HIV-Associated Thrombotic Thrombocytopenic Purpura

Abstract 4677

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening form of microangiopathic hemolysis that can be associated with HIV infection, and has previously been reported to be associated with low CD4 counts. The existing literature on HIV-TTP is very small and largely made up of small case series generated through databases of patients with HIV. As a result, reports have tended to focus on HIV parameters with limited information available regarding the presentation, management and outcome of the TTP itself. We conducted a retrospective review of TTP cases referred to the pheresis units St. Michael’s Hospital and Vancouver General Hospital in Vancouver between July 1993 and May 2011. Ten cases of HIV associated TTP were identified (8 male; 2 female). Median age at presentation was 38 years. One patient had been previously diagnosed and treated for TTP at a different institution. Average duration of HIV infection prior to TTP diagnosis was 5 years (range 0 to 11). Median CD4 count at TTP diagnosis was 79 × 10⁶/ml (range 2 to 326). Median platelet count at presentation was 14 × 10⁶/ml (range 5 to 233), median haemoglobin was 74 g/L (range 61 to 133), all patients had an LDH > 2x the upper limit of normal, and all for whom data was available (8/10) had fragmentation on blood film. Creatinine was elevated in 9 of 10 patients. ADAMTS13 was assessed in 3 of 10 patients and was deficient in one. Five of 10 patients had fever. At presentation, 6 of 10 patients had neurological symptoms (most commonly seizures and/or confusion), but none suffered permanent neurological deficits. All patients were treated with plasmapheresis and received a median of 16 exchanges (2-56). Four patients received concurrent steroids, two patients received IVIG, and one patient received pheresis, steroids IVIG, vincristine and rituximab. Eight of 10 patients achieved complete remissions, one patient achieved a partial response, and one died on treatment. Four of the responding patients subsequently relapsed (0.6 to 13.8 months after the initial episode of TTP); two achieved second remissions, and two died on treatment. In conclusion, our series of HIV associated-TTP confirms previous reports that HIV-TTP tends to occur in patients with CD4 counts less than 200. Complete remissions can be achieved with standard management. However, based on our small series, relapses may be more common and mortality greater than in the general TTP population.