Table 2. Comparison of expected and observed effects of a 7.5-mmHg systolic blood pressure difference on coronary heart disease, stroke, and heart failure.

Relative Risk Reduction	CHD	Stroke
Expecteda from cohort studies	19%	27%
Observeda in trials of BP lowering versus control	17%	33%
Observed in trials of more versus less BP lowering	13%	24%

^aThe associations observed in cohort studies [2] and the reductions shown in trials of BP lowering versus control [4] are shown, standardized to the 7.5-mmHg systolic difference seen in the current meta-analysis (e.g., previous trials showed a RR for stroke of 0.59 with a 10 mmHg systolic reduction, so one would expect a 33% reduction for 7.5 mmHg lower systolic, as 0.59^7.5/10 = 0.67).