In this multicentre , randomised , double-masked , placebo-controlled trial , we enrolled corticosteroid unresponsive adult patients ( aged 18 years ) with primary immune thrombocytopenia and a platelet count of less than 3010 ( 9 ) platelets per L. Patients were randomly assigned ( 1:1 ) to four weekly infusions of 375 mg/m ( 2 ) rituximab or placebo .