Jackson R
Department of Community Health, School of Medicine, University of Auckland, New Zealand.
J Hum Hypertens. 1995 Jul;9 Suppl 2:S25-8.
Epidemiological data suggest that the lower the BP, the lower the cardiovascular risk. This is true across a broad range of BP levels, including those considered 'normal'; more than half of all cardiovascular events attributed to raised BP occur when DBP is < or = 95 mmHg. The belief that lowering BP too far is harmful is based on the hypothesis of a J-shaped relationship between BP and risk of cardiovascular disease. The weight of evidence now clearly suggests, however, that the J-shaped curve is not a consequence of treatment, but of underlying cardiovascular dysfunction that reduces BP and increases morbidity and mortality. Current prospective observational data give no evidence of a threshold BP below which there is no further reduction in cardiovascular disease risk. The average BP reductions in randomised trials are 5-6 mmHg (diastolic) and 10-12 mmHg (systolic), which would be expected to reduce the incidence of stroke by 35% and of coronary heart disease by 21%. If average BP reductions were doubled, prospective observational studies suggest the cardiovascular risk would be reduced by a further 15-20%.
流行病学数据表明，血压越低，心血管风险越低。在广泛的血压水平范围内都是如此，包括那些被认为“正常”的血压水平；舒张压小于或等于95 mmHg时，超过一半的心血管事件归因于血压升高。认为将血压降得过低有害这一观点是基于血压与心血管疾病风险之间呈J形关系的假设。然而，目前的证据明确表明，J形曲线不是治疗的结果，而是潜在的心血管功能障碍的结果，这种功能障碍会降低血压并增加发病率和死亡率。目前的前瞻性观察数据没有证据表明存在一个血压阈值，低于该阈值心血管疾病风险就不会进一步降低。随机试验中血压的平均降幅为舒张压5 - 6 mmHg和收缩压10 - 12 mmHg，预计这将使中风发病率降低百分之三十五，冠心病发病率降低百分之二十一。如果平均血压降幅翻倍，前瞻性观察研究表明心血管风险将进一步降低百分之十五至二十。
