Evaluating the Effectiveness of a Published Severity Scoring Index (SSI) to Predict Death in a Cohort of Consecutive Patients with Thrombotic Thromocytopenic Purpura-Hemolytic Uremic Syndrome (TTP-HUS)

APHA Scientific Session and Event Listing

Reginald T. Hooks, TBD, 801 NE 13th St., CHB-333, Oklahoma City, OK 48381, 405-271-8001, Reginald-Hooks@ouhsc.edu

Objective: Evaluate the ability of a published SSI to predict death in TTP-HUS patients and determine if additional features strengthen predictive power. Introduction: Prior to availability of plasma exchange treatment, 90% of adults with TTP-HUS died. Although exchanges decreased mortality to 20%, they require personnel and large commitments of transfusion resources. The Oklahoma TTP-HUS Registry has complete data for all clinically suspected TTP-HUS patients in central, western, and southeastern Oklahoma (1989–2006). A previous study (N=38) developed a SSI to predict death based on four presenting parameters: neurological symptoms, renal impairment, platelet count, and hemoglobin value. Our study utilized the SSI to evaluate the ability to predict death for patients in our registry. Methods: Patients (N=246) were assigned classifications (0=no abnormalities, 1=mild/moderate impairment, 2=severe impairment) for the four parameters based on the SSI criteria, yielding a potential severity score of 0–8/patient. Other variables collected include age, gender, race, and potential disease etiology. Results: For each one-point increase in the SSI, the odds ratio (OR) for predicting death within 30 days is 1.57 (95%CI: 1.19-2.07). Adjusting for age, the OR is 1.42 (95%CI: 1.0601.90). Patients dying within 30 days (n=52) had a mean SSI and age of 6.27 and 59.25 respectively. Survivors (n=194) had a mean SSI and age of 5.64 and 44.26. Conclusions: Analyses indicate the SSI predicts death within 30 days in TTP-HUS patients. The SSI may allow a more rational approach to management, with more intensive treatment for severe patients, and better allocation of transfusion resources.