Dipping pattern of nocturnal blood pressure in patients with hypertension.

Four dipping categories have been described, based on the night-day blood pressure ratio from 24-h ambulatory blood pressure recordings: extreme dippers (night-day blood pressure ratio < or = 0.8), dippers (0.8 < ratio < or = 0.9), nondippers (0.9 < ratio < or = 1.0) and reverse dippers (ratio > 1.0). The main purpose of this article is to discuss the prognostic significance of these four dipping categories in hypertension, mainly based on a large meta-analysis of individual patient data. In hypertensive patients without cardiovascular disease at baseline and with statistical adjustment for confounders and 24-h blood pressure, mortality was lower in extreme dippers than in dippers, whereas the incidence of cardiovascular events was higher in reverse dippers. The worst prognosis for reverse dippers was also observed in hypertensive patients with major cardiovascular disease at baseline. Higher incidences of cardiovascular events and mortality were also found in reverse dippers in comparison with dippers in a comprehensive meta-analysis of population-based studies but outcome was not significantly different between extreme dippers and dippers. Based on these findings, there appears to be little doubt that reverse dipping is associated with a worse prognosis. Some studies suggest that prognosis is similar in nondippers and extreme dippers in comparison with dippers, but other studies suggest a somewhat worse prognosis in nondippers, or a better or worse prognosis in extreme dippers.