Do MCAT, NBME, and UWorld practice exam scores help predict performance on USMLE Step 1?

  • Raza Hasan Sagarwala Saint Louis University School of Medicine


Background: The blueprint to matching into a top residency program has gone through much change over the past few decades, culminating to the current iteration that places strong emphasis on scores from the United States Medical Licensing Examination (USMLE) Step 1. Although current literature exists that demonstrates correlations between scores on the 1991 version of the Medical College Admission Test (MCAT), Comprehensive Basic Science Exam (CBSE), and USMLE Step 1, little focus has been placed on the predictive abilities of the 2015 MCAT, the Comprehensive Basic Science Self-Assessment (CBSSA) practice exams from the National Medical Board of Examiners (NBME), and self-assessments from the popular UWorld question bank.


Methods: The participants in this study are third year medical students who recently took the USMLE Step 1 exam and completed an online survey via Qualtrics. The survey asked students to accurately report their scores on the MCAT, scores from all CBSSA forms, scores from both self-assessments from UWorld, and USMLE Step 1 scores.


Results: Results from 87 third year medical students (49% of respondents) demonstrate an average Step 1 score of 238. Multiple linear regressions were performed on MCAT scores, CBSSA exam scores, UWorld self-assessment scores, and USMLE Step 1 scores in order to elucidate any potential relationships. These data demonstrated that Step 1 scores are strongly correlated to: UWorld self-assessment 2 (r=0.86, p<0.0001), CBSSA form 16 (r=0.83, p<0.0001), and UWorld self-assessment 1 (r=0.82, p<0.001). Alternatively, the lowest correlation to actual Step 1 scores was students’ performance on the 1991 version of the MCAT (r=0.17, p=0.01). Correlation to Step 1 was higher with the 2015 MCAT (r=0.52, p<0.001).


Conclusions: Our study suggest that the best predictor of performance on USMLE Step 1 are UWorld self-assessments 1 & 2 and CBSSA form 16. Conversely, the poorest predictor of performance on USMLE step 1 is the score received on the 1991 version of the MCAT. The 2015 MCAT seems to be a better predictor of academic success in medical school than the 1991 version of the MCAT.