Randomization and masking
BLIND
Randomization was based on computer-generated permuted blocks of randomized lengths of 4 or 6, stratified by study center. A third-party statistician (Biostatistical Consulting Inc., Lexington, MA, USA), independent of all other study activities, generated the randomization sequence. Information about treatment assignment was concealed from participants, investigators, and research staff; no emergencies occurred that required breaking the blind. TOMAC systems were preprogrammed to active or sham mode prior to shipment to sites by a manufacturer that was not involved with any aspect of study conduct. All procedures and instructions were identical for active and sham treatment. Active and sham devices were physically identical and provided identical visual feedback during operation. A previously validated transient sham design was implemented [