Changes in Ambulatory Blood Pressure Phenotype over Time in Children and Adolescents with Elevated Blood Pressures

Objective To determine the stability of ambulatory blood pressure monitoring (ABPM) over time in children referred for evaluation of elevated BPs and assess for factors predicting change. Study design This retrospective chart review conducted at Seattle Children's Hospital and University of Pittsburgh Medical Center Children's Hospital of Pittsburgh identified 124 children referred for elevated BPs with 2 ABPM studies at least 6 months apart. All subjects received lifestyle counseling. Subjects with secondary hypertension (HTN) or on antihypertensive medication were excluded. ABPM phenotype was classified using American Heart Association guidelines as showing normal BP, prehypertension, and HTN. Generalized linear mixed effect regression models were used to regress stable, improving, or worsening HTN outcomes at study follow-up on baseline BP index and load variables. Results The median age of patients was 14.1 years (73% males) and the median interval between studies was 18 months. ABPM phenotype changed in 58 of 124 children, with 16% worsening and 31% improving. Older age was associated with persistence of HTN. Although not significant, decrease in body mass index z-score tracked with sustained normal ambulatory BPs. Conclusions Although the sample size is small, our study suggests ABPM phenotype shows variability over time. Further study is required to identify factors supporting risk for progression of ABPM phenotype over time.