Worldwide, U.S., and U.S. NIH-funded cardiovascular research articles, 1996–2006, by article study characteristics and methodology.

Articles may belong to more than one category, thus the sum of the categories do not necessarily equal the total. Unspecified, general research are research articles with no specified subtype. Miscellaneous articles are journal articles without scientific content, such as bibliographies, biographies, comments, letters, historical articles, guidelines, editorials, news, indices, legal cases, interviews, and consensus statements. Additional information on publication characteristics and methodologies is available at the National Library of Medicine website, at http://www.nlm.nih.gov/mesh/pubtypes2008.html.