Venous sample is superior to repeated skin-prick testing in blood donor haemoglobin second-line screening

Blood donor haemoglobin concentration (Hb) is commonly measured from a skin-prick sample. However, the skin-prick sample is prone to preanalytical error and variation, which may lead to false deferrals due to low Hb.

We assessed the efficacy of two second-line screening models for the evaluation of blood donors failing the initial skin-prick test. In the venous model (n = 305), Hb was measured from a venous sample at the donation site. In the skin-prick model (n = 331), two additional skin-prick samples were measured. All on-site Hb measurements were performed with HemoCue Hb201+ (HemoCue AB) point-of-care (POC) device. Hb in the venous samples was later also determined with a hematology analyzer (Sysmex XN, Sysmex Co.) to obtain the donor's correct Hb. A questionnaire evaluated Blood Service nurses' preferences regarding Hb assessment.

Significantly less donors were deferred from donation with venous model (40%) than with skin-prick model (51%; chi-square test P = 0·004). Only two donors (0·7%) were incorrectly accepted in the venous model. Further, Blood Service nurses preferred venous model over skin-prick model. After the study, the venous model was implemented nationwide, and in the first two months after implementation, the deferral rate due to low Hb decreased from 2·7% to 1·9%.

A venous sample for blood donor Hb second-line screening significantly decreased low Hb deferrals compared to repeated skin-prick testing without compromising donor safety. Valuable donations can be recovered by implementing a practical second-line screening model based on venous sampling.