Applicability of 2009 international consensus terminology and criteria for immune thrombocytopenia to a clinical pediatric population

Abstract

Background: Since pediatric immune thrombocytopenia (ITP) is relatively infrequent, comparisons among clinical studies are critical but have previously been limited by differences in terminology. In 2009, an international working group (IWG) developed consensus criteria to enhance comparability in future studies in adults and children. Methods: We performed a retrospective medical record review of all pediatric ITP patients seen at a single children's hospital with a first visit between 2003 and 2010 and applied both historical (criteria Hist) and IWG (criteria IWG) ITP criteria to available clinical data. Results: Among the 505 patients seen for ITP over 7 years, 98% could be classified as "acute" or "chronic" ITP using the criteria Hist, while only 90.7% could be classified as "newly diagnosed," "persistent," or "chronic" ITP using the criteria IWG (P<0.01). Only 33.7% met criteria IWG for severe ITP, whereas 77.4% met criteria Hist for severe ITP. A striking difference was that overall response to therapies was lower if the criteria IWG were used rather than the criteria Hist, particularly for IVIG (55.4% vs. 70%, P=0.02) and rituximab (35.3% vs. 83.3% P=0.05). Only 2 subjects (0.4%) met the criteria IWG for refractory ITP. Conclusions: Most ITP patients could easily be classified using the 2009 criteria IWG. Limitations to applying the criteria IWG included absence of treatment response durations, incomplete definition of pediatric "refractory ITP," and exclusion of secondary ITP. Nevertheless, the criteria IWG were more clinically relevant given the reliance on definitions based on bleeding and their ability to be applied prospectively. The utility of using the criteria IWG within prospective trials remains to be determined. © 2011 Wiley Periodicals, Inc.