Over the last quarter century, the number of IMGs in the United States grew on average by 4,873 per year reaching a total of 215,576 in 2004, about 2.4 times its 1978 size. The 2 subgroups of resident IMGs and practicing physician IMGs showed similar increases. In 2004, compared with USMGs, IMGs were older, less likely to be board certified, less likely to work in group practice, more likely to have Internal Medicine as practice specialty, and more likely to be residents.
This study has two major strengths. First, we used a dataset that is compiled using a systematic and comprehensive methodology and accounts for all active physicians licensed to practice medicine in the United States.21
Second, while other studies have provided a cross-sectional analysis of the reliance of the United States physician workforce on IMGs, we were able to describe the historical trends of IMGs in the United States over a period of more than 26 years. While the longitudinal analysis is unique to date, our analysis also reduces the possibility of chance findings that cross-sectional analysis are prone to, and more importantly, enables policymakers to make better future predictions.
The study has some limitations. We did not have the full population data available for analyzing physicians’ characteristics, and used instead, 2 samples of 1,000 records each based on a priori power calculations. IMGs include the two distinct subgroups of United States citizens who trained abroad and non-U.S. citizens. We did not describe the historical trends for the two aforementioned subgroups nor did we compare their characteristics. We did, however, adjust for U.S. citizenship status in comparing the characteristics of IMGs and USMGs. The linear models we used to depict the time trends of numbers and proportions might not be as strong as methods such as piecewise linear regression models or smooth spline models particularly for short-term fluctuations. However, the models we used are appropriate for the purpose of detecting long-term trends especially because they appear to be reasonably approximated by straight lines.
There are a number of interesting observations related to these historical trends. First, the actual numbers of IMGs show higher growth rates than their proportions (Figs. and ). This is explained by the fact that the growth in numbers is mainly related to the growth of the total population of active physicians in the United States (i.e., even if the proportions of IMGs remained constant, their number will still grow with the growth of the total population of physicians). Second, while the growth in the proportion of IMGs is greater for residents than for practicing physicians (0.38% vs 0.08%, respectively), the growth in the number of IMG residents is lower than for practicing physician IMGs (702 vs 4171, respectively). This is because of the fact that the total population of residents is much smaller than that of practicing physicians. The slower growth in the number of resident IMGs is also related to the fact that individuals joining the resident IMGs group will leave it after a few years (e.g., 3 years for Internal Medicine training) while individuals joining the practicing physician IMG group will leave it after many years of practice.
The comparisons of the characteristics of IMGs and USMGs are consistent with the published literature. In terms of board certification, Benson et al. found that among physicians who graduated between 1975 and 1980 and applied for the certifying examination of the American Board of Internal Medicine, USMGs had higher passing rates than IMGs.23
Among IMGs, non-U.S. citizens had higher passing rates than U.S. citizens. Norcini et al. showed similar results among 1958–1994 medical graduates, regardless of specialty.24
In terms of primary employer, Freshnok et al. also found in the early 1980s that physicians in group practice were predominantly USMGs.25
In terms of practice location, both a 1995 study and a 2003 study indicated that patterns of location of IMGs mirrored those of USMGs.26,27
Our findings relating to practice specialty differ from the findings by Mullan in 1995 that IMGs had similar specialty patterns to USMGs. The reasons for these differences are unclear.
Our analysis shows that over the last quarter century, the IMGs provided a significant and steady supply for the United States physician workforce. Based on the regression model, and assuming demand and supply factors remain the same, the number of IMGs would increase about 102,000 by 2025. In formulating policies to address the projected physician shortage, U.S. and foreign policymakers need to consider whether IMGs could sustain such supply. In fact, a number of high income countries are trying to address their own physician shortages by recruiting from the same pool of English-speaking IMGs as the United States.28
This competition could potentially complicate the recruitment of IMGs into the United States physician workforce and affect the quality of care delivered by those who are ultimately recruited.
In addition, the United States and foreign policymakers should consider the implications of the global physician migration for the ‘source countries’ that are mainly low income countries.29
These countries benefit financially through remittances, skills transfer, and possible investment upon migrants’ return.30
They suffer, however, from a ‘brain drain’ resulting in loss of educational investment, loss of intellectual capital, reduced range of available services, and chronic understaffing of health care facilities.31
This dilemma has indirect impact on high income countries such as the United States because of the increased threat of global pandemics. Public health in high-income countries increasingly depends on the effectiveness of health care systems in the low income countries.18
In summary, this study shows that the United States physician workforce increasingly consists of IMGs and that their characteristics differ from those of USMGs. Future studies should quantify the needs of the United States physician workforce for IMGs and determine how to meet those needs in view of the source countries’ requirements and the expected toll of the brain drain. Studies should also compare the quality of care provided by IMGs to that of USMGs and how the differences in certain characteristics of IMGs and USMGs (e.g., specialty and primary employer) affect clinical practice patterns.