Decline in US stroke mortality in the era before antihypertensive therapy

The role of erythropoietin in the "stroke belt" phenomenon

Global geographic disparities in stroke mortality rates are substantial. In the US alone, higher stroke mortality rates are reported in the Southeast part particularly along the coastline while lower rates have been observed in the Mountain region. The phenomenon has been called the "stroke belt". Although many theories have attempted to explain such nonrandom distribution of stroke mortality rates, no conclusive explanations have been drawn so far. I hypothesize that this nonrandom stroke distribution is related to regional differences in individual levels of erythropoietin (EPO), a hormone, which production depends on the tissue hypoxia due to variation in altitude. If successful, future studies based on this hypothesis may open up new avenues for treatment of such an important health issue as stroke. More importantly, future studies based on this theory may shed the lights on the mechanism of stroke as well as other diseases which have nonrandom geographic distribution not only in the US but also internationally.

Education-specific estimates of life expectancy and age-specific disability in the U.S. elderly population: 1982 to 1991

The authors used mortality data for 1982 to 1991 linked to survey records from the 1982, 1984, and 1989 National Long Term Care Surveys to calculate gender differences over age in mortality and functional status for high (8 or more years of schooling) and low (less than 8 years of schooling) education subgroups. Males and females with high education maintained better functioning at later ages than those with low education. The authors also found that mortality was higher, after conditioning on disability, in both the male and female low-education than the male and female high-education groups. The size of the education effect on both disability and mortality was large, for example, about 7.6 years difference in female life expectancy at age 65; a roughly 2-year difference for males.

Chronic disability trends in elderly United States populations: 1982-1994

Statistically significant declines in chronic disability prevalence rates were observed in the elderly United States population between the 1982 and 1989 National Long Term Care Surveys (NLTCS). The 1994 NLTCS was used to investigate whether disability rate declines continued to 1994. The 1982, 1984, 1989, and 1994 NLTCS employ the same sample design and instrumentation so that trends in disability can be estimated with minimal sampling and measurement bias. Age (5-year categories from 65 to >95)-specific rates were calculated for the 1982 NLTCS and applied to United States Census Bureau estimates of the 1994 population to calculate chronic disability prevalence rates adjusted for aging in the United States population aged > 65. The 1982 age standardized rates were compared with 1994 NLTCS estimates. The prevalence of disability estimated for 1994 (21.3%) was 3.6% lower than the 1982 age standardized rate (24.9%)-a highly significant reduction (t = -8.5; P << 0.0001). Of the 3.6 percentage point decline in prevalence, 1.7% occurred in the 5 years between 1989 and 1994-compared with the 1.9% decline in the 7 years between 1982 and 1989. Both declines are significant. Because of the shorter time period, the per year decline in disability prevalence from 1989 to 1994 was greater than that from 1982 to 1989. Given the higher acute and long-term care service needs of the disabled elderly population, Medicare, Medicaid, and private health expenditures may be dramatically lower than if declines had not occurred.

Predictors of stroke pattern in hypertensive patients

BACKGROUND AND PURPOSE

Hypertension is a recognized risk factor for stroke. However, it is not clear why hypertensive patients may have different types and causes of stroke.

METHODS

The possible role of coexisting factors was studied in 1057 patients with hypertension and first stroke admitted to a population-based stroke center. We used logistic regression analysis (multivariate and polychotomous) and the Lausanne Stroke Registry definitions of cerebral hemorrhage, cerebral infarction, lacunar infarction, cardioembolism and large artery disease.

RESULTS

Cerebral hemorrhage was not more frequent in these hypertensive patients (111/1057 = 10.5%) than in the total population of the registry (213/2145 = 10%). Cerebral infarction was associated with age above the median (69 years), diabetes, smoking history, family history of cardiac or cerebrovascular disease, hypercholesterolemia and previous TIA. In the ischemic group (n = 946), patients suffered from a lacunar infarction in 36% of the cases, large artery disease was present in 21% of them and cardioembolism in 14.5%. Large artery disease correlated with smoking history (odds ratio: 2.14; 95% confidence intervals: 1.55-2.95) and previous TIA (OR:1.96; 95% CI:1.39-2.75). Cardioembolism correlated with age over 69 years (OR:2.13; 95% CI:1.47-3.09). In patients with previous TIA and smoking history, large artery disease was presumed in 45% of the cases (vs 21%). Patients aged over 69, suffered a cardioembolic stroke in 29% of the cases (vs 14.5%). Lacunar infarction occurred in 49% of patients aged less than 70 years when no history of smoking or previous TIA was present (vs 36%).

CONCLUSION

The associations between hypertension, TIA, age and smoking history may partially explain why patients with hypertension are more likely to develop a cerebral hemorrhage, lacunar infarction, cardioembolic or a large artery disease stroke.