title: Interarm blood pressure difference in people with diabetes: measurement and vascular and mortality implications: a cohort study.
abstract: OBJECTIVE
  Differences in blood pressure between arms are associated with vascular disease and increased mortality; this has not been reported in diabetes. We explored these associations, and assessed reference standard and pragmatic measurement techniques, in people with diabetes and in nondiabetic controls.
  
  
  METHODS
  A prospective cohort study in Devon, England, recruited 727 people with type 1 or type 2 diabetes and 285 nondiabetic controls. Simultaneous repeated measurements of bilateral blood pressure were made at recruitment. Data were used to inform a pragmatic measurement strategy. Interarm differences were examined for cross-sectional associations with target organ disease and prospective mortality associations (median follow-up 52 months).
  
  
  RESULTS
  We found 8.6% of participants with diabetes and 2.9% of controls had systolic interarm differences ≥10 mmHg. Single pairs of blood pressure measurements had high negative predictive values (97-99%) for excluding interarm differences. Systolic interarm differences ≥10 mmHg in diabetes were associated with peripheral arterial disease (odds ratio [OR] 3.4 [95% CI 1.2-9.3]). Differences ≥15 mmHg were associated with diabetic retinopathy (OR 5.7 [1.5-21.6]) and chronic kidney disease (OR 7.0 [1.7-29.8]). Systolic interarm differences were associated prospectively with increased cardiovascular mortality: hazard ratios 3.5 (1.0-13.0) for ≥10 mmHg and 9.0 (2.0-41.0) for ≥15 mmHg.
  
  
  CONCLUSIONS
  Blood pressure should be measured in both arms during initial assessment in diabetes. Systolic interarm differences can be excluded with a single pair of measurements. In the population with diabetes, systolic differences may be associated with an increased risk of morbidity and mortality.
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, University of Exeter Medical School, Exeter, Devon, U.K. c.e.clark@exeter.ac.uk.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Clark
authors.affiliation: NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital and University of Exeter Medical School, Exeter, Devon, U.K.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Steele
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, University of Exeter Medical School, Exeter, Devon, U.K.
authors.forename: Rod S
authors.initials: RS
authors.lastname: Taylor
authors.affiliation: NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital and University of Exeter Medical School, Exeter, Devon, U.K.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: Peninsula Collaboration for Leadership in Applied Health Research and Care (PenCLAHRC), University of Exeter Medical School, Exeter, Devon, U.K.
authors.forename: Obioha C
authors.initials: OC
authors.lastname: Ukoumunne
authors.affiliation: Primary Care Research Group, Institute of Health Services Research, University of Exeter Medical School, Exeter, Devon, U.K.
authors.forename: John L
authors.initials: JL
authors.lastname: Campbell
mesh_terms: D000368:Aged; D001132:Arm / Q000098:blood supply*; D001794:Blood Pressure; D001795:Blood Pressure Determination; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000401:mortality*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D015996:Survival Rate; D013599:Systole