Outcome measures and treatment endpoints other than platelet count in childhood idiopathic thrombocytopenic purpura

Abstract

Therapy for children with acute idiopathic thrombocytopenic purpura (ITP) has been controversial, in great part because it is not evidence based. Some physicians are activists, treaters, or interventionists with regard to therapy of ITP whereas others have been described as nontreaters or noninterventionists. Platelet count (which is often extremely low in ITP) has generally been employed as a surrogate measure of hemorrhagic risk even though life-threatening or fatal bleeding is rare. Virtually all of the randomized clinical trials conducted in childhood ITP have focused on platelet counts as the sole outcome measure. However, other determinants should influence clinical decision making, including assessment of bleeding tendency. Laboratory testing has not been helpful in this regard, but clinical assessment by means of semiquantitative bleeding scores may prove more useful than simply designating a patient as having a "dry" or "wet" purpura. The side effects as well as costs (direct and indirect) of therapy must also be considered when attempting to weigh the merits of drug therapy against their risks. Finally, the effect of ITP and its treatment on health-related quality of life should be determined. Measurement tools to assess each of these alternative outcome measures are in early stages of development. Employing them in addition to platelet counts in future clinical trials will allow treatment to be based more on scientific data than treatment philosophy.