NIH Funding, Research Productivity, and Scientific Impact: a 20-Year Study

Background The Research Project Grant (R01) is the oldest grant mechanism used by the National Institutes of Health (NIH). Receiving an R01 award is often taken as a sign of scientific success. We presented normative data on multiple productivity and impact metrics for a more objective assessment of funded grants' scientific success. Methods All initial R01 grants awarded by NIH in the year 2000 were prospectively followed and evaluated using the numbers of publications and citations, as well as the h-indices at the grant level. We examined the variability, time trends, and relations among these metrics to better understand the funded projects' cumulative output and impact. Results In the 20 years since initial funding, 4451 R01 grants generated a total of 55,053 publications. These publications were cumulatively cited 3,705,553 times over 736,811 citation years. The median number of publications was 8 (25(th), 75(th) percentiles 4, 17) per grant for the entire 20-year duration. The median number of citations and the median h-index were 441 (25(th), 75(th) percentiles 156, 1061) and 7 (25(th), 75(th) percentiles 4, 13) per grant, respectively. The time courses of publication, citation, and accumulation of h-index were highly variable among the awarded grants. Although the metrics were correlated within an award, they reflected the grant's success in different domains. Conclusion Numbers of publications, citations, and h-indices vary greatly among funded R01 grants. When used together, these metrics provide a more complete picture of the productivity and long-term impact of a funded grant.