Boswell, MD, K., Kwong, PharmD, PhD, W. J., & Kavanagh, MSc, S. (2018). Burden of opioid-associated gastrointestinal side effects from clinical and economic perspectives: A systematic literature review. Journal of Opioid Management, 6(4), 269–289. https://doi.org/10.5055/jom.2010.0025