Epidemiology

TTP is a rare disorder with an average annual prevalence of around 10 cases per million people and an annual incidence of approximately one new case per million.[13][14][15] In one study, the age-gender standardized incidence of TTP and hemolytic uremic syndrome was reported to be 6.5 cases per million per year in the US.[16] Another study has estimated the incidence of TTP to be 4 to 11 cases per million per year in the US.[17] 

The incidence of TTP and hemolytic uremic syndrome is higher in women and in black people.[17][16] In the US, between 65% and 75% of patients with TTP are women, and up to 44% are black.

Most patients with TTP subsequent to severe von Willebrand factor cleaving enzyme (ADAMTS-13) deficiency are between the ages of 20 and 59 years.[17] Another source reports an average age of 39 years (range, 19 to 71 years).[18]

TTP secondary to HIV infection has been reported in sub-Saharan Africa, most commonly in females (78%) and in those non-compliant with antiretroviral therapy (12.5%).[19]

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