were not significantly different between MZ and DZ pairs. The results agree with previous suggestions that selection at enlistment into the armed services over 40 years ago, as well as later volunteering for the NHLBI twin study, resulted in a decline in the number of concordant MZ pairs.     

The NHLBI male veteran twin study data

The National Heart, Lung and Blood Institute (NHLBI) twin study is a collaborative, longitudinal study of the role of genetic risk factors on subsequent cardiovascular disease processes in 514 pairs of white, male World War II and Korean veteran twins born between 1917 and 1927. This paper describes the sampling procedures and zygosity determination at the initial examination, participation by the cohort members at later examinations, and a summary of the variables provided for Genetic Analysis Workshop 8 (GAW8). © 1993 Wiley-Liss, Inc.     

Can cardiovascular risk factors and lifestyle explain the educational inequalities in mortality from ischaemic heart disease and from other heart diseases? 26 year follow up of 50 000 Norwegian men and women

OBJECTIVE: Investigate the degree to which smoking, physical activity, marital status, BMI, blood pressure, and cholesterol explain the association between educational level and ischaemic heart disease (IHD) mortality and other forms of cardiovascular mortality, with main focus on IHD mortality. DESIGN: Prospective health examination survey study conducted in the period 1974-78. SETTING: Oppland, Sogn og Fjordane, and Finnmark counties in Norway. PARTICIPANTS: The sample comprised 22,712 men and 21,972 women, aged 35-49 at screening. The subjects were followed up with respect to mortality throughout year 2000. MAIN RESULTS: 4342 men and 2164 women died during the follow up, 1343 men and 258 women of IHD. IHD mortality risk was higher for people with low education compared with people with high education, and people with low education had more adverse risk factors. After adjustment for smoking the IHD mortality relative risk (RR) with 95% confidence limits, in the low educational group decreased from 1.33 (1.18 to 1.50) to 1.16 (1.03 to 1.31) for men, and from 1.72 (1.23 to 2.41) to 1.58 (1.13 to 2.22) for women. Further adjustment for physical activity, marital status, BMI, blood pressure, and cholesterol reduced the RR to 1.03 (0.91 to 1.17) for men and 1.24 (0.88 to 1.75) for women. CONCLUSIONS: Unfavourable cardiovascular risk factors and high IHD mortality are more prevalent among less educated than their highly educated peers. After simultaneous adjustment for all recorded risk factors, the excess IHD mortality in the low educational groups was reduced by 91% for men and 67% for women.     

Genetic heritability and common environmental components of resting and stressed blood pressures, lipids, and body mass index in Utah pedigrees and twins

The relative contributions of genes and shared environment to cardiovascular risk factors were studied in twins and pedigrees in 1983-1985. Sitting, standing, isometric hand grip, bicycling, and mentally stressed (serial subtraction) blood pressures were obtained from 146 male monozygous twins, 162 male dizygous twins, and 1,102 healthy adults in 67 Utah pedigrees. Fasting total plasma cholesterol, triglycerides, high density lipoprotein cholesterol (HDL), and body mass index were also measured. Heritability was estimated before and after adjusting for 12 environmental variables (measures of socioeconomic status; personality types; exercise levels; use of tobacco, alcohol, coffee, etc.) by using age-adjusted twin intraclass correlations. These heritabilities were compared with those obtained from a variance components analysis of the pedigree data separating genetic and common household effects. Sitting and standing blood pressure heritability estimates were much higher from twin than from pedigree data (39-63% in twins vs. 16-22% in pedigrees), as were those for cholesterol and triglycerides (65 and 75% from twins vs. 42 and 37% from pedigrees) and body mass index (51 vs. 21%). Estimates were similar for heritability of HDL cholesterol (51 vs. 45%). Most of the stressed blood pressure heritabilities were similar to sitting blood pressure estimates. No common household effect (except for adjusted HDL cholesterol (24%), p less than 0.01) was statistically significant for the lipids, blood pressures, or body mass index. Environmental variables correlated much better in monozygous twins and spouses than in dizygous twins, brothers, or sisters. Spouse correlations for lipids, blood pressures, and body mass index were low, with a maximum of 0.12 (p less than 0.05) for HDL cholesterol. We conclude that genes contribute much more than shared environment to the well-recognized familial correlation of blood pressures, lipids, and body mass index.     

