Disturbed circadian blood pressure rhythm and C-reactive protein in essential hypertension

We investigated the effect of the diverse definition criteria of the dipping and non-dipping status on the assessed differences in inflammatory activation between dippers and non-dippers with essential hypertension. 269 consecutive subjects (188 males, aged 50 +/- 7 years) with untreated stage I-II essential hypertension underwent ambulatory blood pressure (BP) monitoring and high-sensitivity C-reactive protein (hs-CRP) level determination. The population was classified into dippers and non-dippers based on the three following different definitions: true non-dippers (TND): non-dippers (nocturnal fall of systolic and diastolic BP of <10% of the daytime values, n = 95) and dippers (the remaining subjects, n = 174); true dippers and true non-dippers (TD-TND): non-dippers (nocturnal fall of systolic and diastolic BP<10%, n = 95) and dippers (nocturnal fall of systolic and diastolic BP >= 10%, n=75); systolic non-dippers (SND): non-dippers (nocturnal systolic BP fall of <10% of the daytime values, n = 145) and dippers (the remaining subjects, n = 124). Non-dippers compared to dippers in the TND, TD-TND and SND classification exhibited higher levels of log hs-CRP (by 0.11 mg l(-1), P = 0.02; 0.13 mg l(-1), P=0.03 and 0.14 mg l(-1), P = 0.02, respectively) and 24 h pulse pressure (PP) (by 4 mm Hg, P = 0.006; by 5 mm Hg, P = 0.003 and by 5 mm Hg, P<0.0001, respectively). Twenty-four hour PP and nocturnal systolic BP fall were independent predictors of log hs-CRP (P<0.05 for both) in multiple regression analysis. In conclusion, essential hypertensive non-dippers compared to dippers exhibit higher hs-CRP values, irrespective of the dipping status definition. Furthermore, ambulatory PP and nocturnal systolic BP fall interrelate and participate in the inflammatory processes that accompany non-dipping state.