The paradigm has shifted to systolic blood pressure

Abstract

Since the middle of the 20th century, most physicians and epidemiologists assessed the risks associated with hypertension based on the level of diastolic blood pressure (DBP). In a classic paper in 1971, the Framingham Heart Study clearly showed that systolic BP more accurately described the risk of all the complications we attribute to hypertension. It took 22 years until JNC V in 1993 also used systolic blood pressure (SBP) to define hypertension in US national guidelines. Since then, the paradigm has shifted dramatically. In JNC VI (1997) and JNC VII (2003), SBP has become the primary focus of risk stratification and treatment goals. This shift is a result of the Framingham results being confirmed by many others analyses, the most compelling of which is the recently published report of the Prospective Collaborative Study Group, which pooled 61 observational studies in more than 1 million volunteers with a collective experience of more than 12 million person-years. This group showed that the SBP level at baseline was a significantly more informative reading than DBP for predicting strokes and coronary heart disease (CHD). Furthermore, three trials of older individuals with isolated systolic hypertension, SHEP, SYST-Eur, and SYST-China, unambiguously demonstrated that effective antihypertensive therapy lowered the rate of strokes, heart failure, CHD, and even all-cause mortality. Finally, the World Health Organization (WHO)/International Society of Hypertension (ISH) Hypertension Trialists also showed that the level of SBP achieved in clinical trials comparing different antihypertensives with placebo and with each other was the strongest determinant of how effectively strokes and CHD events were reduced, although a similar relationship was not evident for heart failure. A recent metaregression analysis using new trials, many of which were used by the Trialists, and older studies not included in their analysis also showed that small differences in SBP can have a dramatic impact on cardiovascular outcomes. If there is one thing we have learned in the recent past, it is the need for us to focus on lowering SBP and getting it down to a reasonable goal. We have also learned that to do so, we will need to combine a variety of lifestyle and pharmacological approaches, always with combinations of drugs that will usually contain a low-dose thiazide-type diuretic with other antihypertensives.