There has been a dramatic change in the physician workforce of academic health centers (AHCs) as increasing numbers of faculty have sought positions that afford opportunities for work–life balance. Some faculty seek part-time academic appointments, that is, positions with less than 1.0 full-time equivalent (FTE) effort.1–4 Women report a desire for part-time appointments more often than men do,2,3 commonly in response to the need to balance multiple personal and professional roles with the often-rigid requirements of medical schools.1 Academic department leaders must be prepared, therefore, to address issues of equity for part-time faculty and develop strategies for ensuring fair compensation and providing opportunities for academic advancement. However, little is known about equity in settings with increasing proportions of part-time faculty because previous studies examining pay equity and academic advancement for various groups have used data that predate the move toward part-time appointments or have not taken part-time appointments into account.5–10 Thus, we designed this study to identify whether equity in compensation and professional advancement exists in an academic pediatrics department in which a large proportion of the faculty hold part-time appointments.
Setting and participants
We conducted this study in April 2010 in the Vanderbilt University School of Medicine Department of Pediatrics, using data from July 1, 2007 through June 30, 2008. This department includes faculty who conduct research, teaching, and clinical service activities in a 223-bed freestanding children's hospital. Faculty may choose part-time appointments, and those who hold an appointment of at least 0.50 FTE or greater are entitled to the same rights and privileges as full-time faculty, including access to space, benefits, and representation in departmental decision making. Several leadership positions in the department were held by faculty with part-time appointments at the time of the study (residency program director, division chief, and medical student clerkship director).
We included physician faculty (faculty with MD or MD/PhD degrees) who were employed full-time (1.0 FTE) or part-time (<1.0 FTE) throughout the study year with a primary appointment in the department at the rank of assistant professor, associate professor, or professor. We restricted our analysis to physician faculty on the physician–scientist or clinician–educator track. We excluded physician faculty who were on the research track with no clinical component to their compensation. We did not include PhD faculty because of their small number and the different compensation structures for MD versus non-MD faculty.
Physician–scientists typically spend the majority of their professional effort in research and teaching and are either tenured or on the tenure track with a nine-year probationary period. Those with part-time appointments are given additional time during the probationary period to achieve promotion and tenure. Clinician–educators spend the majority of their professional effort in teaching and service and do not have a probationary period for promotion.
We obtained data from a departmental faculty database (sociodemographics and academic history), a financial database (compensation and clinical productivity defined using relative value unit [RVU] generation), and a research database (grant activity). These data were compiled and deidentified by medical school staff members who were not involved in the conduct of this study. We reviewed only deidentified data.
We designated total faculty compensation and years at assistant professor rank as the study outcomes. To determine each faculty member's compensation for the study year, we included base salary, additional pay (clinical pay, administrative supplements), and a Vanderbilt School of Medicine retirement supplement (5% of base pay, provided for all faculty). We adjusted base salary and the retirement supplement for FTE effort by dividing compensation by individual faculty FTE effort.
To determine years in rank for each faculty member, we calculated years as an assistant professor as the difference between the date of appointment to associate professor and the date of appointment to assistant professor (at any institution), or as the difference between the end of the study period and the date of appointment to assistant professor if the rank of associate professor had not been reached. Similarly, we calculated each faculty member's years as an associate professor as the difference between the date of appointment to professor and the date of appointment to associate professor (both at any institution), or as the difference between the end of the study period and the date of appointment to associate professor if the rank of professor had not been reached.
Study variables included demographic characteristics (gender, age, marital status, and race or ethnicity), academic appointment type (FTE status, rank, and track), academic history (year that MD or MD/PhD was obtained, year of first appointment as an assistant professor at any institution, year of first appointment to study institution, and whether the faculty member moved from another institution), clinical productivity (RVU generation in fiscal year 2008 divided by FTE effort), and grants activity (activity as principal investigator or coinvestigator on a research grant with effort support during the study year).
We summarized the distributions of the study variables for physician faculty overall and by FTE status (part-time or full-time). We summarized the distributions of continuous variables in terms of the median and the lower and upper quartiles. We summarized discrete variables in terms of frequencies and percentages. We used nonparametric Wilcoxon rank-sum and Pearson chi-square tests (the latter without a continuity correction) to determine whether there were differences in the distributions of both the outcomes and the study variables by FTE status.
