title: Type and accuracy of sphygmomanometers in primary care: a cross-sectional observational study.
abstract: BACKGROUND
  Previous studies identified worrying levels of sphygmomanometer inaccuracy and have not been repeated in the era of digital measurement of blood pressure.
  
  
  OBJECTIVE
  To establish the type and accuracy of sphygmomanometers in current use.
  
  
  METHODS
  Cross-sectional, observational study in 38 Oxfordshire primary care practices.
  
  
  METHODS
  Sphygmomanometers were evaluated between 50 and 250 mmHg, using Omron PA350 or Scandmed 950831-2 pressure meters.
  
  
  RESULTS
  Six hundred and four sphygmomanometers were identified: 323 digital (53%), 192 aneroid (32%), 79 mercury (13%), and 10 hybrid (2%) devices. Of these, 584 (97%) could be fully tested. Overall, 503/584 (86%) were within 3 mmHg of the reference, 77/584 (13%) had one or more error of 4-9 mmHg, and 4/584 (<1%) had one or more error of more than 10 mmHg. Mercury (71/75, 95%) and digital (272/308, 88%) devices were more likely to be within 3 mmHg of the reference standard than aneroid models (150/191, 78%) (Fisher's exact test P = 0.001). Donated aneroid devices from the pharmaceutical industry performed significantly worse: 10/23 (43%) within 3 mmHg of standard compared to 140/168 (83%) aneroid models from recognised manufacturers (Fisher's exact test P<0.001). No significant difference was found in performance between manufacturers within each device type, for either aneroid (Fisher's exact test P = 0.96) or digital (Fisher's exact test P = 0.7) devices.
  
  
  CONCLUSIONS
  Digital sphygmomanometers have largely replaced mercury models in primary care and have equivalent accuracy. Aneroid devices have higher failure rates than other device types; this appears to be largely accounted for by models from indiscernible manufacturers. Given the availability of inexpensive and accurate digital models, GPs could consider replacing aneroid devices with digital equivalents, especially for home visiting.
authors.affiliation: Department of Primary Health Care, University of Oxford, Oxford. christine.acourt@phc.ox.ac.uk
authors.forename: Christine
authors.initials: C
authors.lastname: A'Court
authors.forename: Richard
authors.initials: R
authors.lastname: Stevens
authors.forename: Sarah
authors.initials: S
authors.lastname: Sanders
authors.forename: Alison
authors.initials: A
authors.lastname: Ward
authors.forename: Richard
authors.initials: R
authors.lastname: McManus
authors.forename: Carl
authors.initials: C
authors.lastname: Heneghan
mesh_terms: D001795:Blood Pressure Determination / Q000295:instrumentation / Q000592:standards; D003430:Cross-Sectional Studies; D004739:England; D004867:Equipment Design; D058006:General Practice / Q000295:instrumentation* / Q000592:standards; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D011785:Quality Assurance, Health Care; D012680:Sensitivity and Specificity; D019722:Sphygmomanometers / Q000592:standards*