Performance of Factor <scp>VIII</scp> Extended Half‐Life Product Measurements in External Quality Assessment Programmes

The FVIII results submitted by participants showed that currently available OSA and CA do not provide consistent results in some products with both an under- and over-estimation of the expected recovery based on potency at either concentration level. Results for Afstyla Lonoctocog alfa suggest that centres were not clear on whether OSA results were before or after application of the correction factor (multiplication of initial result by 2).