Evaluating Patterns in ADAMTS13 Testing and Time to Plasma Exchange Initiation for Suspected Thrombotic Thrombocytopenic Purpura at a County Hospital

Introduction: Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a life-threatening disease with a mortality 10-20% despite emergent therapeutic plasma exchange (TPE). The distinguishing aspect of iTTP from other thrombotic microangiopathies is a severe deficiency of ADAMTS13 (<10% activity) with laboratory evaluation of ADAMTS13 activity often requiring hours to days; thus, it is not useful for determining whether plasma exchange for TTP should be initiated. Guidelines also recommend TPE initiation within 4-8 hours (Scully 2012). There is limited literature regarding utilization of ADAMTS13 testing in the hospital, and we sought to understand ordering patterns in various clinical contexts, which services ordered ADAMTS13 activity, and if TPE initiation was timely.