Altered assessment of antihypertensive effectiveness in hypertensive (HTN) children using ambulatory blood pressure (abp) compared to casual blood pressure (CBP) measurements

Abstract

ABP monitoring (ABPM) is an effective tool for the diagnosis of HTN and predicts end organ damage in HTN children. In adults ABPM is also valuable in assessing antihypertensive efficacy. To determine if variations exist in the assessment of response to a antihypertensive drug (felodipine ER) in HTN children by ABP compared to CBP. A diagnosis of HTN was made if CBP exceeded the 95th%ile for age, gender and height based on Task Force data. Patients were eligible for this study if ABPM was performed before receiving study drug. Following completion of the felodipine ER double-blind phase (Peds Nephrol, under review), pts entered an open-label phase and were given an investigator-determined dose to achieve CBP control. ABPM was performed after 2 and 4 months of treatment; these results were not used for dose adjustment. 24-hr ABPM was performed with SpaceLabs 90217 oscillometric monitor with readings q20 min with appropriately-sized cuffs. Pts were classified as responder (R) if the BP fell by ≥5 mmHg for SBP; ≥3 mmHg for DBP for either CBP or 24 hr mean ABP readings. Non-responders (NR) did not achieve this level of BP reduction. CBP measurements were trough values. Of 17 children treated with felodipine ER, 11 pts (12yo,10 males, 5 white, 3AA, 3 Hispanic) were enrolled in this study. The mean Felodipine ER dose was 0.1 mg/kg at both 2 and 4 mos. At 2 mos, the two techniques were congruent in the identification of R pts for SBP in 55% and DBP in 45% of subjects. Among R, the mean decline in BP determined by CBP was 12.6/12.5 mm Hg. In contrast, the mean BP fall was only 3.4/1.2 mm Hg by ABP (P<0.003). Similar values were seen at 4 mos (P<0.004). Evaluation of drug effects using ABP led to different results compared to CBP in absolute BP reduction, numbers of responders, and those classified as persistently HTN. This suggests that ABPM yields important information and should be included in antihypertensive trials in children (see Table 1). Response to Felodipine ER by ABP and CBP P = 0.06 vs CBP p < .01 vs CBP Response to Felodipine ER by ABP and CBP P = 0.06 vs CBP p < .01 vs CBP