有很多原因。首先,血压变异性有很多种类型,比如,24小时内的血压变异性。血压在白天和夜间都是有很大变异的。在夜间,血压普遍偏低但是除此之外在24小时内还有极短期持久峰或长时持久峰。
《国际循环》:最近有研究对一些大规模试验的动态血压组的数据进行分析,结果显示一些时候动态血压组的患者为血压正常者,但是这些试验依然显示出这些患者的获益。
Dr Mancia: 这还没有证据,因为在试验中动态血压还没有被系统性使用而只是在小的亚组中被使用。我们公布了HOT、VALUE、ELSA 和ONTARGET(还没有发表)试验中的数据,但是只在很小样本量的亚组中发现使用动态血压,几千例患者中只有几百例患者,所以还不能根据这些数据得出结论。你能从中得出血压降低的结论但不能得出它们与临床意义和事件之间的结论。我们已知动态血压比临床血压低,但是我们的指南中用的是临床血压因为试验中用到的是临床血压值。正常情况下,我们所做的是试验开始时设定入选条件,符合入选条件的人被认为是试验结果的候选人。这也适用于白大衣高血压。没有排除这些患者的条件。如果有试验对白大衣高血压患者进行研究将是非常好的事情,但是从来没有人这么做因为有很多组织方面的原因限制了动态血压的大规模试验。
International Circulation: Recently there has been talk about trials where they have looked at ambulatory blood pressure cohorts from certain larger trials that showed that sometimes the ambulatory blood pressure cohort was normotensive but that these trials still showed a benefit in events.
Dr Mancia: There is no evidence of this kind because in trials, this has not been used systematically and only in small subgroups. We published data from HOT, VALUE, ELSA and ONTARGET (not yet published) but this is seen in very small subgroups, a few hundred patients out of several thousand, so you cannot reach a conclusion. You can reach a conclusion about the fall in blood pressure but not about the clinical significance in relation to events. We already know that ambulatory blood pressure is less than clinic blood pressure, but our guide has to be clinic blood pressure because this is what has been used in trials. Normally, what we do is when there is a trial and you have the entry criteria, people who fit into the entry criteria are considered as candidates to the results of the trial. This applies to white coat hypertension as well. There is no reason to exclude them. It would be nice to have a trial on white coat hypertensive patients but it has never been done because it is very difficult to have a major trial on ambulatory blood pressure for many organizational reasons.