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1. To investigate whether morning blood pressure (MBP) can reflect levels of daytime and nocturnal blood pressure (BP) 2. To access the relationship between each period's BP (morning, daytime, nighttime and 24-hour, orderly) and subclinical target organ damage.
The authors recruited 1140 patients with essential hypertension in West China Hospital from January 2015 to December 2015. 24-hour ambulatory blood pressure monitoring, demographic data and relevant target organ damage index measurements were performed. Patients were divided into untreatment and treatment groups to discuss respectively. Pearson correlation analysis, Kappa consistency test, multiple linear regression, Logistic regression and AUC were used.
1. In untreatment group, the coefficients of consistency Kappa between MBP and daytime, nighttime, 24-hour BP were 0.775, 0.418, 0.643 (all P< 0.001) respectively; 0.743, 0.482, 0.677 (all P< 0.001) in treatment group. 2. By Pearson correlation analysis, in untreatment group, each period's SBP was positively correlated with UACR, LA, IVS, LVPW, and IMT (all P< 0.05), but no significant difference statistically in LVMI (P > 0.05). In treatment group, each period's SBP was positively correlated with UACR, IVS, LVPW, LVMI and IMT (all P< 0.05), but not in LA (P > 0.05). 3. By multiple linear regression and Logistic regression models, in untreatment group, the coefficients of regression β and odds ratio (OR) of each period's SBP and UACR, IMT had significant difference statistically (all P< 0.05), but not in LVMI (all P> 0.05). In treatment group, the coefficients of regression β and OR in UACR, IMT, LVMI had significant difference statistically (all P< 0.05). 4. In untreatment group, each period's SBP had significant difference statistically (AUC: 0.658, 0.686, 0.726, 0.704, respectively, all P< 0.01) in discriminating UACR, but not in IMT and left ventricular hypertrophy (all P> 0.05). In treatment group, each period's SBP had significant difference statistically (AUC: 0.676, 0.682, 0.726, 0.702, respectively, all P< 0.01) in discriminating UACR and left ventricular hypertrophy (AUC: 0.646, 0.683, 0.684, 0.687, respectively, all P< 0.01), but not in IMT (all P> 0.05). 5. Among population with controlled MBP, patients with uncontrolled nocturnal BP had higher IMT (0.83±0.17 vs 0.74±0.17, P=0.009), UACR (1.25±0.72 vs 0.92±0.58, P=0.005) than patients with controlled nocturnal BP. In 24-hour BP, the uncontrolled had higher UACR (1.29±0.72 vs 0.99±0.64, P=0.040) than the controlled. In daytime BP, target organ damage had no significant statistical difference between the uncontrolled and the controlled (all P>0.05).
MBP levels mainly reflected the daytime BP levels rather than nighttime BP. Each period's BP had impact on target organ damage, but organ target was not completely same. The association between MBP and target organ damage didn't show a distinct advantage over that of other periods' BP. But nocturnal BP had a special advantage of reflecting renal and vascular damage.