1. Department of Medicine, University of Virginia Health System, Charlottesville (R.M.C).
2. Department of Medicine, Case-Western Reserve University School of Medicine, Cleveland, OH (J.T.W.).
3. Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN (S.J.T.).
4. Departments of Epidemiology and Medicine, Tulane University, New Orleans, LA (P.K.W.).