关键词: 高血压, 诊断临界值, 循证医学

Abstract:

Hypertension is a clinical diagnosis and is defined as the level of blood pressure (BP) at which the benefits of treatment unequivocally outweigh the risks of treatment, as documented by randomized controlled trials (RCTs). According to the current Chinese hypertension guidelines, the office BP threshold for diagnosing hypertension is systolic BP (SBP) ≥140 mmHg and/or diastolic BP (DBP) ≥90 mmHg. However, in the 2017 ACC/AHA hypertension guidelines the diagnostic threshold for hypertension was reduced to ≥130/80 mmHg with purpose of promoting more intensive BP treatment. Some Chinese experts suggest to adopt this new standard, but many more point out that such a change will impact severely on our healthcare system. This paper will explain why the BP threshold should not be lowered down to 130/80 mmHg from an academic perspective.During the past several decades a large number of RCTs have shown that, in hypertensive patients with drug treatment, lowering SBP/DBP to <140/90 mmHg is associated with significant reductions in major cardiovascular (CV) events and all-cause mortality. In 2003 American hypertension guidelines (JNC 7) recommended to treat patients with diabetes or chronic kidney disease (CKD) to BP goal of <130/80 mmHg. However, European experts found that recommendation was not supported by RCT evidence. The 2014 evidence-based American guidelines (JNC 8) drew the same conclusion and recommended a BP goal of <140/90 mmHg for hypertensive persons young than 60 years, including those with diabetes or CKD. The six recently published RCTs showed different results. Lowering SBP to <130/80 mmHg in patients with recent lacunar stroke did not result in a significant reduction of recurrent stroke in the SPS3 trial. Targeting a SBP of <120 mmHg did not reduce the rate of major CV events in the ACCORD study. Both the HOPE-3 trial and the CHINOM trial showed that in low-to-moderate risk patients with a BP in the high-normal range, antihypertensive drug treatment was not associated with a lower rate of major CV events than placebo. The SPRINT trial and the STEP study showed that intensive treatment with a SBP target of <120 mmHg or <130 mmHg resulted in a lower incidence of CV events. SPRINT trial was the major driver for the BP threshold changes introduced in the 2017 ACC/AHA guidelines. However, in the SPRINT trial a unique unattended BP measurement method was used that was different from methods used in previous studies. The SBP levels, when assessed by the unattended method, are usually much lower than when measured with conventional office BP measurement. Both the SPRINT trial and the STEP study are open-labelled and stopped early that typically provide exaggerated estimates of benefits. Both the studies required that patients in the standard treatment group stop taking antihypertensive drugs or have the doses reduced if their SBP dropped to below the lower limit of the target range. Reduction of therapy is not in line with clinical practice and would seem to bias the trial against the standard treatment. Thus, there still lacks high-quality evidence to convince us to reset the diagnostic threshold for hypertension to 130/80 mmHg, down from the current trigger of 140/90.

Key words: Hypertension, Diagnostic Threshold, Evidence-based medicine