[1] Stanford Sch Med, Evaluat Sci Unit, Stanford, CA 94305 USA
[2] VA Palo Alto Hlth Care Syst, Palo Alto, CA USA
[3] Case Western Reserve Univ, Cleveland, OH 44106 USA
[4] Stanford Univ, Sch Med, Stanford, CA 94305 USA
[5] VA Greater Los Angeles Healthcare Syst, Los Angeles, CA USA
[6] Univ Calif Los Angeles, Los Angeles, CA USA
[7] Wilmington VA Med Ctr, Wilmington, DE USA