Caveats for the use of operational electronic health record data in comparative effectiveness research - Hersh, WR; Weiner, MG; Embi, PJ; Logan, JR; Payne, PR; Bernstam, EV; Lehmann, HP; Hripcsak, G; Hartzog, TH; Cimino, JJ; Saltz, JH (Med Care, 2013)