Night-day blood pressure ratio and dipping pattern as predictors of death and cardiovascular events in hypertension

Our objective was to assess the prognostic significance of the night-time dipping pattern and the night-day blood pressure (BP) ratio for mortality and cardiovascular events in hypertensive patients without major cardiovascular disease at baseline. We performed a meta-analysis on individual data of 3468 patients from four prospective studies performed in Europe. Age of the subjects averaged 61 +/- 13 years; 45% were men and 61% were under antihypertensive treatment at the time of ambulatory BP monitoring. The night-day BP ratio and 24-h BP averaged, respectively, 0.907 +/- 0.085/0.866 +/- 0.095 and 138.1 +/- 16.4/82.3 +/- 11.0mmHg. Total follow-up time amounted to 23 164 patient-years. We used multivariable Cox regression analysis to assess the outcome of reverse dippers, non-dippers and extreme dippers vs dippers, and to assess the hazard ratios associated with 1 standard deviation higher night-day BP ratio. In comparison with dippers, and with adjustment for confounders and 24-h BP, the incidence of cardiovascular events was worse in reverse dippers (P <= 0.05), whereas mortality was lower in extreme dippers (P <= 0.01); outcome was similar in non-dippers and dippers. The systolic night-day BP ratio independently predicted all-cause mortality and cardiovascular events (P <= 0.001), which persisted after additional adjustment for 24-h BP (P <= 0.05); appropriate interaction terms indicated that the results were similar in men and women, in younger and older patients and in treated and untreated patients. In conclusion, the dipping pattern and the night-day BP ratio significantly and independently predict mortality and cardiovascular events in hypertensive patients without history of major cardiovascular disease, even after adjustment for 24-h BP. Journal of Human Hypertension (2009) 23, 645-653; doi:10.1038/jhh.2009.9; published online 19 February 2009