Delayed Adverse Reactions Following Whole-Blood and Plateletpheresis Donation: A Prospective Observational Study From a Tertiary-Care Blood Center.

BACKGROUND AND AIM: Delayed adverse reactions occurring after donors leave the blood center may be underrecognized by routine on-site hemovigilance. Comparative data on delayed reactions following whole-blood donation and plateletpheresis within the same institutional setting remain limited. This study aimed to determine the frequency and pattern of delayed adverse reactions and evaluate their associations with donor age, sex, donation status, and donation type. METHODS: This prospective observational study included 17,923 donors (17,633 whole-blood and 290 plateletpheresis) at a single tertiary-care blood center from June 2020 to May 2021. Four-week telephone follow-up was completed by 16,292/17,923 (90.9%) donors using a structured interview schedule. Reaction-specific proportions were calculated using the enrolled donation-group denominators. Associations were assessed using Pearson's chi-square or exact tests, as appropriate; odds ratios (ORs) were crude and unadjusted. RESULTS: Whole-blood donors most frequently reported fatigue (587/17,633 {3.33%}), bruising (390/17,633 {2.21%}), painful arm (283/17,633 {1.61%}), and hematoma (102/17,633 {0.58%}). Among plateletpheresis donors, hematoma (11/290 {3.79%}) and bruising (9/290 {3.10%}) were most frequent. Plateletpheresis was associated with higher unadjusted odds of hematoma (OR: 6.77, 95% CI: 3.57-12.84; p<0.001), allergy (OR: 14.12, 95% CI: 4.03-49.47; p=0.002), delayed bleeding (OR: 17.37, 95% CI: 3.59-84.09; p=0.009), and nerve irritation (OR: 13.58, 95% CI: 2.91-63.35; p=0.013). Among whole-blood donors, bruising, fatigue, and painful arm were more frequent among females (all p<0.001). Plateletpheresis subgroup findings were considered exploratory because of small subgroup numbers. CONCLUSIONS: Delayed-reaction profiles differed across donation modalities, with local venous-access complications more prominent after plateletpheresis. These unadjusted single-center findings require cautious interpretation and multicenter validation.