[1] VA Boston Healthcare Syst, VA Cooperat Studies Program, 151MAV,150 S Huntington Ave, Jamaica Plain, MA 02130 USA
[2] Univ Vermont, Complex Syst Ctr, Burlington, VT 05405 USA
[3] Harvard Med Sch, Boston, MA 02115 USA
[4] Dana Farber Canc Inst, Boston, MA 02215 USA
[5] Univ Chicago, Ctr Data Intens Sci, Chicago, IL 60615 USA
[6] Boston Univ, Sch Med, Boston, MA 02118 USA