Incidence and Risk Factors of Thrombocytopenia in Patients Receiving Intermittent Antiretroviral Therapy: A Substudy of the ANRS 106-Window Trial

Background: Incidence and risk factors for thrombocytopenia in patients discontinuing highly active antiretroviral therapy (HAART) have not been fully investigated. Methods: Well-suppressed patients on HAART were randomized to continuous (CT) or intermittent therapy (IT) for 96 weeks. Incidence of thrombocytopenia (< 150 X 10(3) platelets/mm(3)) was assessed and multivariate analysis performed to identify baseline predictors. Correlations were assessed between platelet, CD4, CD8 T-cell counts, and viral load after treatment interruption. Results: Three hundred ninety-one patients were included, with a median baseline platelet count of 243,000/mm(3). The incidence of thrombocytopenia at week 96 was significantly higher in the IT versus the CT arm (25.4% versus 9.8%, respectively, P < 0.001) and median time to thrombocytopenia was 9 weeks. In multivariate analysis, the IT strategy: odds ratio (OR)=4.1 (2.1-7.9; P < 0.0001), a history of thrombocytopenia: OR = 11.9 (2.4-57.9; P = 0.002), and a low baseline platelet count: OR = 3.4 (2.3-5.1; P < 0.0001) were associated with an increased risk of thrombocytopenia. Also, after treatment interruption, changes from baseline in platelet counts were correlated with changes in CD4 T-cell counts and plasma HIV RNA levels (P < 0.001 for both). Conclusions: Intermittent therapy is associated with a high incidence of thrombocytopenia, especially among patients with low platelet counts and a history of thrombocytopenia.