 During the screening period and for up to 6 weeks after randomization, a daily prednisone or equivalent regimen of up to 20 mg daily may be initiated to treat the moderate to severe disease activity present at screening. The initial steroid regimen is not required if investigators or patients believe that the risks would outweigh the potential benefits. Patients who do not take any glucocorticoids during the study will be included in the treatment groups and analysis. 