The bleeding risk and natural history of idiopathic thrombocytopenic purpura in patients with persistent low platelet counts

Background: No firm data are available on the natural history of idiopathic thrombocytopenic purpura (ITP) or on mortality rates or frequency of major bleeding episodes associated with this condition. The disease is thought t o have a relatively benign course, despite the frequent occurrence of very low platelet counts. This prevailing conception often guides therapeutic de cisions. Objective: To estimate the bleeding risk of ITP involving persistent low pl atelet counts (<30 x 10(9)/L) and its impact on prognosis. Design: Age-adjusted bleeding risk was derived from a pooled analysis of IT P clinical series based on a systematic literature search. The risk estimat e was incorporated into a Markov model to determine its impact on prognosis . Results: Seventeen case series complied with inclusion criteria, including 1817 patients with ITP. There were 49 cases of fatal hemorrhage over an est imated 1258 to 3023 patient-years at risk. The rate of fatal hemorrhage bef ore age adjustment was estimated at between 0.0162 and 0.0389 cases per pat ient-year. Age-adjusted rates were 0.004, 0.012, and 0.130 cases per patien t-year for age groups younger than 40, 40 to 60, and older than 60 years, r espectively. Predicted 5-year mortality rates ranged from 2.2% for patients younger than 40 years to 47.8% for those older than 60 years. A 30-year-ol d woman remaining thrombocytopenic due to ITP was predicted to lose 20.4 ye ars (14.9 quality-adjusted life years) of her potential life expectancy. At age 70, predicted loss was 9.4 years (5.0 quality-adjusted life years). Conclusions: Idiopathic thrombocytopenic purpura with persistent low platel et counts carries a grave prognosis. Therefore, an active therapeutic appro ach in the clinical management of affected patients should be considered. I n view of the significant potential implications of the model results, we c all for initiating a well-designed prospective inception cohort study of pa tients with ITP.