Magnesium sulphate in patients with thrombotic thrombocytopenic purpura (MAGMAT): a randomised, double-blind, superiority trial.

Abstract

Studies have suggested benefits from magnesium sulphate in thrombotic thrombocytopenic purpura (TTP). We aimed to measure the effects of magnesium sulphate supplementation on TTP recovery. In this multicenter, randomised, double-blind, controlled, superiority study, we enrolled adults with a clinical diagnosis of TTP. Patients were randomly allocated to receive magnesium sulphate (6g intravenously followed by a continuous infusion of 6g/24h for 3days) or placebo, in addition to the standard treatment. The primary outcome was the median time to platelet normalisation (defined as a platelet count ≥ 150 G/L). Efficacy and safety were assessed by intention-to-treat. Overall, we enrolled 74 participants, including one who withdrew his/her consent. Seventy-three patients were further analyzed, 35 (48%) allocated to magnesium sulphate and 38 (52%) to placebo. The median time to platelet normalisation was 4days (95% confidence interval [CI], 3-4) in the magnesium sulphate group and 4days (95% CI 3-5) in the placebo group. The cause-specific hazard ratio of response was 0.93 (95% CI 0.58-1.48, p = 0.75). The number of patients with ≥ 1 serious adverse reactions was similar in the two groups. By day 90, four patients in the magnesium sulphate group and two patients in the placebo group had died (p = 0.42). The most frequent adverse event was low blood pressure occurring in 34% in the magnesium sulphate group and 29% in the placebo group (p = 0.80). Among patients with TTP, the addition of magnesium sulphate to the standard of care did not result in a significant improvement in time to platelet normalisation.