Objective: Obesity in childhood is a profound risk factor for hypertension, and weight loss has positive effects on blood pressure (BP). However, the expected effect size on BP from weight reduction in children with obesity is insufficiently described. Therefore, the aim was to investigate the association between changes of degree of obesity and BP levels.
Subjects: This prospective cohort study examined subjects receiving behavioral lifestyle modification treatment who were registered in the Swedish national registry for treatment of childhood obesity (BORIS). A total of 5279 obese subjects (51.3% boys) had repeated BP measurements. The average follow-up time was 32 months. Degree of obesity was expressed as BMI standard deviation score (SDS) and BP as BP SDS.
Results: The mean age at treatment initiation was 10.3 years. The prevalence of hypertensive BP was 15.3% for systolic and 5.5% for diastolic pressure. Both systolic and diastolic BP SDS decreased when a lower BMI SDS was achieved; systolic BP SDS decreased 0.41 [0.33-0.49] and diastolic BP SDS decreased 0.26 [0.20-0.32] per BMI SDS unit reduction. The impact of BMI SDS reduction on BP SDS was greater in subjects with hypertensive levels at treatment initiation, but behavioral modification was an insufficient treatment for 27% of them. Obesity treatment failure increased the risk of developing hypertensive levels; HR = 1.81 [1.38-2.37] (systolic BP) HR = 3.82 [2.34-6.24] (diastolic BP), per unit increase in BMI SDS.
Conclusions: Weight loss is a key factor for hypertension prevention and treatment in children with obesity. However, its limited effect suggests that additional pharmacological antihypertensive treatment more readily should be considered.