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Relation between blood pressure and stroke mortality
A J Palmer1, C J Bulpitt, A E Fletcher
1Hammersmith Hospital, London, England.
Insights
High blood pressure significantly increases stroke mortality risk in hypertensive patients. Even small increases in systolic and diastolic blood pressure, both treated and untreated, are linked to higher stroke death rates.
Area of Science:
- Cardiovascular Medicine
- Epidemiology
- Hypertension Research
Background:
- Hypertension is a major risk factor for stroke mortality.
- Understanding the precise relationship between blood pressure levels and stroke death is crucial for public health.
- Longitudinal studies are essential to establish causal links and quantify risks.
Purpose of the Study:
- To investigate the association between untreated and treated blood pressure levels and stroke mortality in a large cohort of hypertensive patients.
- To quantify the increased risk of stroke death per unit increase in systolic and diastolic blood pressure.
- To examine potential differences in this relationship based on age and sex.
Main Methods:
- Analysis of data from 10,186 hypertensive patients followed for an average of 9 years.
- Inclusion of both untreated and treated blood pressure measurements.
- Age-adjusted statistical analysis to determine relative hazard rates for stroke mortality.
Main Results:
- A 1 mm Hg increase in untreated systolic blood pressure correlated with a 1% increase in stroke mortality risk for both men and women.
- Untreated diastolic blood pressure increases showed a ~3% risk increase in men and 1% in women per 1 mm Hg.
- Treated systolic and diastolic blood pressure increases were associated with 2% and 3% higher stroke mortality, respectively, per 1 mm Hg.
Conclusions:
- Elevated blood pressure, whether treated or untreated, is a significant predictor of stroke mortality in hypertensive individuals.
- The risk of stroke death increases consistently with higher blood pressure readings.
- While age and treatment status modify the risk slightly, the overall association between blood pressure and stroke mortality remains robust.
Abstract:
The relation between stroke mortality and blood pressure was investigated in 10,186 hypertensive patients followed up in the Department of Health Hypertension Care Computing Project for an average of 9 years. An untreated blood pressure measurement was available in 3,472 men and 3,405 women. The age-adjusted risk of stroke death increased by 1% for every 1 mm Hg increase in untreated systolic blood pressure. The relative hazard rate was 1.014 (95% confidence interval [CI], 1.007, 1.021) in men and 1.009 (1.003, 1.016) in women. The corresponding increases for 1 mm Hg for untreated diastolic blood pressure were almost 3% in men and again 1% in women (relative hazard rate 1.026 [95% CI, 1.014, 1.038] in men and 1.010 [1.000, 1.021] in women). Treated blood pressure measurements were available in 3,073 men and 3,148 women. Stroke mortality increased by 2% for a 1 mm Hg increase in treated systolic pressure and 3% for the corresponding increase in diastolic blood pressure. The relation between stroke mortality and blood pressure was similar over and under the age of 65, although the increase in mortality with pressure was greater for treated diastolic blood pressure in women under the age of 65 than over this age. There was no evidence for a J-shaped relation between stroke mortality and either systolic or diastolic pressure in men. In women there was a suggestion of such a relation, but since this relation was also observed for untreated pressures, any increase in risk at lower pressures is unlikely to be a result of treatment.