Background and PurposeTreatment of hypertension effectively reduces the risk of stroke. However, many treated patients still have high blood pressure (BP), other cardiovascular risk factors, and complications. The risk of stroke in treated hypertensive patients is not well understood.MethodsWe analyzed the level of BP over 1 year before the onset of stroke and other cardiovascular risk factors in treated hypertensive patients in a case-control study. The study population included 126 hypertensive patients (74 men; mean age, 70.9 years) with first strokes during 1988–1993 who had been treated for >1 year before stroke onset (stroke group). As a control group, we selected 126 sex- and age-matched hypertensive patients who were treated during the same period and were free from stroke.ResultsMean 12-month BP was not significantly different between stroke and control groups, although systolic BP was 2.5 mm Hg higher in the stroke group (148.7 [95% CI, 146.1 to 151.3]/82.1 [95% CI, 80.5 to 83.7] versus 146.2 [95% CI, 143.8 to 148.6]/82.4 [95% CI, 81.0 to 83.8] mm Hg). In patients aged <70 years, mean systolic BP was significantly higher in the stroke group than the control group (150.5 [146.3 to 154.7] versus 144.0 (140.6 to 147.4) mm Hg). Mean pulse pressure was also significantly higher in the stroke group than the control group in patients aged <70 years but not in older patients. In the stroke group, the level of BP within 1 month before stroke onset did not differ from the mean value over the 12-month period. Patients with brain hemorrhage had higher diastolic BP than those with other subtypes. The stroke group had higher plasma glucose, lower HDL cholesterol, and higher frequencies of diabetes mellitus, proteinuria, atrial fibrillation (29.4% versus 4.0%), and use of antiplatelet (31.0% versus 11.1%) and anticoagulant (10.3% versus 1.6%) agents than the control group.ConclusionsThe onset of stroke in treated hypertensive patients was related to a higher level of BP in subjects <70 years old, although this relationship was not obvious in older patients. The risk of stroke in these patients was associated with the presence of metabolic risk factors and cardiovascular complications. Office BP did not change significantly 1 month before the onset of stroke.