P-613: Use of task force criteria to interpret pediatric ambulatory blood pressure may result in overdiagnosis of hypertension

Abstract

The interpretation of ambulatory BP (ABP) data in children is complicated by uncertainty over whether ambulatory hypertension should be defined using 95^th percentile BP limits from the Task Force Report on High Blood Pressure in Children and Adolescents (TF) or normative pediatric ABP datasets (Soergel et al, J. Peds. 1997;130:178-84). To determine how the choice of 95^th percentile BP limit affects the diagnosis of hypertension and the calculation of BP load, interpretations of ABP data from the same 24-hour period were compared using the two different limit sources in 152 children undergoing evaluation for persistently elevated clinic BP. Since the TF report includes no nighttime data and therefore provides no nighttime BP limits, hypertension for this analysis was defined as mean daytime BP greater than either: 1) the TF 95^th percentile based on gender, age, and height percentile, or 2) the daytime 95^th percentile from normative pediatric ABP data based on gender and height. BP load was calculated as the percentage of daytime BP readings exceeding the 95^th percentile from each of the two limit sources. ABPM was performed using Spacelabs oscillometric monitors (Spaeclabs Inc., Redmond, WA) programmed to measure BP every 20 minutes. Patient demographics showed a mean age of 12.6±3.2 yrs, 66% male, and 40% white / 29% AA / 26% Hisp. For the daytime period, the number of successful readings was 38.2±9, mean SBP was 129.6±12.4 mmHg, and mean DBP was 75.8±8.7 mmHg. Pair-wise t-test comparing the 95^th percentile BP limit from the two limit sources showed that patient-specific TF limits were lower than the patient-specific daytime ABP limits (p<0.001) for SBP (125 vs. 131 mmHg) and DBP (82 vs. 85 mmHg). Correspondingly, the prevalence of ambulatory hypertension (systolic and/or diastolic) was higher by TF criteria than by ABP criteria (66% vs. 42%; p<0.001). Among pts diagnosed as hypertensive by TF criteria, 36% (36/100) were normotensive by ABP criteria. Daytime BP load was also higher by TF criteria than by ABP criteria for SBP (58% vs. 43%) and DBP (31% vs. 23%)(p<0.001). These analyses suggest that the use of the lower TF limits that are derived solely from resting BP measurements may overdiagnose hypertension in ambulatory children. However, the most appropriate definition of ambulatory hypertension in children will remain uncertain until either set of limits is validated by association with or prediction of cardiovascular morbidity.

Child, Hypertension, Ambulatory Blood Pressure Monitoring