Nongenetic influences of obesity on other cardiovascular disease risk factors: an analysis of identical twins.

The importance of genetic influences on obesity has been emphasized recently. We conducted matched co-twin analyses of 250 pairs of White, male, monozygotic twins from the National Heart, Lung, and Blood Institute (NHLBI) Twin Study. Entirely in the absence of genetic influences, obesity was significantly associated with systolic and diastolic blood pressures; one-hour, post-load glucose; total, LDL-, and HDL-cholesterol; and triglycerides among these 42-55 year old men. Similar results were obtained in longitudinal analyses of weight change during adulthood (from mean age of 20 to mean age of 48 years) and risk factor status at middle-age. These results indicate that behaviors and environmental exposures that occur later in life are responsible, at least in part, for the associations between adult obesity and cardiovascular disease risk, supporting the appropriateness of weight reduction efforts during adulthood.     

Income and risk of ischaemic heart disease in men and women in a Nordic welfare country

BACKGROUND: The inverse relation between ischaemic heart disease (IHD) and income is well known among men, but it remains to be clarified whether the relationship between social gradient and IHD is similar for men and women. The present study explores the associations between income and IHD in men and women in a Nordic country. METHODS: We used data from two prospective population studies conducted in Copenhagen. A total of 22 782 subjects, 54% women, with initial examination between 1964 and 1992 were followed until 1996 for hospital admission or death from IHD. We performed survival analyses, taking traditional cardiovascular risk factors into account, and estimated IHD-free life expectancy by household income in men and women. RESULTS: During follow-up, 1803 men and 1258 women experienced an event of IHD (21% fatal). The hazards by deciles of income showed a non-linear graded inverse effect of income, with a large group of middle-income in which income was not associated with risk of IHD. The hazard ratio for highest versus lowest deciles was 0.53 (95% CI: 0.44-0.65). The association was attenuated by adjustment for risk factors, but remained statistically significant. The associations were similar for both sexes. Median IHD-free life expectancy for low-income versus high-income groups was reduced by 9.4 and 7.0 years in men and women, respectively. CONCLUSIONS: The effect of household income on risk of IHD was graded and similar for men and women. The difference between high and low income, regarding IHD-free life expectancy, was considerable.     

Family history of ischemic heart disease with respect to mean twin-pair cholesterol and subsequent ischemic heart disease in the NHLBI twin study

This study examines the independent and interactive effects of family history scores (FHxS) for the prevalence of ischemic heart disease with plasma lipids and subsequent morbidity and mortality from ischemic heart disease. FHxS were calculated for 514 sets of middle aged male twins who participated in the entry examination of the NHLBI Veteran twin study in 1969-1973. Comparison of the FHxS with the level of plasma total cholesterol and HDL cholesterol (HDLc) paralleled earlier reported findings in young adults; individuals with high total cholesterol in two exams 8-12 years apart had significantly (P less than .01) higher FHxS. The same relationship was noted when using the mean twin-pair cholesterol level at the initial exam when the twins were in their 40s. Using the pair means over two exams as the cotwins aged into their 50s, the association of FHxS with total cholesterol declined and pairs with HDLc persistently in the highest quintile at both exams had significantly (P less than .01) lower FHxS. The changes in the pattern of association of lipid fractions with FHxS with age parallel the reported age decline of total cholesterol as a risk factor for heart disease. Assessment of ischemic heart disease events up to January 1988 revealed a highly significant association (P less than .0001) of later ischemic heart disease events with FHxS. At each level of lipid categorization pairs who later had events had higher FHxS than those without any subsequent heart disease; these differences were significant in all but the low risk lipid groups (low total cholesterol, high HDLc, and low total cholesterol/HDLc ratio). We conclude that FHxS is related to total cholesterol and HDLc but also is an independent predictor of subsequent ischemic heart disease after 14-18 years of follow-up.     