We used ordinary least squares (OLS) regression analysis to determine the adjusted effects (direction and magnitude) of gender, rank, years since first appointment as an assistant professor (at any institution), clinical productivity (RVUs), FTE status, and track on predicting FTE-adjusted compensation. We divided years since first appointment as an assistant professor into groupings based on rounded values of the mean and median years. We transformed compensation to the natural logarithm of compensation to improve the fit and the predictive ability of the regression model. For partial control of overfitting in both regression models, the specific subset of covariates we chose took into account the “limiting sample size,” which we defined as the number of faculty members included in the analysis. We used restricted cubic splines, which allow continuous data to fit within a regression model without assuming a linear relation, to better approximate the true relation between continuous covariates (e.g., years since first appointment) and compensation.
In turn, we estimated the effects of years since first appointment and RVUs for specific intervals across their range because of their nonlinear effect on the log of FTE-adjusted compensation. In addition, using log-transformed dependent variables allows the estimated coefficients to be interpreted in terms of percent change. That is, the dependent variable changes by 100*(coefficient) percent for a one-unit increase in an independent variable while all other variables in the model are held constant.
We summarized years as an assistant professor and years as an associate professor across FTE status among those faculty holding appointments during the study period as assistant professors, associate professors, or professors. Each of these faculty groups (assistant professor, associate professor, and professor) was further divided by track (clinician–educator or physician–scientist). We used nonparametric Wilcoxon rank-sum tests to determine whether there were differences in the distributions of years in rank (assistant professor and associate professor) within each of these faculty groups and tracks according to FTE status (part-time or full-time). We used OLS regression analysis to determine the adjusted effects of gender, rank, FTE status, and track on predicting years as an assistant professor.
We considered P values less than .05 to be statistically significant, and all tests were two-sided. We report 95% confidence intervals for all point estimates. We performed statistical analyses using the R statistical software.11
This study was reviewed by the Vanderbilt University institutional review board and was considered to represent nonhuman subjects research because the data were anonymized prior to analysis by a third party not involved in the research. It was not possible to identify individuals in any of the data sets used to conduct the study.
Of the 119 physician faculty in the pediatrics department, 112 (94%) met the inclusion criteria. (Seven physician faculty were on the research track with no clinical component to their compensation and were thus excluded.) Among these 112 faculty, 23 (21%) held part-time appointments and 89 (79%) held full-time appointments. Demographic characteristics, academic appointment information, academic history, and clinical and grants activity for faculty by part-time versus full-time status are provided in Table 1.
Part-time faculty were more likely than full-time faculty to be women (17/23 [74%] versus 25/89 [28%], P < .001) and married (23/23 [100%] versus 75/89 [84%], P = .042). Part-time and full-time faculty did not differ significantly by median age (P = .667), race (P = .718), or ethnicity (P = .137). Whereas the distribution of rank did not differ significantly between part-time and full-time faculty, 20/23 (87%) of part-time faculty were on the clinician–educator track compared with 62/89 (70%) of full-time faculty, though this difference was not statistically significant.
There were no significant differences between part-time and full-time faculty with respect to academic history, including the year the MD or MD/PhD was obtained, the year of first appointment as an assistant professor, the year of first appointment to the study institution, and whether faculty had moved from another institution. There were no significant differences between part-time and full-time faculty in FTE-adjusted clinical productivity during the study year, the number of grants as principal investigator, or the number of grants with supported effort.
Although there were significant differences between part-time and full-time faculty for median FTE-adjusted compensation in the unadjusted analysis (P = .003; data not shown), part-time status was not a significant predictor of compensation in the multivariate models controlling for rank, gender, faculty track, years since the first appointment as an assistant professor, and clinical productivity (Table 2). Faculty rank and clinical productivity were significant predictors: The compensation of a professor was 65% higher (95% confidence interval, 48%–82%) than that of an assistant professor when adjusting for all other effects.
Time in rank
As reported above, our analyses demonstrated no difference in adjusted models for compensation by part-time versus full-time status but did indicate strong differences by rank. Our additional analyses examined the years in rank as an assistant professor to assess whether faculty with part-time appointments spent more time in lower academic ranks. Part-time faculty who were assistant professors during the study period had been in that rank for a mean of 9.07 years and a median of 7.87 years, whereas full-time faculty who were assistant professors had been in the rank for a mean of 4.92 years and a median of 3.95 years (Table 3). However, the differences in time in lower rank by part-time status were not statistically significant for faculty at any level. In the multivariate model, part-time status did predict more time in lower ranks in that part-time faculty spent on average 2.48 years longer as an assistant professor than did full-time faculty (95% confidence interval, 0.23–4.73 years) (Table 4). Faculty rank was a significant predictor of years spent as an assistant professor in that faculty who had been promoted were significantly more likely to have spent less time as an assistant professor than those faculty who had not been promoted.
