title: A study of inter-arm blood pressure differences in primary care.
abstract: OBJECTIVE
  To investigate whether there are inter-arm blood pressure differences that are of clinical importance to general practice.
  
  
  METHODS
  Pragmatic study with randomised order of use of left or right arm carried out in routine surgeries in an inner city and suburban general practice.
  
  
  METHODS
  There were 237 patients presenting opportunistically for blood pressure measurement to a nurse or general practitioner.
  
  
  METHODS
  95% limits of agreement between measurements on the left and right arm and bias between arms.
  
  
  RESULTS
  Large inter-arm blood pressure differences exist reflected in wide 95% limits of agreement; -16 mm Hg to 24 mm Hg for the right minus the left arm diastolic blood pressure. There is a small but statistically significant bias to the right arm blood pressure measuring higher than the left (3.7 mm Hg diastolic, 2.4 to 5 mm Hg 95% confidence intervals). An interarm difference of 10 mm Hg or greater for diastolic blood pressure occurred in 40% of subjects and a difference of 20 mm Hg or more for systolic blood pressure occurred in 23% of subjects.
  
  
  CONCLUSIONS
  In a primary care setting blood pressure should be measured routinely in both arms. If one arm is to be preferred for pragmatic clinical purposes, then this should be the right arm.
authors.affiliation: Teams Family Practice, Teams, Gateshead, Tyne and Wear NE8 2PJ, UK. Paul.Cass@cableinet.co.uk
authors.forename: P
authors.initials: P
authors.lastname: Cassidy
authors.forename: K
authors.initials: K
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001132:Arm / Q000098:blood supply*; D001794:Blood Pressure / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008875:Middle Aged; D015588:Observer Variation; D011320:Primary Health Care; D011446:Prospective Studies; D006113:United Kingdom / Q000453:epidemiology