title: Accuracy of monitors used for blood pressure checks in English retail pharmacies: a cross-sectional observational study.
abstract: BACKGROUND
  Free blood pressure (BP) checks offered by community pharmacies provide a potentially useful opportunity to diagnose and/or manage hypertension, but the accuracy of the sphygmomanometers in use is currently unknown.
  
  
  OBJECTIVE
  To assess the accuracy of validated automatic BP monitors used for BP checks in a UK retail pharmacy chain.
  
  
  METHODS
  Cross-sectional, observational study in 52 pharmacies from one chain in a range of locations (inner city, suburban, and rural) in central England.
  
  
  METHODS
  Monitor accuracy was compared with a calibrated reference device (Omron PA-350), at 50 mmHg intervals across the range 0-300 mmHg (static pressure test), with a difference from the reference monitor of +/- 3 mmHg at any interval considered a failure. The results were analysed by usage rates and length of time in service.
  
  
  RESULTS
  Of 61 BP monitors tested, eight (13%) monitors failed (that is, were >3 mmHg from reference), all of which underestimated BP. Monitor failure rate from the reference monitor of +/- 3 mmHg at any testing interval varied by length of time in use (2/38, 5% <18 months; 4/14, 29% >18 months, P = 0.038) and to some extent, but non-significantly, by usage rates (4/22, 18% in monitors used more than once daily; 2/33, 6% in those used less frequently, P = 0.204).
  
  
  CONCLUSIONS
  BP monitors within a pharmacy setting fail at similar rates to those in general practice. Annual calibration checks for blood pressure monitors are needed, even for new monitors, as these data indicate declining performance from 18 months onwards.
authors.affiliation: Institute of Applied Health Research;
authors.forename: James
authors.initials: J
authors.lastname: Hodgkinson
authors.affiliation: Nuffield Department of Primary Care Health Sciences, NIHR School for Primary Care Research, University of Oxford, Oxford.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Koshiaris
authors.affiliation: Institute of Clinical Sciences, University of Birmingham, Birmingham.
authors.forename: Una
authors.initials: U
authors.lastname: Martin
authors.affiliation: Primary Care Unit, NIHR School for Primary Care Research, Department of Public Health and Primary Care, University of Cambridge, Cambridge.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mant
authors.affiliation: Nuffield Department of Primary Care Health Sciences, NIHR School for Primary Care Research, University of Oxford, Oxford.
authors.forename: Carl
authors.initials: C
authors.lastname: Heneghan
authors.affiliation: Nuffield Department of Primary Care Health Sciences, NIHR School for Primary Care Research, University of Oxford, Oxford.
authors.forename: Fd Richard
authors.initials: FR
authors.lastname: Hobbs
authors.affiliation: Nuffield Department of Primary Care Health Sciences, NIHR School for Primary Care Research, University of Oxford, Oxford.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: McManus
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000295:instrumentation*; D002138:Calibration; D003430:Cross-Sectional Studies; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000517:prevention & control; D008297:Male; D010594:Pharmacies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019722:Sphygmomanometers / Q000592:standards* / Q000706:statistics & numerical data
keywords: blood pressure monitors; calibration; community pharmacy services; hypertension; primary health care