By Skills

Introduction

Postdoctoral NIH T32 programs aim to provide select trainees with experience to enable successful career and research development. Here we present data on NIH career development, or K award, and R01 equivalent research grant outcomes of participants in post-doctoral T32 programs.

Cohorts

These analyses are based on the outcomes of 35,528 T32 post-doctoral participants (including 18,671 men and 16,857 women) who matriculated between 1995 and 2009, for whom we had data on age and gender, and who had received MD, MD-PhD, or PhD degrees. We followed them for designation as principal investigator (PI) on subsequent K and R01-equivalent awards (which we’ll refer to as R01 going forward) through 2017. Table 1 shows characteristics and high-level outcomes according to matriculation cohort. Over time, a greater proportion of matriculants were women.

Among all participants, 4,299, or 12%, served as PI on an R01-equivalent award during follow-up. Among the 4,236 who served as PI on a K award, 1,769, or 42%, later supported later served as PI on an R01-equivalent award. Conversely, among the 31,292 who were not PI’s on a K award, only 2,530, or 8%, later served as PI on an R01-equivalent award.

Table 2 shows characteristics according to gender. Men appointed to T32 programs were more likely to have MD or MD-PhD degrees. A greater proportion of men submitted K and R01 applications and received K and R01 awards during follow-up.

Time to First Competing R01 Award

Figure 1 shows Kaplan-Meier event rates for time from T32 matriculation to time to serving as a PI on a first competing R01 award according to cohort. Those in the 2005-2009 cohort (meaning after the end of the NIH doubling) were less likely to eventually be a PI on an award. Figure 2 shows that recipients with MD-PhD degrees were PI’s on awarded grants at greater rates than those with PhD degrees, whereas those with MD degrees were PI’s on awards at the lowest rate. Figure 3 shows that men were supported as PI’s at a greater rate than women. Figures 4 and 5 show that for both men and women, those who matriculated into post-doctoral programs after age 35 had a lower rate of serving as PI on an R01 award.

Table 1: T32 Participant Characteristics According to Matriculation Cohort

Characteristic/Cohort1995-19992000-20042005-2009
Total N (%)11622 (32.7)11768 (33.1)12138 (34.2)
Age (years) at Matriculation30 or less3607 (31.0)3982 (33.8)4298 (35.4)
31 to 355166 (44.5)5181 (44.0)5517 (45.5)
36 or more2849 (24.5)2605 (22.1)2323 (19.1)
DegreeMD3559 (30.6)4161 (35.4)4243 (35.0)
MD-PhD1327 (11.4)1241 (10.5)1130 (9.3)
PhD6736 (58.0)6366 (54.1)6765 (55.7)
GenderMen6440 (55.4)6271 (53.3)5960 (49.1)
Women5182 (44.6)5497 (46.7)6178 (50.9)
Submitted K ApplicationYes1898 (16.3)2423 (20.6)2602 (21.4)
PI on K AwardYes1313 (11.3)1512 (12.8)1411 (11.6)
Submitted R01 ApplicationYes3315 (28.5)2932 (24.9)2047 (16.9)
PI on R01 AwardYes1844 (15.9)1546 (13.1)909 (7.5)

Table 2: T32 Participant Characteristics According to Gender

Characteristic/GenderMenWomen
Total N (%)18671 (52.6)16857 (47.4)
Age (years) at Matriculation30 or less5774 (30.9)6113 (36.3)
31 to 358752 (46.9)7112 (42.2)
36 or more4145 (22.2)3632 (21.5)
DegreeMD6750 (36.2)5213 (30.9)
MD-PhD2530 (13.6)1168 (6.9)
PhD9391 (50.3)10476 (62.1)
Submitted K ApplicationYes3846 (20.6)3077 (18.3)
PI on K AwardYes2386 (12.8)1850 (11.0)
Submitted R01 ApplicationYes4845 (25.9)3449 (20.5)
PI on R01 AwardYes2662 (14.3)1637 (9.7)
Plot showing probability (y axis) and years after matriculation (x axis) for three different matriculation cohorts, probability seems to increase for all as years after matriculation increase

Figure 1: Time to first award according to cohort

Transition Time from First K to First R01 Award

Figure 6 shows corresponding Kaplan-Meier event rates for time from first K award to first competing R01 award according to matriculation cohort. Participants in later cohorts became PI’s on R01 awards more quickly. Figure 7 shows that those with PhD and MD-PhD degrees served as PI’s on R01 awards sooner than those with MD degrees. Figure 8 shows that men were more likely to be a PI on an R01 award sooner.

Multivariable analyses

Table 3 shows a Cox proportional hazards model for time to R01 award. The analyses show adjusted associations of age, gender, degree type, matriculation cohort, and K-award (as a time-dependent covariate) with time to award. Men, recipients with MD-PhD degrees, and recipients of K awards were more likely to become PI’s on R01 awards in less time. The model focuses on those 35,079 participants with at least 7 years of follow-up (since few R01 awards were issued earlier, leading to a violation of the proportional hazards assumption). By bootstrap validation the model performed well with an optimism-corrected concordance statistic of 0.784 (where a value of 1 would imply perfect discrimination and a value of 0.5 would imply that the model performs no better than chance).

Figure 2: Time to first award according to degree

Figure 3: Time to first award according to gender

Figure 4: Time to first award according to age among men

Figure 5: Time to first award according to age among women

Figure 6: Time to first R01 award from first K award according to cohort

Figure 7: Time to first R01 award from first K award according to degree

Figure 8: Time to first R01 award from first K award according to gender

Table 3: Cox Proportional Hazards Model for First Competing R01 Award among T32 Post-doctoral Matriculants for Those with at Least 7 Years of Follow-up

PredictorHR (univariable)HR (multivariable)
Age (years) at Matriculation30 or less
31 to 350.96 (0.89-1.03, p=0.240)0.84 (0.78-0.91, p<0.001)
Degree36 or more0.49 (0.44-0.55, p<0.001)0.46 (0.41-0.52, p<0.001)
MD
MD-PhD2.33 (2.10-2.60, p<0.001)1.78 (1.60-1.99, p<0.001)
Post-Doctoral CohortPhD1.34 (1.23-1.45, p<0.001)2.05 (1.89-2.24, p<0.001)
1995-1999
2000-20041.02 (0.95-1.11, p=0.558)0.97 (0.90-1.05, p=0.458)
Gender2005-2009 Women0.89 (0.81-0.99, p=0.025) 0.69 (0.64-0.74, p<0.001)0.84 (0.77-0.93, p=0.001) 0.68 (0.64-0.74, p<0.001)
K Award (Time-Dependent)Yes9.42 (8.79-10.10, p<0.001)10.27 (9.54-11.05, p<0.001)

Summary

In these analyses of the outcomes of T32 post-doctoral trainees with MD, MD-PhD, and PhD degrees, we find that men with MD-PhD degrees had the highest rates for R01 application submission and award receipt (as PI). Women comprised a greater proportion of trainees over time. Serving as PI on a K-awards predicted a substantially higher rate of later support as PI on R01 awards.

I am grateful to my colleagues in the NIH Office of Extramural Research (OER) Division of Biomedical Research Workforce and Division of Statistical Analysis and Reporting for their help collecting these data and conducting these analyses.

This content was originally published here.

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