U-shaped relationship between mortality and admission blood pressure in patients with acute stroke.

OBJECTIVE

To evaluate the relationship between systolic blood pressure (SBP) or diastolic blood pressure (DBP) on admission and early or late mortality in patients with acute stroke.

DESIGN

Prospective study of hospitalized first-ever stroke patients over 8 years.

SETTING

Stroke unit and medical wards in a University hospital.

SUBJECTS

A total of 1121 patients admitted within 24 h from stroke onset and followed up for 12 months.

MAIN OUTCOME MEASURES

Mortality at 1 and 12 months after stroke in relation to admission SBP and DBP.

RESULTS

Early and late mortality in patients with acute ischaemic or haemorrhagic stroke in relation to admission SBP and DBP followed a 'U-curve pattern'. After adjusting for known outcome predictors, the relative risk of 1-month and 1-year mortality associated with a 10-mmHg SBP increase above 130 mmHg (U-point of the curve) increased by 10.2% (95% CI: 4.2-16.6%) and 7.2% (95% CI: 2.2-12.3%), respectively. For every 10 mmHg SBP decrease, below the U-point, the relative risk of 1-month and 1-year mortality rose by 28.2% (95% CI: 8.6-51.3%) and 17.5% (95% CI: 3.1-34.0%), respectively. Low admission SBP-values were associated with heart failure (P < 0.001) and coronary artery disease (P = 0.006), whilst high values were associated with history of hypertension (P < 0.001) and lacunar stroke (P < 0.001). Death due to cerebral oedema was significantly (P = 0.005) more frequent in patients with high admission SBP-values, whereas death due to cardiovascular disease was more frequent (P = 0.004) in patients with low admission SBP-values.

CONCLUSION

Acute ischaemic or haemorrhagic stroke patients with high and low admission BP-values have a higher early and late mortality. Coincidence of heart disease is associated with low initial BP-values. Death due to neurological damage from brain oedema is associated with high initial BP-values.