Overweight individuals are at increased risk for thrombotic thrombocytopenic purpura.

Our understanding of the pathophysiology of thrombotic thrombocytopenic purpura, TTP, has increased dramatically in the past few years with the identification of the role of ADAMTS13. Nonetheless, risk factors for the development of acute TTP are few. Informally, obesity was felt to be common in patients with TTP and so a formal study was undertaken to further define this association. We report our data in 105 patients with classical TTP as defined by thrombocytopenia and microangiopathic hemolytic anemia. We found that marked obesity is a previously unrecognized risk factor with an associated odds ratio of 7.6. Interestingly, despite this increased risk, obesity might well be associated with lower mortality, although this did not reach statistical significance.