title: A case-controlled multicenter study of vasovagal reactions in blood donors: influence of sex, age, donation status, weight, blood pressure, and pulse.
abstract: BACKGROUND
  Vasovagal reactions occur in a small, but significant number of blood donors. These reactions may decrease return donation and disrupt blood collection activities. The purpose of this study was to define the contributory role of sex, age, weight, blood pressure, and pulse in vasovagal reactions with syncope in blood donors.
  
  
  METHODS
  A retrospective case-control study involved 1890 blood donors with syncope from three large United States blood centers during 1994 and 1995. Case controls and random population controls were used in a logistic regression analysis to determine the significance of individual variables to syncopal reactions.
  
  
  RESULTS
  Female donors, young donors, first-time donors, low-weight donors, and donors with low predonation blood pressure had higher absolute donation reaction rates than other donors. When each variable was adjusted for other variables by regression analysis, age, weight, and donation status (first-time or repeat donor) were significant (p<0.0001), and sex, predonation blood pressure, and predonation pulse were not. The most important variables, in descending order, were age, weight, and donation status (first-time or repeat donor).
  
  
  CONCLUSIONS
  Donation-related vasovagal syncopal reactions are a multifactorial process determined largely by age, weight, and first-time donor status.
authors: American Red Cross Blood Services, Connecticut Region, Farmington 06032, USA.
authors: J J
authors: JJ
authors: Trouern-Trend
authors: R G
authors: RG
authors: Cable
authors: S J
authors: SJ
authors: Badon
authors: B H
authors: BH
authors: Newman
authors: M A
authors: MA
authors: Popovsky
mesh_terms: D000328:Adult; D001782:Blood Donors; D001794:Blood Pressure; D001835:Body Weight; D016022:Case-Control Studies; D004244:Dizziness / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006185:Habituation, Psychophysiologic; D006339:Heart Rate; D006801:Humans; D007022:Hypotension / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D010167:Pallor / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D018962:Phlebotomy / Q000009:adverse effects*; D012189:Retrospective Studies; D019462:Syncope, Vasovagal / Q000453:epidemiology* / Q000209:etiology; D014481:United States / Q000453:epidemiology