Blood draws up to 3% of blood volume in clinical trials are safe in children

Abstract

Aim: Recommendations for maximum blood draw in children range from 1 to 5% despite limited evidence. The aim of the study was to assess the safety of blood draws in children aged six months to 12 years targeting volumes of 3% of total blood volume.

Methods: Children who experienced three-monthly blood draws during participation in one of three investigators initiated clinical trials conducted in our institution were examined. In total, 629 venous blood draws were performed in 141 children. Adverse events and blood counts were assessed.

Results: Overall, 608 adverse events were reported. None of these included symptoms that reflected concerns on blood draw volumes or frequency. Anaemia and red cell or haemoglobin measurements outside the normal age range were not observed. A reduction in haemoglobin, haematocrit, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and mean corpuscular volume was noted in children participating in one of the three trials analysed.

Conclusion: Regular blood draws of up to 3% of total blood volume were not associated with signs of anaemia or hypovolaemia in young children. We suggest that the European recommendations be revised for clinical studies in which children are not exposed to treatments that are associated with anaemia risk.

Keywords: Blood collection; Blood draw safety in children; Paediatric research; Safe phlebotomy; Single blood draw.

Figure 1

Dot plots of haemoglobin, red blood counts (RBC) and haematocrit at baseline and at end of treatment or after 12 months of treatment (as appropriate) in the Pre‐POINT, Pre‐POINT‐Early and Fr1da‐Insulin‐Intervention studies, respectively. Red horizontal lines indicate the groupwise medians. P‐values were derived from Wilcoxon signed‐rank tests, with and without adjustment for the estimated natural change in each parameter by increasing age between baseline and later visits. Plotting and calculations were done in all children who had both a baseline and an end of treatment/12‐month visit.