Do changes in cardiovascular risk factors explain changes in mortality from stroke in Finland?

OBJECTIVES--To estimate the extent to which the changes in the main cardiovascular risk factors (blood pressure, smoking, and serum cholesterol concentration) can explain the observed changes in mortality from stroke in Finland during the past 20 years. DESIGN--Predicted changes in mortality from cerebrovascular disease mortality were calculated by a proportional hazards model from data obtained in cross sectional population surveys in 1972, 1977, 1982, 1987, and 1992. Predicted changes were compared with the observed changes in mortality statistics. SETTING--North Karelia and Kuopio provinces, Finland. SUBJECTS--16,741 men and 16,389 women aged 30-59 randomly selected from the national population register, of whom 14,054 men and 14,546 women participated. MAIN OUTCOME MEASURES--Levels of risk factors and predicted and observed changes in mortality from cerebrovascular disease. RESULTS--The observed changes in diastolic blood pressure, total serum cholesterol concentration, and smoking in the population from 1972 to 1992 predicted a 44% fall in mortality from stroke in men and changes in diastolic blood pressure and smoking predicted a 34% fall in women. The observed fall in mortality from stroke was 66% in men and 60% in women. CONCLUSIONS--Two thirds of the fall in mortality from stroke in men and half in women can be explained by changes in the three main cardiovascular risk factors.     

Decline in mortality from coronary heart disease in Finland from 1969 to 1979.

The trends in mortality from coronary heart disease in the 1970s and the differences in trends between counties within Finland were calculated from official mortality statistics among the population aged 35 to 64 years. During this period coronary mortality declined by a mean of 1.1% for men and 2.3% for women annually in the whole of Finland. A community based cardiovascular control programme was started in 1972 in North Karelia, a county in the east of Finland. The decline in coronary mortality in this county between 1969 and 1979 was 24% in men and 51% in women. The decline in the rest of Finland over the same period was 12% in men and 24% in women. The decline in North Karelia was greater than that in other counties of Finland for both men and women and that difference exceeded random variation, with over 95% likelihood for both sexes. Even with adjustment for rates before 1974 with cross-county multiple regression analyses the difference persisted. Although further studies are needed, the changes in coronary mortality in North Karelia suggest that the preventive programme has been effective.     

Temporal changes and rural-urban differences in cardiovascular disease risk factors and mortality in China.

We summarize several studies, from the last 10 years, of temporal changes and rural-urban differences in the risk factors of cardiovascular disease (CVD) in China to indicate the influences of economic modernization. Two national blood pressure surveys have shown that the prevalence of hypertension increased from 5.1% to 7.7% between 1958-1959 and 1979-1980. Throughout China hypertension is more prevalent in urban areas than in rural areas. Within the Shanghai region body mass index, blood pressure, and total serum cholesterol were higher in urban districts than in rural areas. Rural-urban differences in lipid levels were also found in the Beijing and Guangzhou regions. A related four-year followup study showed that total serum cholesterol and triglycerides increased markedly in both urban and rural areas of Guangzhou. In Shanghai part-time farmers who worked in factories had a higher age-adjusted prevalence of definite hypertension than farmers who worked full-time in the fields (5.0% versus 2.3%). In a prospective study in Wuhan a new productivity-based salary system was associated with increased serum cholesterol and blood pressure. Age-adjusted CVD mortality increased from 1973 to 1982 in a rapidly industrializing county in the Shanghai metropolitan region. The results from several studies indicate that China is undergoing the expected increase in modernization-related CVD risk factors and mortality, especially in urban metropolitan regions.     

Chlamydia pneumoniae infection and mortality from ischaemic heart disease: large prospective study

ObjectiveTo determine whether there is an independent association between infection with Chlamydia pneumoniae and ischaemic heart disease.DesignProspective study using a nested case-control design.SettingMedical centre in London run by BUPA, a private medical organisation.Participants21 520 professional men aged 35-64 who attended for a medical examination in London between 1975 and 1982.ResultsThe distributions of concentrations of IgG and IgA antibodies to C pneumoniae were similar in the 647 men who subsequently died of ischaemic heart disease and in 1294 age matched controls who did not. There was no material association with heart disease irrespective of the cut-off point chosen to define seropositivity. At a cut-off point that defines 15% of controls as positive, for example, the odds ratios were 1.26 (95% confidence interval 0.95 to 1.68) for IgG and 1.09 (0.82 to 1.43) for IgA.ConclusionsNo material association was found between infection with C pneumoniae and ischaemic heart disease. The size and prospective design of the study and the socioeconomic homogeneity of the cohort minimise both random and systematic error.     

