[1] Philadelphia VA Med Ctr, VISN Ctr Evaluat PACT 4, Philadelphia, PA USA
[2] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[3] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[4] Univ Penn, Robert Wood Johnson Clin Scholar Program, Philadelphia, PA 19104 USA