title: Importance of Calibration Method in Central Blood Pressure for Cardiac Structural Abnormalities.
abstract: Central blood pressure (CBP) independently predicts cardiovascular risk, but calibration methods may affect accuracy of central systolic blood pressure (CSBP). Standard central systolic blood pressure (Stan-CSBP) from peripheral waveforms is usually derived with calibration using brachial SBP and diastolic BP (DBP). However, calibration using oscillometric mean arterial pressure (MAP) and DBP (MAP-CSBP) is purported to provide more accurate representation of true invasive CSBP. This study sought to determine which derived CSBP could more accurately discriminate cardiac structural abnormalities.
  
  
  
  A total of 349 community-based patients with risk factors (71±5years, 161 males) had CSBP measured by brachial oscillometry (Mobil-O-Graph, IEM GmbH, Stolberg, Germany) using 2 calibration methods: MAP-CSBP and Stan-CSBP. Left ventricular hypertrophy (LVH) and left atrial dilatation (LAD) were measured based on standard guidelines.
  
  
  
  MAP-CSBP was higher than Stan-CSBP (149±20 vs. 128±15mm Hg, P < 0.0001). Although they were modestly correlated (rho = 0.74, P < 0.001), the Bland-Altman plot demonstrated a large bias (21mm Hg) and limits of agreement (24mm Hg). In receiver operating characteristic (ROC) curve analyses, MAP-CSBP significantly better discriminated LVH compared with Stan-CSBP (area under the curve (AUC) 0.66 vs. 0.59, P = 0.0063) and brachial SBP (0.62, P = 0.027). Continuous net reclassification improvement (NRI) (P < 0.001) and integrated discrimination improvement (IDI) (P < 0.001) corroborated superior discrimination of LVH by MAP-CSBP. Similarly, MAP-CSBP better distinguished LAD than Stan-CSBP (AUC 0.63 vs. 0.56, P = 0.005) and conventional brachial SBP (0.58, P = 0.006), whereas Stan-CSBP provided no better discrimination than conventional brachial BP (P = 0.09).
  
  
  
  CSBP is calibration dependent and when oscillometric MAP and DBP are used, the derived CSBP is a better discriminator for cardiac structural abnormalities.
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia. Kazuaki.Negishi@utas.edu.au.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Negishi
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Nolan
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Negishi
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Faraz
authors.initials: F
authors.lastname: Pathan
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Marwick
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: James E
authors.initials: JE
authors.lastname: Sharman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D001795:Blood Pressure Determination; D002138:Calibration; D005260:Female; D006325:Heart Atria / Q000473:pathology; D006333:Heart Failure / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D017379:Hypertrophy, Left Ventricular; D008297:Male
keywords: blood pressure determinations; blood vessels; cardiovascular diagnostic technique; heart function tests; hypertension; pulse wave analysis.