We analyzed the association of the following baseline variables with improvement : myositis clinical subgroup , demographics , myositis damage , clinical and laboratory parameters , core set measures , rituximab treatment , and myositis autoantibodies ( antisynthetase , anti-Mi-2 , anti-signal recognition particle , anti-transcription intermediary factor 1 [ TIF-1 ] , anti-MJ , other autoantibodies , and no autoantibodies ) .