This article presents health spending projections from 2006 to 2016 including: health spending as a share of the gross domestic product (GDP) and prescription drug spending.  The authors acknowledge the impact of Medicare Part D on drug payers; however, they anticipate little change in overall drug spending over the covered period.  

Poisal, J. A., Truffer, C., Smith, S., Sisko, A., Cowan, C., Keehan, S. et al. (2007). Health spending projections through 2016: modest changes obscure part D's impact. Health Affairs, 26(2), w242-53. 21 Feb. 2007. DOI: 10.1377/hlthaff.26.2.w242. http://content.healthaffairs.org/cgi/content/abstract/26/2/w242 © 2007 by Project HOPE.