Nighttime blood pressure, systolic blood pressure variability, and left ventricular mass index in children with hypertension

Background Nighttime blood pressure (BP) and systolic BP variability on ambulatory blood pressure monitoring (ABPM) have been strongly associated with target-organ damage in hypertensive adults. The clinical relevance of these variables in children with hypertension remains under-studied. Methods The study group included children aged 5-18 years old referred to the outpatient nephrology clinic for an elevated casual BP who underwent an ABPM and echocardiography (ECHO) study and did not have secondary hypertension. The interpretation of ABPM parameters and left ventricular mass index (LVMI) was based on normative references. Results Seventy-two children fulfilled the inclusion criteria. The association of various potential predictors including age, BMI z-score, casual BP z-score and ABPM parameters (BP z-score, BP load, nocturnal dipping and BP variability-within-subject standard deviation (SD) of BP) with LVMI was analyzed. On adjusted regression analysis, nighttime systolic BP load [standardized regression coefficient (beta) 0.23; p<0.05] and daytime systolic BP variability (beta 0.37; p<0.05) had significant association with LVMI. Conclusions In children with primary hypertension, nighttime systolic BP load and daytime systolic BP variability had a stronger association with LVMI than casual BP and other ABPM parameters. Future longitudinal studies are needed to establish the causality among these variables.