Candrilli SD, Davis KL, Iyer S. Impact of constipation on opioid use patterns, health care resource utilization, and costs in cancer patients on opioid therapy. J Pain Palliat Care Pharmacother. 2009 Sep 1;23(3):231-41.
Bray JW, Davis KL, Graver L, Schroeder D, Buck JA, Dilonardo J, Vandivort R. Mental health and substance abuse treatment utilization among individuals served by multiple public agencies in 3 states. J Behav Health Serv Res. 2005 Jan 1;32(3):282-93.