Clinical presentation and treatment outcomes in a South African thrombotic thrombocytopenic purpura cohort with and without HIV

Background: HIV is the most common cause of secondary thrombotic thrombocytopenic purpura (TTP) in South Africa. Objectives: To assess the clinical presentations and outcomes of patients treated for HIV-associated and idiopathic TTP. Method: We conducted a retrospective cohort study of patients consecutively diagnosed with TTP from 2010 to 2020 at Groote Schuur Hospital. Patients were identified by reviewing hospital and Western Cape Blood Services records. Kaplan-Meier curves and log-rank tests were used to evaluate remission rates, both overall and by HIV status and treatment group. Logistic regression models were used to identify predictors of remission and relapse. Results: One hundred and thirty-nine patients were included, 85.6% of whom were HIV positive. There were no significant differences in the TTP pentad features by HIV status. Most patients achieved remission (71.9%) with a median time of eight days. Remission occurred significantly earlier in those treated with fresh frozen plasma only, suggesting less severe disease (median = 8 days [interquartile range 6-10]), compared to those requiring plasma exchange, suggesting more severe disease (median = 12 days [interquartile range 8-22]). The overall mortality in the 10-year period was 38.9%, with 10.8% of the surviving patients relapsing after 6 months. There were no significant differences in remission status, time to remission, mortality or relapse by HIV status. All HIV-positive patients who relapsed had defaulted their antiretroviral therapy (ART). Conclusion: HIV status did not affect patient outcomes in our cohort. ART is important in preventing HIV-associated TTP and relapse.