Importance: The US National Institutes of Health (NIH) is the largest funder of biomedical and behavioral research in the world. International collaborative research-a subset of NIH's portfolio-is critical to furthering the agency's health research mission.
Objective: To quantify the extent of the NIH's international collaborations and the relative importance of this research through the lens of publications.
Design, setting, and participants: This cross-sectional study used bibliometric data from the Web of Science database to analyze trends in the growth of NIH-funded publications from January 1, 2009, to December 31, 2017, and examined their importance using national affiliations of all coauthors listed, h indices, and citation impact scores. All countries with coauthor affiliations in NIH-funded publications during the study period were included. Data were analyzed from October 22 through November 16, 2018.
Exposures: Country affiliations of coauthors' institutions in NIH-funded publications indexed in the Web of Science database from 2009 to 2017.
Main outcomes and measures: Trends in the number of NIH-supported publications with non-US coauthors during a 9-year period and their relative importance assessed by h index per country and category-normalized citation impact (CNCI) for groups of country affiliations in 2017.
Results: From 2009 to 2017, the annual count of NIH-funded publications increased 46.2% from 67 041 to 98 002. This increase was driven in part by an increase in publications with a non-US author alone or as a collaborator with a US author compared with those exclusively with US authors, reflected by an increase in the percentage of publications with non-US coauthors from 28.3% to 34.8%. Moreover, in 2017, publications coauthored by US-affiliated and non-US-affiliated investigators had a higher mean CNCI (1.99) than those whose authors were only US affiliated (1.54) or non-US affiliated (1.35). China became the most frequent publishing partner, with 6982 coauthored publications and the greatest increase over time among non-US countries.
Conclusions and relevance: In a 9-year period when the NIH budget remained relatively unchanged, an increase in the number of publications occurred with a growing trend toward more international collaborations of authorship; these publications also had a higher CNCI than publications with only US or only non-US authors. The findings suggest that international collaboration is a vital and growing component of the NIH's research output and likely reflects increased globalization of biomedical research.