Letters to the Editor  |   July 2010
New COMLEX-USA-to-USMLE Conversion Formula Needed
Author Affiliations
  • Carly A. Shiembob, DO
    St. Joseph's Regional Medical Center, Paterson, NJ
    Aria Health System, Philadelphia, PA
Article Information
Medical Education / Graduate Medical Education / COMLEX-USA
Letters to the Editor   |   July 2010
New COMLEX-USA-to-USMLE Conversion Formula Needed
The Journal of the American Osteopathic Association, July 2010, Vol. 110, 400-401. doi:
The Journal of the American Osteopathic Association, July 2010, Vol. 110, 400-401. doi:
To the Editor:  
Clinical rotations during the third and fourth years of osteopathic medical school have provided each of us with invaluable experience in medicine. However, we obtained something even more valuable from our discussions with attending physicians—both DOs and MDs—regarding the residency application process. A common theme from these conversations was the standardized testing system in osteopathic medicine. 
We were often questioned about our reasons for taking both the United States Medical Licensing Examination (USMLE) and the Comprehensive Osteopathic Medical Licensing Examination (COMLEX-USA). Our reasons for doing so consisted of two layers. The superficial layer concerned the rules and regulations of Accreditation Council for Graduate Medical Education (ACGME) residency programs, which we were each interested in pursuing. Many of these programs require successful completion of Step 1 and Step 2 of the USMLE in order to be considered for an interview. This requirement might be changed with revised rules and regulations, but the deeper layer of our reasons for taking both the USMLE and COMLEX-USA would remain. 
The deeper layer of our reasoning seemed to strike home with the attending physicians. This layer concerned comparison of examination scores. How does a director of an ACGME residency program compare an osteopathic medical student's COMLEX-USA score with an allopathic medical student's USMLE score? In the September 2006 issue of JAOA—The Journal of the American Osteopathic Association, Dr Philip C. Slocum and Janet S. Louder1 reported formulas for estimating USMLE Step 1 and Step 2 scores from, respectively, COMLEX-USA Level 1 and Level 2 scores. However, when we examined these formulas, we realized why ACGME program directors who are unfamiliar with the COMLEX-USA would require a USMLE score from all applicants. 
The formulas as reported by Slocum and Louder1 are as follows:  
\[\mathrm{USMLE\ Step\ 1}=67.97+0.24{\times}\mathrm{COMLEX-USA}{\ }\mathrm{Level\ 1}(R^{2}=0.68)\]
\[\mathrm{USMLE\ Step\ 2}=102.2+0.18{\times}\mathrm{COMLEX-USA}{\ }\mathrm{Level\ 2}(R^{2}=0.46)\]
Using the first formula, a score of 500 on the COMLEX-USA Level 1 (which would be in the 50th percentile of scores) is equivalent to a score of 188 on the USMLE Step 1. Based on a simple z-score table and a standard deviation of approximately 20 on Step 1 of the USMLE (which has an average score between 200 and 2202), a score of 188 corresponds to the 5th percentile. 
These numbers would lead an ACGME program director who is trying to convert a COMLEX-USA score into a USMLE score to rightfully assume that an average score on the COMLEX-USA is equivalent to a score in the fifth percentile on the USMLE. Thus, the formula proposed by Slocum and Louder1 does not provide these program directors with an accurate view of osteopathic medical student qualifications. 
Until a larger study presents a more useful method for converting standardized testing scores, ACGME program directors will continue to withhold interviews from qualified osteopathic medical students—unless those students also have USMLE scores to report. Instead of trying to force ACGME programs to accept COMLEX-USA results, we believe it is more important for the osteopathic medical profession to develop a formula for examination score conversion that will more accurately reflect the qualifications of osteopathic medical students. 
Slocum PC, Louder JS. How to predict USMLE scores from COMLEX-USA scores: a guide for Directors of ACGME-accredited residency programs. J Am Osteopath Assoc. 2006;106(9):568-569. Accessed June 3, 2010.
FAQs. United States Medical Licensing Examination Web site. Accessed June 7, 2010.