title: Validation of the Withings BP-800 in pregnancy and impact of maternal characteristics on the accuracy of blood pressure measurement.
abstract: OBJECTIVE
  Firstly, to validate the Withings BP-800 automated device for use in pregnancy and, secondly, to assess the impact of maternal somatometric and demographic variables on the accuracy of the device.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Kings College Hospital, London, UK.
  
  
  METHODS
  Forty-seven women of any gestation.
  
  
  METHODS
  Validation: The British Hypertension Society (BHS) Protocol (1993) was used for the validation of the Withings BP-800. Two trained observers took nine sequential same arm measurements alternating between the Withings BP-800 and the mercury sphygmomanometer. Assessment of factors affecting the disagreement between the two devices: The associations between discrepancies in the measured systolic and diastolic blood pressure by the two devices and potential predictors of discrepancy and/or possible confounders of associations including age, gestational age, ethnicity, body mass index and arm circumference were investigated using two-level mixed effects models to take into account the repeated measurements.
  
  
  METHODS
  Accuracy of the Withings BP-800 based on the grading criteria of the BHS Protocol (1993).
  
  
  RESULTS
  The Withings BP-800 failed to meet the validation criteria of the BHS protocol for pregnancy and preeclampsia. Inter-device discrepancy was significantly associated with larger arm circumferences and was more pronounced with diastolic blood pressure. This relationship was independent of other maternal characteristics.
  
  
  CONCLUSIONS
  The Withings BP-800 cannot be recommended for the measurement of blood pressure in pregnancy or preeclampsia. The inaccuracy of the Withings BP-800 increases when used in patients with larger arm circumferences with a propensity to over-read.
authors.affiliation: Antenatal Hypertension Clinic, Division of Women's Health, Kings College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Hay
authors.affiliation: Senior Lecturer in Medical Statistics, Division of Health and Social Care Research, Kings College London, Addison House, Guy's Campus, London SE1 1UL, UK.
authors.forename: Salma
authors.initials: S
authors.lastname: Ayis
authors.affiliation: Antenatal Hypertension Clinic, Division of Women's Health, Kings College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK.
authors.forename: Diane
authors.initials: D
authors.lastname: Nzelu
authors.affiliation: Antenatal Hypertension Clinic, Division of Women's Health, Kings College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK.
authors.forename: Lauren
authors.initials: L
authors.lastname: James
authors.affiliation: Antenatal Hypertension Clinic, Division of Women's Health, Kings College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK; Harris Birthright Research Centre for Fetal Medicine, Division of Women's Health, Kings College Hospital, Denmark Hill, London SE5 9RS, UK. Electronic address: nick.kametas@kcl.ac.uk.
authors.forename: Nikos A
authors.initials: NA
authors.lastname: Kametas
mesh_terms: D000328:Adult; D001132:Arm / Q000033:anatomy & histology*; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000295:instrumentation*; D003971:Diastole; D005260:Female; D006801:Humans; D008875:Middle Aged; D009991:Oscillometry; D011225:Pre-Eclampsia / Q000175:diagnosis* / Q000503:physiopathology; D011247:Pregnancy; D011446:Prospective Studies; D013599:Systole; D055815:Young Adult
keywords: Arm circumference; Blood pressure; Oscillometry; Preeclampsia; Validation; Withings BP-800