Prognostic significance of morning surge in blood pressure: which definition, which outcome?

The prognostic significance of morning surge in blood pressure (BP) remains obscure because the findings of the four prospective studies available [ambulatory BP monitoring (ABPM) substudy of the Syst-Eur trial, the Jichii Medical School ABPM-wave1 study, the Bordeaux hypertensive cohort study, and the Ohasama study] have generated conflicting results partly because of small number of events and differences in definitions, measurement conditions, target outcomes, and study populations. A large morning surge was associated with a significantly lower risk of total cardiovascular events in the Syst-Eur study. On the contrary, a large morning surge was associated with a significantly higher risk of total stroke events in the Jichii Medical School ABPM-wave1 study, and of total cardiovascular events in the Bordeaux hypertensive cohort study. The Ohasama study found that a large morning surge was not associated with the risk of total stroke events, but rather with a significantly higher risk of cerebral hemorrhage. More prospective studies or meta-analyses are required to better elucidate the prognostic significance of the morning surge in BP.