Hypertension Control

There are very few studies which have documented that treatment of hypertension will decrease the risk of stroke occurrence after TIA or stroke recurrence after minor stroke. Numerous prospective studies and clinical trials, however, have consistently shown a decreased risk of stroke with control of mild, moderate, and severe hypertension in all age groups of stroke-free subjects. A meta-analysis of 9 prospective studies including 420,000 individuals followed for 10 years found that stroke risk increased by 46% for every 7.5mm Hg increase in diastolic blood pressure. This analysis disclosed a graded relationship with no low threshold. A subsequent meta-analysis of 14 treatment trials including 37,000 unconfounded randomized individuals followed for a mean of 5 years confirmed the expected reduced stroke risk. The analysis showed a mean diastolic reduction of 5-6mm Hg with a corresponding 35-40% reduction in stroke incidence. This reduced risk was identified regardless of the level of the index diastolic pressure. The authors here concluded that antihypertensive therapy should be prescribed for all moderate hypertensives with high stroke risk. Even a slight improvement in the control of hypertension could translate into a substantial reduction in stroke frequency.

In addition to the above meta-analysis, individual trials have also made significant contributions to our knowledge of the relationship between hypertension control and stroke risk. The STOP-Hypertension program (Swedish Trial in Old Patients with Hypertension) followed 1,627 randomized hypertensive patients aged 70 to 84 years for an average 25 months. This study indicated the benefit of managing hypertension in the elderly, finding a significant decline in stroke morbidity and mortality, as well as in total mortality. The SHEP (Systolic Hypertension in the Elderly Program) trial randomized 4,736 individuals over age 60 with isolated systolic hypertension (SBP > 160ram Hg with DBP < 90mm Hg) and followed for 4.5 years. The resulting 36% reduction in total stroke incidence confirmed the significance of managing isolated systolic hypertension, a condition affecting two-thirds of elderly hypertensives. In absolute terms, these two trials indicated that treating only 10-20 patients for five years will prevent one major cardiovascular event. From this data, we can infer that the proper control of hypertension after a TIA or stroke will confer a reduced stroke risk.

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