SERUM LACTATE-DEHYDROGENASE AND PLATELET COUNT PREDICT SURVIVAL IN THROMBOTIC THROMBOCYTOPENIC PURPURA

A significant number (some 20%) of patients with thrombotic thrombocyt openic purpura do not respond to standard therapy and die. We reasoned that early identification of those who are likely to fail standard th erapy would allow the rational introduction of other treatment modalit ies. To this end we prospectively evaluated 27 consecutive patients, e xamining serum LDH levels and platelet counts as markers of disease ac tivity and as predictors of outcome. All patients were treated, accord ing to a written protocol, with high volume plasma exchange (35 ml/kg) , prednisone, aspirin, and persantine. Twenty-one of the 27 patients ( 78%) are alive following therapy. Initial LDH and platelet values did not distinguish between the survivors and nonsurvivors. However, by da y 3 of therapy both LDH levels and platelet counts differed significan tly between the two groups. Mean day 3 LDH level for survivors was 364 units/L, and for nonsurvivors, 891 units/L (P < 0.005). Mean day 3 pl atelet count for survivors was 119,000/mu L, and for nonsurvivors, 46, 000/mu L (P < 0.005). Receiver Operator Characteristic curves were con structed and assessed by calculating the area under the curve. This an alysis showed that LDH is able to discriminate survivorship one day ea rlier than platelet count. Both LDH level and platelet count are excel lent predictors of survival, under standard therapy, after 3 days of t reatment. Early identification of those at greatest risk will facilita te the early institution and evaluation of alternative methods of trea tment, such as splenectomy, intravenous Ig, or Vincristine. (C) 1994 W iley-Liss, Inc.