Change in alcohol consumption and risk of death from all causes and from ischaemic heart disease.

OBJECTIVE--To examine the association between alcohol consumption and mortality from all causes and from ischaemic heart disease with a focus on differentiating between long term abstainers and more recent non-drinkers. DESIGN--Cohort study of changes in alcohol consumption from 1965 to 1974 and mortality from all causes and ischaemic heart disease during 1974-84. SETTING--Population based study of adult residents of Alameda County, California. SUBJECTS--2225 women and 1845 men aged 35 and over in 1965. MAIN OUTCOME MEASURES--Alcohol consumption in 1964 and 1974 and mortality from all causes and from ischaemic heart disease during 1974-84. RESULTS--There was a significantly higher risk of death from all causes and from ischaemic heart disease in women who gave up drinking between 1965 and 1974 than in women who continued to drink (relative risk 1.72, 95% confidence interval 1.11 to 2.66, and 2.75, 1.44 to 5.23, for all causes and ischaemic heart disease respectively). A significant increase in risk was not seen in men who gave up drinking (1.32, 0.87 to 2.01, and 0.95, 0.41 to 2.20, respectively). Among men, long term abstainers compared with drinkers were at increased risk of death from all causes and from ischaemic heart disease, though the associations were not significant (1.40, 0.98 to 2.00, and 1.40, 0.76 to 2.58, for all causes and ischaemic heart disease respectively). CONCLUSION--Some of the increased risk of death from all causes and from ischaemic heart disease associated with not drinking in women seems to be accounted for by higher risks among those who gave up drinking. Men who are long term abstainers may also be at an increased risk of death. The heterogeneity of the non-drinking group should be considered when comparisons are made with drinkers.     

Dental disease and risk of coronary heart disease and mortality.

OBJECTIVE--To investigate a reported association between dental disease and risk of coronary heart disease. SETTING--National sample of American adults who participated in a health examination survey in the early 1970s. DESIGN--Prospective cohort study in which participants underwent a standard dental examination at baseline and were followed up to 1987. Proportional hazards analysis was used to estimate relative risks adjusted for several covariates. MAIN OUTCOME MEASURES--Incidence of mortality or admission to hospital because of coronary heart disease; total mortality. RESULTS--Among all 9760 subjects included in the analysis those with periodontitis had a 25% increased risk of coronary heart disease relative to those with minimal periodontal disease. Poor oral hygiene, determined by the extent of dental debris and calculus, was also associated with an increased incidence of coronary heart disease. In men younger than 50 years at baseline periodontal disease was a stronger risk factor for coronary heart disease; men with periodontitis had a relative risk of 1.72. Both periodontal disease and poor oral hygiene showed stronger associations with total mortality than with coronary heart disease. CONCLUSION--Dental disease is associated with an increased risk of coronary heart disease, particularly in young men. Whether this is a causal association is unclear. Dental health may be a more general indicator of personal hygiene and possibly health care practices.     

Travel and ischaemic heart disease.

The hypothesis that travel precipitates acute ischaemic heart disease (IHD) was tested in a case-control study of holidaymakers admitted to hospital in Great Yarmouth. The distance that patients with IHD had travelled to reach Great Yarmouth was on average greater than that travelled by patients with other diseases. I conclude that the greater distances travelled by patients with IHD may have helped to precipitate the attack.     

Decline in ischaemic heart disease in Iceland and change in risk factor levels.

OBJECTIVE--To monitor trends in mortality and morbidity due to ischaemic heart disease and compare these with observed levels of risk factors from population surveys. DESIGN--Analysis of trends in death rates from ischaemic heart disease in Iceland compared with expected rates computed from population surveys. Risk factor levels together with beta factors obtained from Cox''s regression analysis were used to compute expected death rates. Trends in morbidity due to acute myocardial infarction were assessed and secular trends in dietary consumption compared with trends in cholesterol concentrations. SETTING--Reykjavik, Iceland (total population 250,000; over half the population live in Reykjavik). SUBJECTS--12,814 randomly selected residents in the Reykjavik area aged 45-64 (6623 men, 6191 women; 72% and 80% of those invited). MAIN OUTCOME MEASURES--Age adjusted rates of myocardial infarction and deaths from ischaemic heart disease. Expected risk from risk factor levels (smoking, total serum cholesterol concentration, systolic blood pressure) at each unique survey visit. RESULTS--Mortality from ischaemic heart disease has decreased by 17-18% since 1970. During 1981-6 the myocardial infarction attack rate in men under 75 decreased by 23%. A decrease occurred in the level of all three major risk factors after 1968. The fall in the serum cholesterol concentration coincided with a reduction in consumption of dairy fat and margarine. The calculated reduction in risk for the age group 45-64 was about 35%, which was closely similar to the observed decrease in mortality due to ischaemic heart disease in that age group. CONCLUSION--The reduction in mortality from ischaemic heart disease was substantially due to a decreased incidence of myocardial infarction and could be attributed largely to the reduction in risk factors.     

