Disease activity was assessed by myositis disease activity assessment (MYOACT), muscle enzymes and C-reactive protein (CRP) were measured by routine laboratory techniques; autoantibodies by immunoprecipitation or by immunoblot.
In a multivariate analysis pvl remained significantly associated with ESR and CRP levels at presentation and blood culture positive for S aureus. pvl+ status and younger age were associated with myositis on MRI.