Abstract
The definition of hypertension and the values of systolic and diastolic blood pressure (BP) that should be considered as therapeutic targets have changed over time and vary across scientific societies, which may generate uncertainty in the decision-making process among clinicians and patients. We traced the evolution and described the differences in all the 32 Clinical Practice Guidelines for the management of hypertension released by the following national and international scientific societies: World Health Organization-WHO; International Society of Hypertension-ISH; Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure-JNC; American Heart Association-AHA; American College of Cardiology-ACC; European Society of Cardiology-ESC; European Society of Hypertension-ESH; and UK National Institute for Health and Care Excellence-NICE. Throughout the decades, the BP values used for hypertension definition, treatment initiation, and targets to achieve started from SBP/DBP ≥ 160/95 mmHg, established at the end of the 70s, progressively decreased, and were differentiated by individual cardiovascular risk. In the last decade, a divergent approach emerged across scientific societies: while WHO/ISH and NICE recommended thresholds and targets for the general population at SBP/DBP < 140/90 mmHg, ESH/ESC and ACC/AHA guidelines further and markedly reduced both BP threshold values and therapeutic targets, recommending as ideal SBP/DBP values < 130/80 mmHg and encouraging an SBP < 120 mmHg. Discrepancies also emerged in the assessment of the quality of the evidence: although the methodological approaches largely improved over time and across all the institutions assessed, various degrees of incompleteness on the adopted scales were reported, and potentially conflicting situations emerged, particularly when weaker evidence was used to build strong recommendations. Although some degree of discrepancy among guidelines is expected, some of the differences are large and can lead to widely different approaches in the management of BP control. A standardization of the methodology and interpretation of the evidence supporting the guidelines may help to reduce the variability in order to provide the best possible guidance for clinical practice and patient health.