Pain research from 1975 to 2007: a categorical and bibliometric meta-trend analysis of every Research Paper published in the journal, Pain.

In an attempt to characterize the nature of pain research, every one of the 4525 Research Papers published in the journal, Pain, from its inception until the end of 2007, was examined by a single individual using a consistent set of criteria, and was coded for its essential features in four domains: the purpose of the study (e.g., characterization of a pain syndrome, evaluation of the role of a molecule), the subjects of the study (patients, human "normals", animals), the pain states characterized or induced (clinical pain and experimental stimuli), and the dependent measures examined (e.g., behaviors, questionnaires, neural firing). For papers involving pain patients, the clinical conditions under study were coded as well. These categorical data were combined with bibliometric data obtained from citation databases. Together, the data allow an examination of 32-year trends in pain research, and comprise a data compendium fully searchable or sortable by any interested individual.