Outcome and prognosis of severe thrombotic microangiopathies treated by plasma exchange

Plasma exchange (PE) therapy has dramatically improved the outcome of thrombotic microangiopathies (TMA) in adults. However, resistance to PE, which indicates a poor prognosis, is observed in 1/3 of patients and remains not fully understood. We evaluated in this study the survival and the long-term outcome of severe TMA treated by PE and identified the predictive factors of resistance to PE and of mortality.

Records of adults with severe TMA treated by PE were reviewed. Clinical and biological data, therapeutic delay to PE, plasma volume exchange per procedure, and number of PE sessions were collected. Mortality was assessed at one month and at one-year follow-up. All data were analyzed and compared between survived/deceased and between responder/non-responder patients.

Nineteen females and six males were included. Mean age (+/-SD) was 46.8+/-16.3 years, Glasgow coma score 11+/-3, and Sequential Organ Failure Assessment (SOFA) score 5.8+/-2.8. Nineteen patients partially or fully responded to PE. Twenty patients were alive at one month and 19 at one year. The response to PE was the single discriminating parameter between survivors and non-survivors. A longer delay of PE and a neoplastic cause of TMA were significantly higher in the non-responders.

Severe TMA treated by PE had a fair prognosis, with a survival rate at 76% after one year of follow-up. Unresponsiveness to PE was the only predictive factor of mortality; a neoplastic etiology of TMA and a longer therapeutic delay of PE were predictive of resistance to PE.