Effect of changes in BMI and waist circumference on ambulatory blood pressure in obese children and adolescents.

Abstract

Weight reduction has been accompanied with a reduction in clinic blood pressure (BP) in children and adolescents; however, the effect on ambulatory BP (ABP) is uncertain. The objective was to investigate the impact of weight changes on ABP in obese children and adolescents. Sixty-one severely obese patients aged 10-18 years underwent lifestyle intervention at the Children's Obesity Clinic. Patients were examined with ABP monitoring at baseline and after 1 year of treatment (follow-up). To account for growth, BP and BMI were standardized into z scores, whereas waist circumference was indexed by height [waist/height ratio (WHR)]. Patients experienced a reduction at follow-up in the degree of obesity [ΔBMI z score: -0.21, 95% confidence interval (CI) -0.32 to -0.10, P = 0.0003; and ΔWHR: -0.02, 95% CI -0.03 to -0.004, P = 0.009]. Δ24-h, Δdaytime and Δnight-time SBP and DBP in mmHg and changes in equivalent z scores were related to ΔBMI z scores and ΔWHR. These relationships were reproduced in multiple regression analyses adjusted for relevant confounders, for example, a reduction in one BMI z score corresponds to a reduction in 24-h SBP by 6.5 mmHg (P < 0.05). No relationship was found between changes in these anthropometric obesity measures and changes in clinic BP. Changes in obesity measures were closely related to changes in ABP, but not to changes in clinic BP, in severe obese children and adolescents after 1 year of lifestyle intervention. The findings emphasize the use of 24-h ABP measurements in children and adolescents.