What are the implications for the community of the discrepancy between the theory and practice of BP control?

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%.