Impact Of Patient, Disease and Plasma Exchange Characteristics On The Outcomes Of Thrombotic Thrombocytopenic Purpura In a Retrospective Cohort Study
Authors: Khattak Amna G , Haq Mansoor Ul , Kaweeta Fnu , Kocak Mehmet , Bradley Robert , Weir Alva B. 
Published: October 2019

Abstract

Introduction
Thrombotic thrombocytopenic purpura (TTP) is a serious medical condition characterized by endothelial injury and the formation of small vessel platelet-rich thrombi. If untreated, TTP-HUS in adults typically follows a progressive course in which irreversible renal failure, progressive neurologic deterioration, cardiac ischemia, and death are common outcomes. The mainstay of treatment for most patients with TTP is plasma exchange. Compared to the mortality rate of 90 percent prior to the use of plasma exchange, the mortality rate for patients treated with plasma exchange is 25 percent or less. Retrospective evidence shows no difference in outcomes based upon difference in composition of plasma exchange fluids.
Based upon our observation, we hypothesized that patients treated with replacement fluid containing less than 100 percent fresh frozen plasma will have inferior outcomes in terms of achieving remission with frequent exacerbation, relapse and TTP related death.

Method
We conducted a retrospective chart review of 98 patients diagnosed and treated for first episode of TTP with plasma exchange at a tertiary referral center between 2004 and 2011. We recorded various patient and disease characteristics including gender, race, BMI, blood group, ADAMTS levels and any identifiable etiologies for secondary TTP. Based upon the composition of plasma replacement fluid, we divided to cohort into three groups; 100 percent fresh frozen plasma (FFP), Plasma with 50 % albumin and lastly a group which received both types of replacement fluids. We looked at the relationship of study outcomes; rate of remission, exacerbation, relapse and TTP related death with various patient and disease characteristics. We also compared the outcomes; rate of remission, exacerbation, relapse and TTP related death between the three types of plasma exchange groups in our cohort.

Result
The vast majority of our cohort comprised on African Americans (N= 84) females (N=64). Median age of the cohort was ---. Forty four patients were defined as having Idiopathic TTP where as secondary causes associated with TTP where identified in 53 patients. Forty eight patients received 100 % FFP, 23 received FFP in combination with 50 % albumin and 27 received both type of replacement fluids during plasma exchange. There was no statistically significant difference in the rate of remission, exacerbation, relapse and TTP related death based on gender, race, obesity, etiology and type of blood group. Patients with lower ADAMTS 13 level had higher likelihood of relapse (30.2% versus 8.3% p = 0.017). Patient achieved remission at a median duration of 40, 38 and 40 days in the 100 % plasma, 50/50 albumin and the combination groups respectively. There was no statistically significant difference in the rate of remission, exacerbation, relapse and TTP related death in the three treatment groups.

Conclusion
Amongst various patient and disease characteristics, only a low ADAMTS 13 level was significantly associated with increased rate of relapse. The median duration to remission was similar in the three plasma exchange groups irrespective of the type of replacement fluid. The type of replacement fluid used during plasma exchange has no impact on the rate of remission, exacerbation, relapse and TTP related death. However, a randomized prospective study is warranted to definitely answer this question.

Disclosures:
No relevant conflicts of interest to declare.