To ask the Secretary of State for Health and Social Care, with reference to commissioning criterion 6b of NHS England’s Criteria for the Prescribing of Enhanced Half-Life Blood Factors, published in September 2016, what assessment he has made of the appropriateness of maximum conversion ratios for children; and if he will direct NHS England to introduce a higher maximum conversion ratio for children as a result of their higher factor IX usage per kg of body weight.

NHS England’s criteria for the Prescribing of Enhanced Half-Life Blood Factors were produced by clinical experts. The conversion ratio is applied in the situation of switching a patient from a standard half-life Factor IX (FIX) to an enhanced half-life FIX. As higher doses of FIX may be just as likely in paediatric patients, regardless of whether the FIX is a standard or enhanced half-life product, the conversion ratios accommodate higher doses (on a unit per kilo gram bodyweight basis) if these are clinically indicated for the patient, irrespective of age. On this basis, NHS England does not have any current plans to amend the conversion ratios.