Blood pressure and the global burden of disease 2000. Part 1: estimates of blood pressure levels.

OBJECTIVE: To provide global estimates of blood pressure by age and sex for adults aged > or = 30 years, by WHO subregion. DESIGN AND METHODS: Data were obtained from studies identified in a literature review of population-based surveys. These were complemented by data from MONICA and INTERSALT studies. Estimates of the shape of the age-systolic blood pressure (SBP) association were made from survey data utilizing parametric and non-parametric analyses. A linear sex-specific association of SBP with age was demonstrated from 30 to 70 years in females and 20 to 70 years for males in each subregion. Mean age- and sex-specific estimates of SBP were estimated for each WHO subregion separately, based on study and country-weighted SBP data. RESULTS: Analyses were based on data from about 230 surveys and over 660 000 participants. Age-specific mean SBP values ranged from 114 to 164 mmHg for females, and 117-153 mmHg for males. Females typically had lower SBP levels than males in the 30-44-year age groups, but in all subregions, SBP levels rose more steeply with age for females than males. Therefore, SBP levels in those aged > or = 60 years tended to be higher in females. Subregions with consistently high mean SBP levels included parts of eastern Europe and Africa. Mean SBP levels were lowest in south-east Asia and parts of the western Pacific. CONCLUSIONS: These global estimates of blood pressure by age, sex and subregion show considerable variation in estimated levels. The lack of data in developing countries is substantial, and this is an important limitation given the role of blood pressure in increasing cardiovascular disease levels.

Blood pressure and the global burden of disease 2000. Part II: estimates of attributable burden.

OBJECTIVES: To provide estimates of the global burden of disease attributable to non-optimal blood pressure by age and sex for adults aged > or = 30 years, by WHO subregion. METHODS: Estimates of attributable burden were made using population impact fractions, which used data on mean systolic blood pressure levels, disease burden [in deaths and/or disability-adjusted life years (DALYs)] and relative risk corrected for regression dilution bias. Estimates were made of burden attributable to a population distribution of blood pressure with a mean systolic blood pressure of greater than 115 mmHg. RESULTS: Globally, approximately two-thirds of stroke and one-half of ischaemic heart disease were attributable to non-optimal blood pressure. These proportions were highest in the more developed parts of the world. Worldwide, 7.1 million deaths (approximately 12.8% of the global total) and 64.3 million DALYs (4.4% of the global total) were estimated to be due to non-optimal blood pressure. Overall approximately, two-thirds of the attributable burden of disease occurred in the developing world, approximately two-thirds in the middle age groups (45-69 years) and approximately one-half occurred in those with systolic blood pressure levels between 130 and 150 mmHg. CONCLUSIONS: The burden of non-optimal blood pressure is almost double that of the only previous global estimates, which is largely explained by the correction for regression dilution adopted in these analyses. High blood pressure is a leading cause of global burden of disease, and most of it occurs in the developing world.

The underlying risk of death after myocardial infarction in the absence of treatment.

BACKGROUND: The underlying risk of death in the absence of treatment after a myocardial infarction (MI) is poorly documented. METHODS: Analysis of 23 published studies in which 14 211 patients were followed prospectively after MI; 6817 deaths were recorded. We restricted the analysis to studies in which follow-up was completed by 1980 to quantify the underlying risk in the absence of effective treatments. RESULTS: After a first MI, on average, 23% of patients died before reaching the hospital and another 13% died during hospital admission; these rates increased with age. After hospital discharge cardiovascular mortality was approximately 10% in the first year and 5% per year thereafter, rates that were unrelated to age or sex. The yearly death rate of 5% persisted indefinitely; after 15 years, cumulative cardiovascular mortality was 70%. After a subsequent MI, 33% of patients died before reaching the hospital, and 20% died in hospital. After discharge, cardiovascular mortality was approximately 20% in the first year and 10% per year thereafter, rates again unrelated to age and sex. Approximately a third of all heart disease deaths occurred minutes after the first MI, a sixth during the first hospitalization, and half after a subsequent MI, which could occur many years after the first. CONCLUSIONS: In persons with a history of MI, cardiovascular mortality in the absence of treatment is high-5% per year after a first MI and 10% per year after a subsequent MI, persisting for many years and probably for the rest of a person's life. The high mortality rate emphasizes the need to ensure that everyone who has had an MI, even years previously, receives effective preventive treatment.

Environmental tobacco smoke and ischemic heart disease.

Cohort and case control studies show a 30% excess risk of ischemic heart disease in nonsmokers whose spouses smoke compared with that in nonsmokers whose spouses do not smoke. There is a nonlinear dose-response; the excess risk from actively smoking 20 cigarettes/day is only 80%. Large cohort studies of active smoking support the nonliner dose-response (the excess risk in smokers of 5 cigarettes/day is about 50%). Animal studies show a pronounced vascular effect of environmental tobacco smoke. In experimental studies passive and active smoking have similar effects on platelet aggregation. The collective evidence supports a significant effect of low dose tobacco smoke exposure in causing ischaemic heart disease.