title: The choice of threshold limits for pediatric ambulatory blood pressure monitoring influences clinical decisions.
abstract: OBJECTIVE
  Hypertension in children may be defined by blood pressure elevated above the 95th percentile according to sex and age. Population data for ambulatory blood pressure provide different age-related and sex-related threshold limits to office-derived data. We sought to determine whether, when using ambulatory blood pressure monitoring in a clinical setting, changing 95th percentile threshold limit sets from office-derived to ambulatory blood pressure-derived would lead to different diagnostic decisions.
  
  
  METHODS
  Three nephrologists who were blinded as to patient identity and limit setting method reported on 42 ambulatory blood pressure records from a mixed group of patients aged 5-18 years by using both office-derived threshold limits for the 95th centile of blood pressure and ambulatory blood pressure-derived limits. Decisions regarding the presence or absence of hypertension were compared for each patient according to the limit set.
  
  
  RESULTS
  Thirty-five (83%) patients were considered to be hypertensive when office-derived threshold limits were used and 20% (P=0.005) fewer records were reported as showing hypertension when ambulatory blood pressure-derived threshold limits were used. When ambulatory blood pressure limits were applied, there were fewer records with an awake systolic blood pressure load >50% (P=0.004) and the average awake systolic blood pressure load was significantly lower (P<0.001).
  
  
  CONCLUSIONS
  Ambulatory blood pressure normative data tend to provide higher blood pressure limits for age and sex. Consequently, when ambulatory blood pressure data are used to set threshold limits, clinical decisions based on ambulatory blood pressure may be different than when office limits are used. These findings demonstrate the importance of using the most appropriate limit sets to analyze ambulatory blood pressure and when interpreting ambulatory blood pressure-based research.
authors.affiliation: Department of Nephrology, Sydney Children's Hospital, Randwick, New South Wales, Australia.
authors.forename: Sean E
authors.initials: SE
authors.lastname: Kennedy
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Mackie
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Craig
authors.forename: Gad
authors.initials: G
authors.lastname: Kainer
mesh_terms: D000293:Adolescent; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D002648:Child; D003657:Decision Making; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D010347:Patient Care Planning; D012016:Reference Values