The ability of clinical and laboratory findings to predict in-hospital death in patients with thrombotic thrombocytopenic purpura in an internal and emergency medicine department

Abstract

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening syndrome characterized by microangiopathic anemia, thrombocytopenia, diffuse microvascular thrombosis, and ischemia. It is associated with very low levels of ADAMTS-13. Measurement of ADAMTS-13 levels is used for diagnostic and prognostic purposes, but in every-day clinical practice, this type of analysis is not always readily available. In this retrospective study, we evaluated prognostic value of clinical and laboratory findings in patients with TTP. Materials and methods: We retrospectively investigated patients with clinically diagnosed TTP treated in a unit of Internal and Emergency Medicine (1996-2007). Clinical and laboratory findings were collected and analyzed in order to assess their ability to predict in-hospital death. Results: Twelve patients were identified (mean age 59 + 22 years; 58% were women). Five (42%) died during the hospitalization, and the variables significantly associated with this outcome were: a delay between diagnosis and symptom onset (HR 1.36; 95% CI 1.04-1.78; p < 0.05); a higher severity score (HR 1.48; 95%CI 1,23-3.86; p < 0.05); hemodynamic instability with hypotension and/or shock (HR 3.35; 95%CI 3.02-9.26; p < 0.01); a higher schistocyte count on blood smear (HR 1.84; 95%CI 1.04-3.27; p < 0.05); and higher lactate values (HR 1.85; 95%CI 1.08- 3.16; p < 0.05). Conclusions: TTP is a rare and potentially fatal disease with protean manifestations. Delayed diagnosis after symptom onset is a major determinant of poor outcome. Hypotension and shock are also prognostically unfavourable. Laboratory evidence of cardiocirculatory compromise (i.e., elevated lactate levels) and extension of the disease process (i.e., schistocyte count > 3) are predictive of in-hospital death, independently of the hemodynamic profile on admission.