How to Predict USMLE Scores From COMLEX-USA Scores: A Guide for Directors of ACGME-Accredited Residency Programs

Graduates of colleges of osteopathic medicine (COMs) frequently apply to residency programs approved by the Accreditation Council for Graduate Medical Education (ACGME).^1,2 These residency programs commonly use United States Medical Licensing Examination (USMLE) scores among their selection criteria.^3–5 Osteopathic medical students take the Comprehensive Osteopathic Medical Licensing Examination (COMLEX-USA) at the time USMLE is given, during the second and fourth years of medical school. Osteopathic medical students who apply to ACGME residency programs must either take USMLE in addition to COMLEX-USA or face a potential selection bias. A correlation between the two examinations would afford ACGME residency directors the opportunity to place osteopathic standardized tests into a frame of reference. In addition, it would allow a measure of confidence for COM students to understand how they compare with their allopathic counterparts. To our knowledge, ours is the first study to evaluate the correlation between scores on COMLEX-USA and scores on USMLE by COM students who took both examinations.

Methods

We analyzed the test scores of all students who took both COMLEX-USA Level 1 and USMLE Step 1 and those who took both COMLEX-USA Level 2 and USMLE Step 2. We compared scores using the Pearson correlation and regression analysis. The study was granted institutional review board exemption.

Results

The mean±SD scores were as follows: COMLEX-USA Level 1, 549±73; USMLE Step 1, 201±22; COMLEX-USA Level 2, 575±86; and USMLE Step 2, 200±22. The Pearson product moment correlation coefficient of the scores on COMLEX-USA Level 1 and USMLE Step 1 was 0.83 (P<.001), and for COMLEX-USA Level 2 and USMLE Step 2 was 0.70 (P<.001). The USMLE Step 1 score is predicted by the COMLEX-USA Level 1 score using the following equation:

The USMLE Step 2 score is predicted by the corresponding COMLEX-USA Level 2 score using the following equation:

Comment

Graduates of COMs make up an ever-increasing number of applicants to allopathic residency programs. From 1996–1997 to 1999–2000, the number of COM graduates filling allopathic residency programs rose 17.7%.¹ In the 2001–2002 academic year, 2316 COM graduates were in graduate medical education programs approved by the American Osteopathic Association, while 4658 were in ACGME-accredited programs.² Scores on USMLE are very influential in residency selection for allopathic programs.^3–5 Graduates of COMs must either apply for positions in allopathic medical residency programs using their COMLEX-USA scores or take USMLE in addition to COMLEX-USA. We have shown a correlation between the scores on COMLEX-USA Levels 1 and 2 and the corresponding scores on USMLE Step 1 and Step 2. Part of COMLEX-USA, unique to COMs, involves osteopathic theory and technique. It could be that differences in scores may relate to this additional content; however, the exact content of each examination was not available for comparison. A COM student's COMLEX-USA Level 1 and Level 2 scores can reasonably and accurately predict USMLE Step 1 and Step 2 scores. Our formulas provide a method of comparison for residency directors in ACGME-accredited institutions as they evaluate applicants from COMs. Further research is necessary to evaluate the use of these formulas on a prospective basis.