Helicobacter pylori infection and mortality from ischaemic heart disease: negative result from a large,prospective study.

OBJECTIVE: To determine whether there is an independent association between Helicobacter pylori infection of the stomach and ischaemic heart disease. DESIGN: Prospective study with measurement of IgG antibody titres specific to H pylori on stored serum samples from 648 men who died from ischaemic heart disease and 1296 age matched controls who did not (nested case-control design). SUBJECTS: 21,520 professional men aged 35-64 who attended the British United Provident Association (BUPA) medical centre in London between 1975 and 1982 for routine medical examination. MAIN OUTCOME MEASURE: Death from ischaemic heart disease. RESULTS: The odds of death from ischaemic heart disease in men with H pylori infection relative to that in men without infection was 1.06 (95% confidence interval 0.86 to 1.31). In a separate group of 206 people attending the centre, plasma fibrinogen was virtually the same in those who were positive for H pylori (2.62 g/l) and those who were negative (2.64 g/l). CONCLUSIONS: A study that by its size and design minimised both random error and socioeconomic bias found no relation between H pylori infection and ischaemic heart disease. The validity of the study was shown by its confirmation of the recognised association between H pylori infection and stomach cancer (odds ratio 4.0 (1.9 to 8.2); P < 0.001). Eradication of H pylori infection may greatly reduce the incidence of stomach cancer, one of the most common causes of death from cancer worldwide, but it cannot be expected to have any effect in preventing ischaemic heart disease.     

Dietary factors in the fall in coronary heart disease mortality.

The role of dietary change in the fall in heart disease mortality has been hotly debated. Three countries, Australia, USA and UK with equal 'care' and sophistication of surgical techniques have shown different timing in the beginning of the decline of this 'epidemic'; around the mid 1960s in the first two countries, but not until the late 1970s for the UK. The cause of this difference may be the changing food habits of their populations. Using food disappearance data, apparent consumption of butter and margarine show opposite trends (butter down and margarine up) predating the decline in mortality in both the USA and Australia by at least 7 years and also in the UK, but at a later time, (about 1970). Changes in adipose tissue linoleate, a marker for polyunsaturated fat intake, support this indirect evidence, with depot levels rising in the USA from the 1960s and 10 years later in the UK. Other evidence support the view of decreasing saturated fat intake and increasing polyunsaturated intake prior to 1960 in the USA. Although many factors must contribute to the decline in mortality from CHD, change in dietary P/S ratio would seem to be the major dietary contributor.     

Snoring as a risk factor for ischaemic heart disease and stroke in men.

The association of snoring with ischaemic heart disease and stroke was studied prospectively in 4388 men aged 40-69. The men were asked, in a questionnaire sent to them, whether they snored habitually, frequently, occasionally, or never. Hospital records and death certificates were checked for the next three years to establish how many of the men developed ischaemic heart disease or stroke: the numbers were 149 and 42, respectively. Three categories of snoring were used for analysis: habitual and frequent snorers (n = 1294), occasional snorers (n = 2614), and non-snorers (n = 480). The age adjusted relative risk of ischaemic heart disease between habitual plus frequent snorers and non-snorers was 1.91 (p less than 0.01) and for ischaemic heart disease or stroke, or both, 2.38 (p less than 0.001). There were no cases of stroke among the non-snorers. Adjustment for age, body mass index, history of hypertension, smoking, and alcohol use did not significantly decrease the relative risks, which were 1.71 (p greater than 0.05) for ischaemic heart disease and 2.08 (p less than 0.01) for ischaemic heart disease and stroke combined. At the beginning of follow up in 1981, 462 men reported a history of angina pectoris or myocardial infarction. For them the relative risk of ischaemic heart disease between habitual plus frequent snorers and non-snorers was 1.30 (NS); for men without previous ischaemic heart disease 2.72 (p less than 0.05). Snoring seems to be a potential determinant of risk of ischaemic heart disease and stroke.