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.
McDonald R, Mead N, Cheraghi-Sohi S, Bower P, Whalley D. Governing the ethical consumer: identity, choice and the primary care medical encounter. Sociol Health Illn. 2007 Apr 1;29(3):430-56.