3006 — Risk Factors Associated with Idiopathic Thrombotic Thrombocytopenic Purpura: Surveillance, Epidemiology, and Risk Factors for TTP (SERF-TTP) Study

Pandey DK (University of Illinois Chicago), Zakarija A (Northwestern University), Bandarenko N (Duke University), Luu TH (Northwestern University), Cursio J (University of Illiniois Chicago), Richey EA (Northwestern University), Winters J (Mayo Clinic), Sarode R (University of Texas Southwestern), Kiss J (The Institute of Transfusion Medicine, Pittsburgh, PA), Bennett CL (VA Center for Management of Complex Chronic Conditions, Jesse Brown VAMC, Northwestern University)

Objectives:
Thrombotic thrombocytopenia purpura (TTP) is a severe, multisystem, thrombotic microangiopathy associated with a 90% mortality rate when untreated. Limited information on risk factors for TTP is available due to rarity of the condition and lack of epidemiologic studies. The SERF-TTP study is the first large prospective multicenter matched case-control study designed to investigate the risk factors for TTP using population-based controls.

Methods:
Cases of idiopathic TTP were identified at 10 participating apheresis centers upon referral for therapeutic plasma exchange (TPE). Excluded were patients with organ or allogeneic stem cell transplant, anti-neoplastic therapy or malignancy. Information on current symptoms, medical history, medications used in the three months prior to diagnosis, family history, health behavior, and demographics were obtained by questionnaire. Medical records were abstracted for laboratory and clinical data. At least two controls were identified for each case matched for age (± 5 years), gender, and geographic area. They were recruited by random digit dialing using CATI system and were administered the same questionnaire. Multivariable conditional logistic regression analysis was performed to estimate odds ratio (OR) and 95% confidence interval (CI).

Results:
Among 86 cases, 70% were between ages 18-49 years old, 81% were women, 43% were black, and 95% were non-Hispanic. Factors associated with increased TTP risk included use of anti-platelet agents (aspirin, clopidogrel, and dipyridamole) (OR 19.8, 95% CI 3.3-116.8), non-steroidal anti-inflammatory agents (OR 3.2, 95% CI 1.5-6.9), and connective tissue disease diagnosis (OR 10.5, 95% CI 2.2-51.2).

Implications:
The results indicate a significant association between certain medications or medical conditions and the risk of TTP. An ongoing TTP registry is warranted to characterize TTP syndromes associated with various risk factors and investigate underlying pathophysiology.

Impacts:
Anti-platelet and anti-inflammatory agents are commonly prescribed to veterans in the VA health care system. Awareness of the risks for TTP posed by these agents and incorporation of these agents in VA’s current active adverse drug reaction surveillance efforts will enhance the quality of health care delivered to veterans.