title: Association of a difference in systolic blood pressure between arms with vascular disease and mortality: a systematic review and meta-analysis.
abstract: BACKGROUND
  Differences in systolic blood pressure (SBP) of 10 mm Hg or more or 15 mm Hg or more between arms have been associated with peripheral vascular disease and attributed to subclavian stenosis. We investigated whether an association exists between this difference and central or peripheral vascular disease, and mortality.
  
  
  METHODS
  We searched Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane, and Medline In Process databases for studies published before July, 2011, showing differences in SBP between arms, with data for subclavian stenosis, peripheral vascular disease, cerebrovascular disease, cardiovascular disease, or survival. We used random effects meta-analysis to combine estimates of the association between differences in SBP between arms and each outcome.
  
  
  RESULTS
  We identified 28 eligible studies for review, 20 of which were included in our meta-analyses. In five invasive studies using angiography, mean difference in SBP between arms was 36·9 mm Hg (95% CI 35·4-38·4) for proven subclavian stenosis (>50% occlusion), and a difference of 10 mm Hg or more was strongly associated with subclavian stenosis (risk ratio [RR] 8·8, 95% CI 3·6-21·2). In non-invasive studies, pooled findings showed that a difference of 15 mm Hg or more was associated with peripheral vascular disease (nine cohorts; RR 2·5, 95% CI 1·6-3·8; sensitivity 15%, 9-23; specificity 96%, 94-98); pre-existing cerebrovascular disease (five cohorts; RR 1·6, 1·1-2·4; sensitivity 8%, 2-26; specificity 93%, 86-97); and increased cardiovascular mortality (four cohorts; hazard ratio [HR] 1·7, 95% CI 1·1-2·5) and all-cause mortality (HR 1·6, 1·1-2·3). A difference of 10 mm Hg or higher was associated with peripheral vascular disease (five studies; RR 2·4, 1·5-3·9; sensitivity 32%, 23-41; specificity 91%, 86-94).
  
  
  CONCLUSIONS
  A difference in SBP of 10 mm Hg or more, or of 15 mm Hg or more, between arms might help to identify patients who need further vascular assessment. A difference of 15 mm Hg or more could be a useful indicator of risk of vascular disease and death.
  
  
  BACKGROUND
  Royal College of General Practitioners, South West GP Trust, and Peninsula Collaboration for Leadership in Applied Health Research and Care.
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, Devon, UK. Electronic address: christopher.clark@pms.ac.uk.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Clark
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, Devon, UK.
authors.forename: Rod S
authors.initials: RS
authors.lastname: Taylor
authors.affiliation: Vascular Medicine, Peninsula NIHR Clinical Research Facility and Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, Devon, UK.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: Peninsula Collaboration for Leadership in Applied Health Research and Care, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, Devon, UK.
authors.forename: Obioha C
authors.initials: OC
authors.lastname: Ukoumunne
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, Devon, UK.
authors.forename: John L
authors.initials: JL
authors.lastname: Campbell
mesh_terms: D001132:Arm / Q000098:blood supply*; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000401:mortality* / Q000503:physiopathology*; D006801:Humans; D016491:Peripheral Vascular Diseases / Q000401:mortality* / Q000503:physiopathology*; D012307:Risk Factors; D013349:Subclavian Steal Syndrome / Q000503:physiopathology; D013599:Systole