Lifestyle factors in monozygotic and dizygotic twins

In examining genetic influences on biological variables using twins, it may be important to examine the distribution between and within twin pairs of demographic and lifestyle factors that may themselves affect the biological variable being studied. We explored the distribution of demographic and lifestyle factors that may affect blood lipid levels or ischaemic heart disease (IHD) risk among a sample of 106 monozygotic (MZ) and 94 like-sex dizygotic (DZ) twin pairs. In our sample, MZ twins were statistically significantly different from DZ twins only in marital status, cigarette smoking habits, and the ratio of polyunsaturated to saturated fat (P:S ratio) in their dietary intake. The latter variable was among many dietary variables examined (using 4-day weighed food diaries), and the size of the difference in intake was small. When comparisons were made of the similarities within twin pairs, we found members of MZ twin pairs to be statistically significantly closer than DZ twins in educational achievement, occupation, cigarette smoking, and exercise habits, and the number of days a week on which alcohol was consumed. These last three variables were consistently closer among twins with closer contact than among those with a smaller degree of current shared environment. For 12 of the 13 nutrients examined, the within-pair correlations were higher for MZ than for DZ twins, although our test for significant genetic variance showed statistical significance only for intake of complex carbohydrates. We conclude that MZ twins share demographic and lifestyle factors that might influence the risk of IHD and blood lipid levels to a greater degree than do DZ twins, although it is difficult to say if these similarities in lifestyle result from genetic influences or not. Nevertheless, ascribing differences between correlations in MZ and DZ twin pairs for lipid levels as being purely "genetic"--as implicit in conventional measures of heritability--is likely to overestimate the influence of genetic factors.     

Physical activity and mortality: is the association explained by genetic selection?

Public health recommendations promote physical activity to improve health and longevity. Recent data suggest that the association between physical activity and mortality may be due to genetic selection. Using data on twins, the authors investigated whether genetic selection explains the association between physical activity and mortality. Data were based on a postal questionnaire answered by 13,109 Swedish twin pairs in 1972. The national Cause of Death Register was used for information about all-cause mortality (n=1,800) and cardiovascular disease mortality (n=638) during 1975-2004. The risk of death was reduced by 34% for men (relative risk=0.64, 95% confidence interval: 0.50, 0.83) and by 25% for women (relative risk=0.75, 95% confidence interval: 0.50, 1.14) reporting high physical activity levels. Within-pair comparisons of monozygotic twins showed that, compared with their less active co-twin, the more active twin had a 20% (odds ratio=0.80, 95% confidence interval: 0.65, 0.99) reduced risk of all-cause mortality and a 32% (odds ratio=0.68, 95% confidence interval: 0.49, 0.95) reduced risk of cardiovascular disease mortality. Results indicate that physical activity is associated with a reduced risk of mortality not due to genetic selection. This finding supports a causal link between physical activity and mortality.     

Body mass index and cardiovascular disease mortality in Japan: the Ohsaki Study

OBJECTIVE: Although there is a clear positive association between obesity and the incidence and severity of cardiovascular disease, the association between underweight and cardiovascular disease is unclear. The objective of this study was to examine the relation between body mass index (BMI) and cardiovascular disease in Japan, where the proportion of the population that is underweight is relatively high. METHOD: A total of 43,916 Japanese adults (21,003 men and 22,913 women) aged 40 to 79 years who had no history of cancer, ischemic heart disease (IHD), or stroke participated in the baseline survey in 1994. Hazard ratios (HR) and their 95% confidence intervals (CIs) for death due to total cardiovascular disease, all strokes, ischemic stroke, hemorrhagic stroke, and IHD were calculated according to BMI by using Cox's proportional hazards regression models. The 22.5-24.9 kg/m(2) BMI category was used as the reference category in all analyses. RESULTS: There were U-shaped associations between BMI and total cardiovascular disease, all stroke, hemorrhagic stroke, and IHD mortality, and a J-shaped association between BMI and ischemic stroke mortality. Participants with a BMI <18.5 kg/m(2) had a significantly increased risk of total cardiovascular disease, all stroke, hemorrhagic stroke, and IHD mortality, and the multivariate HR (95% CI) was 1.62 (1.19-2.19), 1.50 (1.02-2.21), 2.11 (1.07-4.17), 1.83 (1.11-3.01), respectively. CONCLUSION: Underweight was substantially associated with hemorrhagic stroke and IHD mortality in Japan, while obesity was associated with increased risk of total cardiovascular disease mortality and mortality from individual cardiovascular diseases.     

