In this phase @ , multicentre , placebo-controlled trial , @ adults with active PsA were randomised ( stratified by site , weight ( @ kg / > @ kg ) , methotrexate use ) to ustekinumab @ mg or @ mg at week @ , week @ , q@ weeks or placebo at week @ , week @ , week @ and crossover to ustekinumab @ mg at week @ , week @ and week @ .