Donor return after temporary deferral

The consequences of temporary predonation deferral are unsatisfactorily understood. Studies have found that deferral negatively impacts future donor return. However, the applicability of these findings across centers has not been established.

Using a cohort design, presenting donors with a temporary deferral in 2006 to 2008 in one of six categories (low hematocrit [Hct], blood pressure or pulse, feeling unwell, malaria travel, tattoos or piercing and related exposures, or could not wait or second thoughts) were passively followed for up to a 3-year period for the time to first return after deferral expiration at six US blood centers. Time-to-event methods were used to assess return. We also analyzed which donor characteristics were associated with return using multivariable logistic regression.

Of 3.9 million donor presentations, 505,623 resulted in deferral in the six categories. Low Hct was the most common deferral, had the shortest median time to return (time in days when 50% of deferred donors had returned), and had the largest cumulative proportion of donors returning. Deferrals of shorter duration had better return. Longer-term deferrals (up to 1 year in length) had the lowest cumulative return proportion, which did not exceed 50%. Return was associated with previously identified factors such as repeat donor status, older age, and higher educational attainment regardless of the type of deferral. In addition, return was associated with having been born in the United States and donation at fixed sites.

The category of temporary deferral influences the likelihood of future return, but the demographic and donation factors associated with return are largely consistent regardless of the deferral.