Body mass index and cardiovascular disease in the Asia-Pacific Region: an overview of 33 cohorts involving 310 000 participants

BACKGROUND: Few prospective data from the Asia-Pacific region are available relating body mass index (BMI) to the risks of stroke and ischaemic heart disease (IHD). Our objective was to assess the age-, sex-, and region-specific associations of BMI with cardiovascular disease using individual participant data from prospective studies in the Asia-Pacific region. METHODS: Studies were identified from literature searches, proceedings of meetings, and personal communication. All studies had at least 5000 person-years of follow-up. Hazard ratios were calculated from Cox models, stratified by sex and cohort, and adjusted for age at risk and smoking. The first 3 years of follow-up were excluded in order to reduce confounding due to disease at baseline. RESULTS: A total of 33 cohort studies, including 310 283 participants, contributed 2 148 354 person-years of follow-up, during which 3332 stroke and 2073 IHD events were observed. There were continuous positive associations between baseline BMI and the risks of ischaemic stroke, haemorrhagic stroke, and IHD, with each 2 kg/m(2) lower BMI associated a 12% (95% CI: 9, 15%) lower risk of ischaemic stroke, 8% (95% CI: 4, 12%) lower risk in haemorrhagic stroke, and 11% (95% CI: 9, 13%) lower risk of IHD. The strengths of all associations were strongly age dependent, and there was no significant difference between Asian and Australasian cohorts. CONCLUSIONS: This overview provides the most reliable estimates to date of the associations between BMI and cardiovascular disease in the Asia-Pacific region, and the first direct comparisons within the region. Continuous relationships of approximately equal strength are evident in both Asian and Australasian populations. These results indicate considerable potential for cardiovascular disease reduction with population-wide lowering of BMI.     

Socioeconomic status and ischaemic heart disease mortality in middle-aged men: importance of the duration of follow-up. The Copenhagen Male Study

OBJECTIVES: The predictive value of some risk factors may diminish with increasing duration of follow-up. This study was performed to elucidate the role of socioeconomic status as a risk factor for ischaemic heart disease (IHD) mortality in middle-aged men, testing the hypothesis that the role of mediators of the association of socioeconomic status with risk of IHD would diminish with increasing length of follow-up. METHODS: A cohort of 5249 men aged 40-59 was established in 1971. Baseline data on social class and other confounder variables were collected, and the cohort was followed through registers for 8, 15, and 22 years. In all, 5028 without a history of myocardial infarction or angina pectoris were included in the follow-up. Four factors associated with either occupation or lifestyle were strong mediators of the association found between social class and risk of fatal IHD, and were more common in the lower social classes (classes IV and V): occasional demand for vigorous activity at work, low leisure time physical activity level, high alcohol consumption, and smoking. RESULTS: After the first 8 years, 78 men had died due to IHD, after 15 years: 222, and after 22 years: 411. Compared with social classes I, II, and III, the age-adjusted relative risk (RR) with 95% CI for classes IV and V was 1.69, P < 0.05 after the first 8 years; adjusted for the above potential risk factors the RR dropped to 1.09, P = NS. Corresponding RR after 15 years were 1.67, P < 0.001 and 1.33, P = NS; and after 22 years, 1.59, P < 0.001 and 1.36, P < 0.05. CONCLUSIONS: Risk factors with an uneven social distribution related to occupation and lifestyle were strong mediators of the association of socioeconomic status with risk of IHD. A quite strong explanatory potential persisted but diminished with length of follow-up.     

Debunking the 'only 50%' myth: prevalence of established risk factors in New Zealanders with self-reported ischaemic heart disease

OBJECTIVE: To estimate the prevalence of established risk factors for ischaemic heart disease (IHD) in New Zealand adults and compare the prevalence in adults with and without this disease. DESIGN: Data were obtained from the 2002/03 New Zealand Health Survey. Risk factor prevalence was determined by: self-reported doctor diagnosis of high blood pressure, high cholesterol and diabetes; self-report of smoking and physical inactivity; and measurement of obesity. Presence of IHD was based on self-report of heart disease (doctor diagnosed at age 25 years or over) together with current medical or past surgical treatment for this disease. Multiple logistic regression was used to determine prevalence rate ratios (PRRs) for males and females separately, adjusting for age, ethnicity and deprivation. RESULTS: The overall prevalence of IHD was 8%. Overall risk factor prevalences were in the range of 20-25% for each of high blood pressure, high cholesterol, smoking, obesity and physical inactivity, and approximately 5% for diabetes. Overall, 94-97% of adults with IHD had at least one risk factor (depending on how smoking was defined). The PRRs of IHD were highest for cholesterol (about 4.5), followed by blood pressure (about 2.3), with all other risk factors around 1.5. PAF estimates indicate that 80-85% of IHD was attributable to the presence of at least one risk factor for all age, gender and ethnic groups. CONCLUSIONS: Established risk factors account for 80-85% of the non-fatal burden of IHD in New Zealand. Limited research resources would be better used to evaluate which interventions are effective and efficient at reducing exposure of all population groups to known risk factors, rather than on identification of additional risk factors.     

