Randomization and Blinding
Following the protocol, each hospital was allocated to administer patients consecutive periods of a standard dose of enoxaparin or aspirin, with the initial treatment order being randomized. Hospitals were randomized in permuted blocks of 4 by statisticians from the South Australian Health and Medical Research Institute (SAHMRI), independent of study investigators. The randomization sequence was generated using an online application and provided to an unblinded data manager from SAHMRI. Each hospital was allocated to a treatment sequence by SAHMRI staff the week prior to enrolling patients. Hospitals were advised to crossover once the sample size for the first treatment group was met, which was monitored by AOANJRR staff.Participating hospitals and patients were not masked to treatment allocation. Study investigators and the data safety monitoring board (DSMB) were masked to treatment assignment during the trial and all analyses.