K99-R00 Evaluation: A Striking Gender Disparity

Jul 21 2014 Published by under Uncategorized

In a recent post, I examined the NIH K99-R00 (Pathway to Independence) program. Looking at two cohorts of individuals who received K99 awards in FY2007 and FY2008, this analysis revealed that 91% of these 360 awardees transitioned from the K99 phase to the R00 phase, indicating that they had found suitable academic positions. Further, of those with such positions, 51% had obtained R01 funding through the present and some others had received other types of grants.

Over the process of organizing these data, I noticed that the fraction of women receiving K99 awards appeared to be lower than that for men. In order to examine this point more systematically, I assigned gender to these 360 awardees based on name and web searches. Overall, 142 of the 360 (or 39%) of the K99 awardees in these two cohorts are women. This is consistent with the value reported by NIH for this program.

Of the 218 men with K99 awards, 201 (or 92%) went on to activate the R00 portion. Of the 142 women, 127 (or 89%) went on to these R00 phase. These differences in these percentages are not statistically different.

Of the 201 men with R00 awards, 114 (57%) have gone on to receive at least 1 R01 award to date. In contrast, of the 127 women with R00 awards, only 53 (42%) have received an R01 award. This difference is jarring and is statistically significant (P value=0.009).

These results are summarized graphically below:

Men-Women-K99-R00-R01 percent

To investigate this further, I looked at the two cohorts separately. For the FY2007 cohort, 70 of the 108 men (65%) with R00 awards have received R01 grants whereas only 31 of the 62 women (50%) have (P value = 0.07). For the FY2008 cohort, 44 of the 93 men (47%) with R00 awards have received R01s whereas only 22 of the 65 women (34%) have (P value = 0.10). The lack of statistical significance is due to the smaller sample sizes for the cohorts separately rather than any difference in the trends for the separate cohorts, which are quite similar.

What could account for these disparities? Of course, it is unknown at this point if the differences reflect differences in R01 success rate as this would depend on the number of applications submitted by each applicant. I do not have access to data regarding the numbers of applications submitted by these grantees (although NIH does and could do this analysis).

One possibility is that the disparities is due to differences in the timing of funding for men versus women, that is, women might become R01 funded at more similar rates, but a greater disparity is observed at this point because of the lack of time for follow-up after the K99 award. To examine this point, I looked at the percentage of first R01 grants awarded each year to men and women as shown below:


The curves for men and women for each cohort are quite similar. This does not support the hypothesis that the timing of R01 funding is primarily responsible for the observed gender disparity.

Another factor that I considered is the impact of other R01-like awards, primarily the NIH Director's New Innovator (DP2) awards, on the analysis. Overall, nine K99-R00 awardees have received DP2 awards. Of these, six are men and three are women. Interestingly, three of these six men have subsequently received additional R01 awards whereas none of the three women have. In addition, one male K99 awardee received a Pioneer (DP1) award. The inclusion of these additional grants does not significantly affect the overall conclusion about the occurrence of a gender disparity.

Confirmation of and further analysis of these disparities is certainly warranted. Indeed, the K99-R00 program may be highly appropriate for such analyses as investigators at similar career stages competed for initial support and then obtained relatively comparable resources to launch their independent careers.

22 responses so far

  • DrugMonkey says:

    Blockbuster finding, even if it is what the NIH history would predict.

  • DrugMonkey says:

    With small-numbers programs like this, you would think NIHdom would have the same attentional capture you did. It should stick out.

    Yet another example of why the first step is awareness.

    • datahound says:

      Agreed. I was surprised when I did this analysis and am now trying to think through the possible sources of the disparity, how to sort them out, and how to address them going forward.

      • drugmonkey says:

        Seniority is out.

        Scores are (*probably) out.

        Topic domain / funding IC?


        *anybody heard anything about NIH ICs balancing the sex of PIs on K99/R00s? I myself have been struck by what seems to be a suspiciously good sex ratio, compared with R01. but that may be some sort of confirmation bias at work.

