Sixteen of the 77 patients who recovered from their initial episode of TTP (1995-2017) have subsequently died. The probability of patient survival is compared with the expected probability based on the matched age-, race-, and sex-specific mortality rates from the reference US population obtained from the data of the Centers for Disease Control. Broken lines indicate the 95% confidence intervals around the patient survival. The probability of patient survival and 95% confidence intervals as well as the population probability of death for the United States were calculated using Kaplan-Meier methods with pointwise limits.