Personalized prophylaxis.

Prophylaxis is the recommended treatment for people with severe haemophilia. It is unlikely that a single prophylactic regimen, for example based on weight, would be optimal for all patients and therefore each individual should have a personalized regimen, agreed between themselves and their haemophilia centre. This regimen should take into account the individual's bleeding pattern, the condition of their musculoskeletal system, level and timing of physical activity and measurement of coagulation factor in their blood. It is important to recognize that prophylactic regimens are likely to need to change with time as the circumstances of an individual change. For example, activity may change with age or with the season and an individual's factor VIII pharmacokinetics vary with age. Knowledge of a patient's pharmacokinetics is likely to help personalize prophylaxis when combined with other information. Factor VIII pharmacokinetics are simple to measure in routine clinical practice and can be adequately calculated from 2 to 3 blood samples combined with a simple to use computer program. Prophylaxis is expensive and, in countries with a limited health care budget, ways to improve its cost effectiveness need to be considered to allow increased access to this treatment. For example, increasing the frequency of prophylaxis can dramatically reduce the amount of treatment required to sustain measureable factor levels and hence reduce cost. The introduction of longer-acting coagulation factors may necessitate a change in concepts about prophylaxis because whilst these agents may sustain an apparently adequate trough level with fewer infusions, the length of time a person spends at a low level will be increased and this could increase the risk of bleeding, especially at the time of increased physical activity. There is convincing evidence that prophylaxis is the optimal therapy for severe haemophilia, optimizing treatment for each individual and increasing access to this treatment modality are important goals for the future.