The effect of plasma donation frequency on total serum protein, immunoglobulin G and donor safety: A non-inferiority...

The safety of varying plasma donation frequencies remains unclear. This non-inferiority randomized controlled trial investigated the effect of plasma donation frequency on total serum protein (TSP), immunoglobulin G (IgG) concentrations, additional biomarkers, adverse events (AEs) and psychological distress.

In this trial, 120 male donors were randomized into three groups: high-frequency plasma donors (HFPDs, three times every 2 weeks), regular-frequency plasma donors (RFPDs, once every 2 weeks) and a control group (whole blood donation every 3 months). Blood samples were collected biweekly from baseline until the last donation in Week 16 and 4 weeks after the last donation.

HFPDs completed median (range) 21.5 (1-24), RFPDs 8 (1-8) and controls 2 (1-2) donations. HFPDs had lower concentrations of TSP and IgG compared to controls, with a mean difference (95% confidence interval [CI]) of -5.5 g/L (-7.4, -3.6) and -2.8 g/L (-3.8, -1.8), respectively. Within-group analysis revealed significant reductions, which increased with the frequency of donations, in TSP, IgG, IgG subclasses, immunoglobulin M (IgM), immunoglobulin A (IgA), ferritin and haemoglobin. Many of the biomarkers required more than 4 weeks to return to baseline levels. Only mild AEs were reported, and plasma donation frequency had no effect on psychological distress.

High- and regular-frequency plasmapheresis substantially reduces concentrations of TSP, IgG and other biomarkers, with greater reductions at higher donation frequencies. Further research is needed to assess the long-term health implications of frequent plasma donation.