Feasibility of blood self-sampling with HemaSpot HF for Anti-Clostridium tetani Toxin IgG detection.

Health research in humans often requires biosamples, e.g. blood. However, collecting venous blood samples poses multiple logistic challenges and needs to be carried by practitioners at study centres. Using self-collected samples of dried blood spots is an attractive alternative, but its feasibility remains to be determined. We investigated the feasibility (including acceptance) of a self-sampling device called HemaSpot HF (HS) employing the use case of anti-Clostridium tetani toxin IgG detection among 154 volunteers. Of those, n = 49 underwent an additional venous blood puncture (VBP) by medical staff (gold standard) as and control for user errors, which were determined by adding serum on HS filter paper (HemaForm (HF)). Antibody concentrations were analysed via ELISA and the serological status was determined using different cut-off values (COV). Most participants (85%) found the self-sampling using the HS device (fully) acceptable. Sensitivity for HS ranged from 70% (95% CI 0.55; 0.83; COV: 1.0 lU/mL) to 100% (95% CI 0.93; 1.00; COV: 0.01 and 0.1 lU/mL), and for HF 85% (95% CI 0.72; 0.94; 1.0 lU/mL) to 100% (95% CI 0.93; 1.00; COV: 0.01 and 0.1 lU/mL). The correlation between HS and VBP was r = 0.73 (95% CI 0.56; 0.83), and between HF and VBP r = 0.81 (95% CI 0.69; 0.89). The average difference in antibody concentration between HS and VBP was 1.1 IU/mL (Bland-Altman plots) and increased with the IgG concentration. Therefore, despite high acceptability, self-sampling with HS needs further improvement to be a reliable alternative to VBP.