NIH’s dedicated K23 trial pathway was associated with more K-trial leadership but no detectable gain in new trials

Research funders often train investigators by funding a project, expecting the experience to produce leaders of the next one. Delivering the funded project and leading new work are different outcomes. In 2018 the US National Institutes of Health (NIH) created a dedicated clinical trial pathway for its K23 mentored career development awards. Using registry records for 1,847 K23 awardees and a language-model measurement corrected against blinded human review, we compared awardees whose awarded plans proposed their own trial with those whose plans did not, before and after the change. The pathway was followed by more leadership of the award-supported trial (difference in differences, 13.7 percentage points; 95% confidence interval, 5.7 to 21.2) but no detectable gain in leadership of distinct new trials ( − 3.8; − 14.4 to 6.9), including over seven years. The K-trial estimate exceeded the new-trial estimate by 17.4 points (5.3 to 29.7) under every measurement correction. The additional supported trials were registered with the awardee as principal investigator and started at rates similar to earlier ones, whereas whether more awardees led any trial depended on the correction. Because groups were defined by awarded plans, the design cannot fully separate changes in behaviour from changes in who was funded. A training pathway can raise delivery of the work it funds without a detectable increase in leadership of further trials. As NIH consolidates its career awards and ends K support for trial conduct, evaluations should measure both outcomes.