In our study of the Vanderbilt University School of Medicine Department of Pediatrics, in which 21% of the overall physician faculty and 40% of the women physician faculty held part-time academic appointments, we found no evidence of inequity in compensation by part-time faculty status when adjusting for other predictors of compensation. We also found no evidence that part-time faculty were less productive in terms of clinical and research grant activity, which plays a prominent role in faculty compensation. We did find that faculty with part-time appointments spent longer times in the assistant professor rank.
Finding no difference in faculty compensation and objective measures of productivity between part-time and full-time physician faculty is important. AHCs may implicitly or explicitly provide fewer rewards for part-time faculty if it is perceived that they are less committed to their careers or to the mission of their department or medical school than their full-time counterparts are.12 This did not seem to be the case in the current study.
Previous studies of part-time faculty have suggested that, as a group, they may be less productive than full-time faculty. For example, in a recent survey-based study of general internal medicine faculty, Levine et al13 found that faculty with part-time appointments were less likely to have grant support and produce publications. That study relied on self-report, whereas we used objective measures of productivity. As noted above, we did not find any difference between part-time and full-time faculty in terms of clinical productivity and participation in grant-funded research.
We did find that faculty with part-time appointments in this study spent an average 2.48 years longer in the junior ranks than full-time faculty did. Given that rank is one of the strongest predictors of compensation, this finding is important. However, the fact that it took part-time faculty 2 to 3 years longer to achieve promotion may be reasonable. In the department studied, part-time faculty held several leadership positions during the study period, including division chief, residency program director, and medical student clerkship director. Thus, the proportion of faculty with part-time appointments and the appointment of part-time faculty to leadership positions suggest a culture that may be accepting of these faculty and supportive of their career development.
As more academic physicians choose part-time appointments, efforts to ensure equity must be explicit. This study highlights issues that should be addressed when studying and addressing equity and provides a model for other institutions. For example, studies of pay equity and time in rank should determine whether faculty track and voluntary part-time appointments affect career trajectories. Given the historical gender inequities in compensation5–7,9 and the larger proportion of women choosing part-time appointments, the effect of gender should always be considered as well. It is likely that the relationship between percent effort and academic progress is nonlinear. Thus, further research to understand specific details of academic progress for faculty with part-time appointments is warranted. It would be helpful to assess whether part-time faculty in fact spend relatively more hours per week engaged in professional activities than full-time faculty do. In addition, studies should address whether there are differences in mentoring about academic expectations for faculty with part-time appointments and whether other circumstances specific to part-time faculty affect professional advancement and compensation.
Whereas the strengths of the study include our use of institutional databases rather than self-report data, consideration of clinical and research productivity, and inclusion of all physician faculty in the department, there are several important limitations. We conducted the study in a single institution, with a small sample size and, therefore, inherent issues of generalizability. However, we were able to demonstrate a difference in time in junior rank, and our models included several important predictors of compensation and academic advancement. It is possible that a faculty member's part-time status may change over time, so a longitudinal study would be needed to provide a more comprehensive understanding of the effect of part-time academic appointments on advancement. That said, there are likely to be important consistencies across the study institution and other large AHCs which may provide important insight to decision makers for departments in which large proportions of faculty choose part-time appointments.
This study highlights several critical issues related to part-time physician faculty in academic departments. The findings of this study suggest that part-time and full-time faculty are comparable in several objective measures of productivity. Part-time faculty do spend longer times in junior ranks, but this difference is not unexpected. Given the increasing numbers of faculty choosing part-time appointments, departmental leaders should implement strategies to encourage their career advancement, such as providing appropriate mentoring resources to meet academic expectations, opportunities for networking, flexible work schedules, and monitoring of metrics for promotion. This study provides a useful model which can be used to assess equity for faculty at particular points in time as well as to evaluate trends over time.
The authors acknowledge the support of Jonathan D. Gitlin, MD, who provided financial support for the programming, statistical analysis, and data entry required for the study, as well as invaluable assistance in reviewing the manuscript.
The study was reviewed by the Vanderbilt University institutional review board and was considered to represent nonhuman subjects research.
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© 2011 Association of American Medical Colleges
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