Birth weight and risk of angina pectoris: analysis in Swedish twins

Objective: Intrauterine nutrition approximated by birth weight has been shown to be inversely associated with risk of coronary heart disease (CHD). By investigating the association within twin pairs discordant for disease, the influence of genetic and early environmental factors is substantially reduced. Methods: We have investigated the association between birth weight and angina pectoris in same-sexed twins with known zygosity included in the population-based Swedish Twin Registry. Self-reports of birth weight and angina pectoris were collected in a telephone interview between 1998 and 2000. The cohort analyses were based on 4594 same-sexed twins, and the within-pair analyses included 55 dizygotic and 37 monozygotic twin pairs discordant for angina pectoris. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by logistic regression. Results: Compared with birth weight between 2.0 and 2.9 kg, low birth weight (<2.0 kg) was associated with increased risk of angina pectoris in the twin cohort, (OR: 1.46; 95% CI: 1.14–1.87), but after adjustment for potential confounders the risk decreased, and did not reach significance. Within twin pairs discordant for angina pectoris, low birth weight was significantly associated with increased risk of angina pectoris within dizygotic twins (adjusted OR: 5.73; 95% CI: 1.59–20.67), but not within monozygotic twins (adjusted OR: 1.20; 95% CI: 0.40–3.58). Conclusions: The results suggest that genetic differences associated with foetal growth and adult risk of CHD may have affected previously reported associations between birth weight and CHD.     

Increasing inequality in ischaemic heart disease morbidity among employed men in Denmark 1981-1993: the need for a new preventive policy.

BACKGROUND: In the mid 1980s European governments committed themselves to the WHO goal 'reduced inequality in health by year 2000' according to which inequality in health should be reduced by 25% by the year 2000. The study aim is to estimate the time trend in relative risk due to ischaemic heart disease (IHD) morbidity in employment status groups in Denmark in the period from 1981 to 1993 and to recommend a strategy to reduce inequality in health. MATERIAL AND METHODS: The study dealt with change in relative risk of IHD in main employment status AND groups as measured in three successive cohorts. The cohorts were defined as all METHODS: gainfully employed men in Denmark as of 1 January 1981, 1986 and 1991, respectively. Information on employment was retrieved for the three previous years. The cohorts were followed for first admissions with IHD as the principal cause during 5, 5, and 3 years respectively. RESULTS: Managers and white collar workers had an average or low and decreasing relative risk while male blue collar workers had a high and increasing relative risk. Thus the social inequality in IHD is rapidly increasing. Some occupational groups are known to be at high risk. Some of these high-risk groups, such as bus drivers, even have an increasing relative risk. CONCLUSIONS: The general health education has been successful in the prevention of IHD in the high-status groups but has failed to reduce the risk among blue collar workers. Preventive measures against IHD should focus on occupational groups at high, increasing risk and the measures should tailor to their 'subculture.'     

The association between body height and coronary heart disease among Finnish twins and singletons

