title: Vasovagal reaction rates and body weight: findings in high- and low-risk populations.
abstract: BACKGROUND
  The effect of weight on vasovagal reaction rates has not been evaluated in high- and low-risk populations or in first-time versus repeat blood donors. In addition, vasovagal reaction rates and weight have not been evaluated based on solicited information.
  
  
  METHODS
  A total of 1073 Caucasian high school students from randomly selected whole-blood drives in 2001 and 949 randomly selected Caucasian donors from the general donor population in 2001 and 2002 were subdivided into weight groups and evaluated for vasovagal reaction rates.
  
  
  RESULTS
  The high school population had a much higher vasovagal reaction rate than the general donor population (8.0 vs. 2.6%). The vasovagal reaction rate was inversely proportional to body weight in first-time blood donors in both populations, but the trend was not as well defined in repeat blood donors. Solicitation of information from the general donor population increased the vasovagal reaction detection rate by 2.5 times (from 2.6% to 6.5%), and it is suggested that the vasovagal reaction rate might be as high as 27 percent in first-time general donors who weighed between 110 and 139 pounds.
  
  
  CONCLUSIONS
  Body weight is a very important determinant of vasovagal reaction rates in first-time donors, but previous successful blood donation appears to mitigate the effect of body weight on vasovagal reaction rates. Solicitation of information from blood donors increases the number of vasovagal reactions detected and enhances the data.
authors.affiliation: American Red Cross Blood Services, Southeastern Michigan Region, Detroit, Michigan 48201, USA. newmanb@usa.redcross.org
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Newman
mesh_terms: D000293:Adolescent; D000328:Adult; D001782:Blood Donors; D001835:Body Weight; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008824:Michigan / Q000453:epidemiology; D018962:Phlebotomy / Q000009:adverse effects; D012307:Risk Factors; D019462:Syncope, Vasovagal / Q000453:epidemiology* / Q000209:etiology