International Research Collaboration Supported by the U.S. National Institutes of Health: An Analysis of Coauthor Country Affiliations – 2014–23

Importance: International collaboration is a critical component of biomedical and behavioral health research, but recent trends in its extent and impact in research funded by the U.S. National Institutes of Health (NIH), the world’s largest funder of health research, are not well characterized.

Objective: To characterize the extent and scientific impact of international collaboration in NIH‑funded research from 2014 to 2023.

Design, setting, and participants: Bibliometric analysis of NIH‑funded publications from 2014 to 2023 using the InCites Analytics database (Clarivate, London, UK).

Main outcomes and measures: Publication counts and author country affiliations for NIH‑funded publications from 2014 to 2023 and scientific impact measured by Category Normalized Citation Impact (CNCI) for publications in 2023.

Results: The average annual number of NIH‑funded publications from 2014 to 2023 was 112,633; this declined by 25.1% from 2021 to 2023. In 2023, 68.1% of publications had U.S.‑affiliated authors only, 27.4% had both U.S.‑ and non–U.S.‑affiliated authors, and 4.5% had non–U.S.‑affiliated authors only. Overall, 31.9% of NIH‑funded publications had non–U.S.‑affiliated coauthors in 2023, a decline from a peak of 34.1% in 2018. Although CNCI values are not directly comparable across groups, publications with both U.S.‑ and non‑U.S.‑affiliated authors had a higher scientific impact (CNCI = 1.48) than those with U.S. authors only (1.32) or non‑U.S. authors only (1.44).

Conclusions and relevance: International collaboration is a substantial component of NIH‑supported research and is associated with higher citation impact. Nearly one‑third of NIH‑funded publications included non–U.S.‑affiliated coauthors, and these publications demonstrated higher citation impact than those with U.S.‑affiliated authors only, supporting the importance of global collaboration in biomedical research.