Heterogeneity of terminology and clinical definitions in adult idiopathic thrombocytopenic purpura: a critical appraisal from a systematic review of the literature

Clinical definitions and terminology vary greatly in clinical studies on idiopathic thrombocytopenic purpura (ITP). An objective assessment of this heterogeneity may be of interest, providing a basis for standardizing ITP terminology. A systematic review of the recent literature on ITP in adults was carried out. The following items were extracted from the articles for comparison: platelet count cut-off values to decide treatment and type of response; timing for evaluating the response to treatment; evaluation of bleeding symptoms; criteria to define initial, chronic and refractory forms. A total of 79 papers, among those published or referenced from 2000 to 2006, were considered eligible. No consensus among the different authors was found on several issues, including:platelet count for definition of ITP; grading of severity; definition of chronic ITP; platelet threshold to start treatment; platelet count to define response to treatment and timing for evaluating the response to therapy. There was only major consensus for the length of disease duration required to diagnose chronic ITP, the criteria for splenectomy and the definition of refractory ITP. Confusing terminology and an unacceptable heterogeneity of clinical definitions used for management decisions and to describe outcomes were evident in recent ITP literature. This makes it very difficult to compare different studies and to share data and clinical experiences. A standardization of terminology and definitions used in ITP is urgently needed.