Objectives: Osteopathic medical students must take the Comprehensive Osteopathic Medical Licensing Examination (COMLEX)-USA series of examinations, but not the United States Medical Licensing Examination (USMLE-1) series. Few data are available describing the comparability of the two tests. This study sought to determine if COMLEX-1 scores could predict USMLE-1 scores among osteopathic medical students applying to an emergency medicine (EM) residency and to determine if the scores are interchangeable.

Methods: This was a retrospective analysis of osteopathic medical students applying to an EM residency program in the 2005-2006 and 2006-2007 application seasons. Students were included if they took both the COMLEX-1 and the USMLE-1 examinations. Linear regression was performed and a Bland-Altman plot of the standardized mean scores of each test was created.

Results: Ninety students were included. The mean (+/- standard deviation [SD]) COMLEX-1 score was 559.5 (+/-68.6), and the mean (+/-SD) USMLE-1 score was 207.6 (+/-15.5). The correlation was 0.79, with an R(2) of 62.3%. The Bland-Altman plot showed a mean difference between the standardized scores of 0, with 95% confidence intervals (CIs) of )1.28 to +1.28 standard normal units. Limitations include that this was a single center study, and only students who took both tests could be studied.

Conclusions: COMLEX-1 scores predict only 62.3% of the variance in USMLE-1 scores, and the scores are not interchangeable.