title: Inter-arm blood pressure difference and mortality: a cohort study in an asymptomatic primary care population at elevated cardiovascular risk.
abstract: BACKGROUND
  Differences in blood pressure between arms are associated with increased cardiovascular mortality in cohorts with established vascular disease or substantially elevated cardiovascular risk.
  
  
  OBJECTIVE
  To explore the association of inter-arm difference (IAD) with mortality in a community-dwelling cohort that is free of cardiovascular disease.
  
  
  METHODS
  Cohort analysis of a randomised controlled trial in central Scotland, from April 1998 to October 2008.
  
  
  METHODS
  Volunteers from Lanarkshire, Glasgow, and Edinburgh, free of pre-existing vascular disease and with an ankle-brachial index ≤0.95, had systolic blood pressure measured in both arms at recruitment. Inter-arm blood pressure differences were calculated and examined for cross-sectional associations and differences in prospective survival. Outcome measures were cardiovascular events and all-cause mortality during mean follow-up of 8.2 years.
  
  
  RESULTS
  Based on a single pair of measurements, 60% of 3350 participants had a systolic IAD ≥5 mmHg and 38% ≥10 mmHg. An IAD ≥5 mmHg was associated with increased cardiovascular mortality (adjusted hazard ratio [HR] 1.91, 95% confidence interval [CI] = 1.19 to 3.07) and all-cause mortality (adjusted HR 1.44, 95% CI = 1.15 to 1.79). Within the subgroup of 764 participants who had hypertension, IADs of ≥5 mmHg or ≥10 mmHg were associated with both cardiovascular mortality (adjusted HR 2.63, 95% CI = 0.97 to 7.02, and adjusted HR 2.96, 95% CI = 1.27 to 6.88, respectively) and all-cause mortality (adjusted HR 1.67, 95% CI = 1.05 to 2.66, and adjusted HR 1.63, 95% CI = 1.06 to 2.50, respectively). IADs ≥15 mmHg were not associated with survival differences in this population.
  
  
  CONCLUSIONS
  Systolic IADs in blood pressure are associated with increased risk of cardiovascular events, including mortality, in a large cohort of people free of pre-existing vascular disease.
authors.affiliation: Primary Care Research Group, University of Exeter Medical School, Exeter, Devon.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Clark
authors.affiliation: Primary Care Research Group, University of Exeter Medical School, Exeter, Devon.
authors.forename: Rod S
authors.initials: RS
authors.lastname: Taylor
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh.
authors.forename: Isabella
authors.initials: I
authors.lastname: Butcher
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh.
authors.forename: Marlene Cw
authors.initials: MC
authors.lastname: Stewart
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh.
authors.forename: Jackie
authors.initials: J
authors.lastname: Price
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh.
authors.forename: F Gerald R
authors.initials: FG
authors.lastname: Fowkes
authors.affiliation: NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, and Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: Primary Care Research Group, University of Exeter Medical School, Exeter, Devon.
authors.forename: John L
authors.initials: JL
authors.lastname: Campbell
mesh_terms: D001132:Arm / Q000098:blood supply*; D001241:Aspirin / Q000627:therapeutic use; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D011159:Population Surveillance; D011320:Primary Health Care; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin
keywords: blood pressure; cardiovascular diseases; cohort studies; inter-arm difference; primary care; subclavian artery stenosis