Human immunodeficiency virus-associated thrombotic microangiopathies: clinical characteristics and outcome according to ADAMTS13 activity.

Human immunodeficiency virus (HIV) infection is a risk factor for thrombotic microangiopathy (TMA). We sought whether a severe deficiency in ADAMTS13, the enzyme specifically involved in the cleavage of von Willebrand factor, was associated with specific presenting features and outcome in HIV-associated TMA. In this prospective, multicentre, case-control study, 29 patients of 236 in the French Network on TMA had an HIV-associated TMA. Seventeen patients with severe ADAMTS13 deficiency (ADAMTS13 <5% HIV(+) group) were compared to 12 patients with a detectable ADAMTS13 activity (ADAMTS13 >or=5% HIV(+) group). HIV(+) patients were also compared to 62 patients with idiopathic TMA, either with (45 patients, ADAMTS13 <5% idiopathic group) or without (17 patients, ADAMTS13 >or=5% idiopathic group) severe ADAMTS13 deficiency. ADAMTS13 <5% HIV(+) patients had less AIDS-related complications than ADAMTS13 >or=5% HIV(+) patients (23.5% versus 91.6%, respectively, P = 0.0005) and their median CD4(+) T cell count was higher (P = 0.05). TMA-associated death rate was higher in ADAMTS13 >or=5% HIV(+) patients than in ADAMTS13 <5% HIV(+) patients (50% versus 11.7%, respectively, P = 0.04). In ADAMTS13 <5% patients, TMA-associated death rate was comparable between HIV(+) and idiopathic patients (15.5% in idiopathic patients, P-value was non-significant). By contrast, TMA-associated death rate in ADAMTS13 >or=5% HIV(+) patients was higher than in idiopathic patients (11.7% in idiopathic patients, P = 0.04). In conclusion, HIV-associated TMA with severe ADAMTS13 deficiency have less AIDS-related complications and a higher CD4(+) T cell count. TMA prognosis is better and comparable to this of idiopathic forms.

Prognostic value of inhibitory anti-ADAMTS13 antibodies in adult-acquired thrombotic thrombocytopenic purpura.

In order to assess the prognostic value of inhibitory anti-ADAMTS13 antibodies in thrombotic thrombocytopenic purpura (TTP), we performed a multicentre prospective study of 33 adult patients with idiopathic acquired TTP. Patients were treated with high-dose plasma infusion and therapeutic plasma exchange. Patients without (group 1, n = 12) and with (group 2, n = 21) detectable inhibitory anti-ADAMTS13 antibodies were compared for clinical presentation, treatment and outcome. Both groups were comparable for clinical presentation. All patients in group 1 achieved a sustained complete remission within a median of 7 d [95% confidence interval (CI), 4-18], which required a median plasma volume of 235 ml/kg (range, 131-1251). In group 2, 17 patients achieved a durable complete remission within a median of 23 d (95% CI, 11-32) (P = 0.001). Median plasma volume was 718 ml/kg (range, 219-3107) (P = 0.02). In group 2, there was a trend for more episodes of flare-up than in group 1 (13 vs. 3, respectively, P = 0.07). Four patients, all from group 2, died (P = not significant). The relapse rate was comparable between both groups. We suggest that TTP with detectable inhibitory anti-ADAMTS13 antibodies displays a worse prognosis, relative to a delayed platelet count recovery, a higher plasma volume requirement to achieve complete remission, and a trend for more frequent episodes of flare-up.