Evolution of the scientific literature on pain from 1976 to 2007.

Objective: This study traces the evolution of the scientific literature on pain published during the last 30+ years (1976-2007).
Methods: Using the Web of Science, pain-focused journal articles from the Science Citation Index Expanded published in 1977, 1987, 1997, and 2007 were retrieved and analyzed.
Results: The number of pain-related publications rose from 1,562 articles for 1976-77 to 9,159 PubMed for 2006-2007, with slow growth for the period 1976-1995, and rapid increases from 1995-2007. The analysis of contributing countries showed two major players, the United States and the UK; the doubling of the number of countries involved in pain research from 40 in 1977 to 82 in 2007; and the appearance in 2007 of The Netherlands, Turkey, China, and Brazil among the top-15 most prolific contributors. During the 30-year period, the number of journals publishing pain-related research increased nearly 2.5-fold (363 journals in 1977 vs 972 in 2007), including 14 new, international pain-focused journals since 2000. Additionally, while there were only two pain journals (Pain and Headache) in 1977, 15 pain-focused journals were indexed in 2007 with the result that 17 of the top-20 pain-focused journals in 2007 did not exist in 1977.
Conclusion: The rapid evolution and explosion of pain research in the last 30+ years was reflected in substantial changes in the landscape of the contributing countries and in the scientific journals targeted by pain researchers.