Severity of acute TTP episodes and survival of patients with hTTP during prospective follow-up. (A) Kaplan-Meier curve for overall survival of 87 patients with hTTP during prospective follow-up, during which 4 male patients died. Causes of death were: large cerebral infarction in a 33-year-old, heart failure at age 38 years, lethal arrhythmia with asystole during sepsis at age 56 years, and death of unknown cause at age 79 years. According to the treating physicians, none of the patients at the time of death was considered to have an acute TTP episode. Still, 3 of the 4 deaths were categorized as fatal outcome of cerebrovascular or cardiovascular events (acute hTTP episode, severity score 4). (B) The severity of acute TTP episodes are graded as follows (Table 1): score 1, mild; score 2, moderate, usually temporary clinical symptoms; score 3, severe, clinical symptoms producing often permanent morbidity; and score 4, fatal outcome of typical TTP episode and/or death of cerebrovascular or cardiovascular event, or a female patient’s death during pregnancy.