title: How reliable is isolated clinical hypertension defined by a single 24-h ambulatory blood pressure monitoring?
abstract: BACKGROUND
  Isolated clinical hypertension (ICH) is characterized by a persistently elevated clinic blood pressure in the presence of a normal day-time or 24-h ambulatory blood pressure (ABP). This definition is based on a single ABP monitoring (ABPM) and little attention has been focused on the reproducibility of this condition.
  
  
  OBJECTIVE
  To investigate the reliability of the criteria currently recommended by major hypertension guidelines to detect ICH based on a single 24-h ABPM session.
  
  
  METHODS
  A total of 611 never-treated grade 1 and 2 hypertensive patients (mean age 46 +/- 12 years) referred for the first time to our out-patient clinic, underwent repeated clinic blood pressure measurements, routine investigations, two 24-h periods of ABPM 1-4 weeks apart, cardiac and carotid ultrasound examinations. ABPM was always performed over a working day and the same daily activities were recommended during the two periods. ICH was diagnosed by the following criteria: (i) mean daytime values < 135/85 mmHg or (ii) mean 24-h blood pressure values < 125/80 mmHg during the first ABPM.
  
  
  RESULTS
  The overall prevalence of ICH was 7.1% according to criterion (i) and 5.4% according to criterion (ii). Twenty (46.6%) of the 43 patients with mean daytime blood pressure values < 135/85 mmHg during the first ABPM, exceeded this cut-off value during the second ABPM period. Twenty-two (66.6%) of the 33 patients with mean 24-h blood pressure values < 120/80 mmHg during the first ABPM did not confirm a normal blood pressure profile during the second ABPM recording. Cardiovascular involvement was significantly lower in subjects with persistent normal ABP compared to those with non-reproducible ICH pattern or sustained hypertensives.
  
  
  CONCLUSIONS
  These findings clearly indicate that: (i) the classification of ICH on the basis of a single ABPM, using the cut-offs suggested by major hypertension guidelines, has a limited short-term reproducibility and (ii) repeated ABPM recordings should be recommended to correctly diagnose patients with ICH and improve cardiovascular risk stratification.
authors.affiliation: Department of Clinical Medicine and Prevention, University of Milano-Bicocca, Milan, Italy. cesare.cuspidi@unimib.it
authors.forename: Cesare
authors.initials: C
authors.lastname: Cuspidi
authors.forename: Stefano
authors.initials: S
authors.lastname: Meani
authors.forename: Carla
authors.initials: C
authors.lastname: Sala
authors.forename: Cristiana
authors.initials: C
authors.lastname: Valerio
authors.forename: Veronica
authors.initials: V
authors.lastname: Fusi
authors.forename: Alberto
authors.initials: A
authors.lastname: Zanchetti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
mesh_terms: D000328:Adult; D000419:Albuminuria; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods / Q000706:statistics & numerical data*; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D004452:Echocardiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D015203:Reproducibility of Results