A case-controlled multicenter study of vasovagal reactions in blood donors: influence of sex, age, donation status, weight, blood pressure, and pulse.

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.

STUDY DESIGN AND 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.