  • arlenna says:

    Wow, this IS striking. I would love to see the data on success rates on this. I hope NIH will look at it (or can they anonymize and share it? Do they do that?).

    • datahound says:

      I am encouraging my contacts at NIH to do this analysis. I hope they will follow up in a timely manner on this.

  • Ola says:

    Probably says a lot about the type of mentoring available to M/F junior faculty, in the R01 writing process (which is somewhat more nuanced than the earlier submissions these folks will have been raised on). If all the "mentors" for junior faculty in a department are old dudes, is it any wonder that this pipeline runs dru at the exact time mentor ship is needed most?

    • datahound says:

      It is important to know how much of the disparity is due to differences in the rate of R01 application versus the success rate per application. NIH will need to provide these data and I hope that they will do the analysis (it would be easy with access to the data).

  • […] has some very interesting analyses up regarding NIH-wide sex differences in the success of the K99/R00 […]

  • DJMH says:

    Wow, interesting analysis. Really hope NIH follows up.

  • Davis Sharp says:

    I wonder if the publication records are similar between the male and female R01 applicants. Also, is there an institute bias, i.e. are the me being funded by ICs with higher paylines?

    • datahound says:

      There are certainly differences between the institutes and centers regarding how they handle these awards. I am working on a new post with these data. The publication record issue is more challenging to tackle, but I am trying to see what I can do.

  • eeke says:

    Thank you for this analysis. Instead of (or in addition to) focusing on trends of specific IC's (as suggested by DM), can you evaluate study section behavior? Maybe this is too sensitive - do female applicants routinely score worse (or better) in specific study sections?

    • datahound says:

      For these cohorts, the number of awards is too small to look at study section behavior and such information is only publicly available for funded grants (as opposed to other applications). NIH could do this analysis but, as you say, it could be sensitive and challenging to interpret.

  • Sue B says:

    Can a similar analysis be done for a similar cohort of postdocs funded by an F-award? Are you more likely to get an R01 within 5 years of being funded by a K99/R00 compared to having an F-award for your postdoctoral training? I would also be curious about the gender bias for this cohort too.

    • datahound says:

      This analysis is more challenging since most F32 awardees do not go on to academic positions and their is no marker (corresponding to the R00 award) in NIH RePORTER that indicates obtaining an academic position. I am confident that, overall, the probability of getting an R01 after a F32 is lower than that for a K99-R00, but cannot predict the outcome if the F32 recipients are limited to those who do obtain academic positions.

    • LIZR says:

      There are a couple of recent blog posts at Grantome that examine funding rates for F32 and K99 recipients:


      I assume that most K99 awardees are a few years further into their postdocs than the average F32 awardees. If you compare 2005 F32 awardees to 2007 K99 awardees, you can see a huge difference in the fraction of awardees with R01's (F32: 14%, vs K99: 59%). However, like datahound said, it is hard to compare F32 to K99 awardees. We don't even know what fraction of F32 awardees attempted to find an independent academic position or what fraction became PIs.

      • datahound says:

        Thanks for the links. These are pleasingly consistent with my results and expectations. The F32 comparison, while intuitively tempting, is quite challenging, both in execution and interpretation.

      • Sue B says:

        Thanks for sharing this information.

  • drugmonkey says:

    From Sally Rockey:

    A specific issue that recently has recently created interesting conversations in the blogosphere is whether female K99/R00 awardees were less likely to receive a subsequent R01 award compared to male K99/R00 awardees. We at NIH have also found this particular outcome among K99/R00 PIs and have noted that those differences again stem from differential rates of application. Of the 2007 cohort of K99 PIs, 86 percent of the men had applied for R01s by 2013, but only 69 percent of the women had applied. - See more at: http://nexus.od.nih.gov/all/2014/08/08/women-in-biomedical-research/#sthash.a5rSVau1.dpuf

  • […] my post noting the occurrence of differences between men and women K99 awardees in their likelihood of […]

  • […] recent analyses and discussions of gender differences in the K99/R00 transition to R01 rate are reflection […]

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