Data Sources : We searched PubMed Clinical Queries, the Cochrane Database of Systematic Reviews, Essential Evidence Plus, the . Preventive Services Task Force, and the Institute for Clinical Systems Improvement. In addition, the most recent review articles from the following journals were reviewed: the New England Journal of Medicine , the Journal of the American Medical Association , and American Family Physician . We identified highly cited studies found within these review articles and major databases to include in our review as appropriate. We limited our search timeline to the previous five years. Search dates: October 2011 and October 2013.