OBJECTIVE: An inverse association between body height and the incidence of coronary heart disease (CHD) has been observed. However, the mechanisms behind this association are still largely unknown. We will examine the role of genetic and familial factors behind the association in a large twin data set. DESIGN AND SETTING: The data were derived from the Finnish Twin cohort including 2438 singletons, 4073 monozygotic (MZ) twins, and 9202 dizygotic (DZ) twins aged 25-69 years at baseline in 1976. Incident CHD cases were derived from hospital discharge data and cause of death data between 1977 and 1995. Cox regression analysis and conditional logistic regression analysis were used. RESULTS: In population-level analyses no differences in the general risk of CHD between zygosity groups were found. The association between body height and CHD was similar between sexes and zygosity groups. When men and women in all zygosity groups were studied together an increased risk of CHD was found only among the shortest quartile (hazard ratio [HR] = 1.34, 95% CI: 1.14-1.57). Among the twin pairs discordant for CHD a suggestive increased risk for the shorter twin was seen among DZ twins (odds ratio [OR] = 1.19, 95% CI: 0.95-1.48) when men and women were studied together. CONCLUSION: An inverse association between body height and CHD was broadly similar between sexes and twin zygosity groups and was associated with short stature. Among discordant twin pairs we found a weak association among DZ twins but not MZ twins. This may suggest the role of genetic liability behind the association between body height and CHD.     

农村心血管病高危个体检出率及影响因素分析——基于河北两县的抽样调查

目的：初步了解我国农村地区心血管病高危个体的流行现状及影响因素.方法：在河北省鹿泉和安国两市（县）,采用分层随机抽样方法,每县分别选择12个村中20岁及以上成年人共2 033名进行体格检查和问卷调查.运用多因素logistic回归分析其影响因素.结果：加权调整心血管病高危个体检出率为20.0%,随年龄增长呈显著上升趋势（P〈0.001）.多因素logistic分析发现,除性别、年龄与之相关外,超重/肥胖、文化程度低以及体力活动缺乏也均与之显著相关.其中,肥胖者高危检出率为体重正常者的2.3倍,未上学者是高中及以上文化程度者的3.1倍,不干体力活者是每天干体力活者的2.1倍.结论：我国农村成人中心血管病高危个体已十分常见,其中受教育水平较低的人群比例更高.农村的心血管病防控亟需出台相关政策促进健康生活方式,保护弱势人群.     

The relationships between interest for and participation in health screening and risk of mortality: the Japan Collaborative Cohort Study

BACKGROUND: This study examined whether the interest in participation in health screening is associated with reduced mortality in Japan. METHODS: A total of 68,825 subjects, 40-79 years old, in 29 Japanese communities responded to a questionnaire including interest level and participation status in health screening during 1988-1990. Systematic surveillance was completed until the end of 1999, with 660,682 person-years of follow-up, and the causes of death were determined. RESULTS: Men and women with low/no interest in health screening had 24-94% higher mortality from cardiovascular disease (CVD) and all causes. Women, but not men, with non-participation in health screening had 18-24% excess risk of mortality from cardiovascular disease, cancer, and all causes. Men and women with low/no interest and non-participation in health screening had 23-47% excess risk of mortality from cardiovascular disease and all causes. A similar excess risk of mortality was found among men with low/no interest and participation in health screening, but such a trend was less evident among women. CONCLUSION: Men and women with lower interest and women with no participation in health screening were at high risk for cardiovascular disease and all-cause mortality. Additionally, men who participated but had lower interest in health screening are also considered as high risk for cardiovascular disease.     

Job categories and acute ischemic heart disease: a hospital-based, case-control study in Taiwan

BACKGROUND: Most studies of the relationship between work and acute ischemic heart disease (IHD) were performed in western populations, and the extent to which their findings hold in Asian populations is largely unknown. The purpose of this study was to examine the association between job categories and non-fatal, first episodes of acute IHD in Taipei, Taiwan. METHODS: A hospital-based, case-control design was used. Cases were patients with a first episode of non-fatal acute IHD who were admitted to the department of cardiology. Two controls without known cardiovascular disease were matched to each case for age, gender, and date of admission. A total of 119 cases and 238 controls were enrolled between April and September 2004. RESULTS: Compared with white-collar workers, blue-collar workers had a 5.3-fold (95% CI: 1.5, 18.5) increased risk of a first episode of non-fatal acute IHD, while self-employed workers and managers/professionals had a slightly lower odds ratio of 0.6 (95% CI: 0.1, 2.4) and 0.5 (95% CI: 0.1, 2.2), respectively. Hypertension, diabetes, obesity, physical inactivity, and sleep disturbance were significant risk factors for acute IHD. A clustering of the cardiovascular risk factors was found in blue-collar workers. CONCLUSIONS: Blue-collar workers had a 5.3-fold increased risk of a first event of non-fatal acute IHD compared with white-collar workers, and this increased risk was associated with a clustering of cardiovascular risk factors.