Correlation of Medical College Admission Test Scores and Self-assessment Materials with the United States Medical Licensing Examination Step 1 Performance

: Purpose Candidates' performance on the United States Medical Licensing Examination (USMLE) Step 1 examination had been correlated with the Medical College Admission Test (MCAT). However, in 2015, a new MCAT format was released and its correlation with Step 1 remains to be fully analyzed. Preparation for Step 1 typically involves purchasing and perusing practice tests from the National Board of Medical Examiners (NBME) and UWorld; however, their predictive value to performance on Step 1 remains to be ascertained, especially with the release of five new NBME practice tests. Additionally, there is a need for accurately predicting Step 1 scores to self-evaluate study progress and reduce student anxiety. Rationale Program directors rank USMLE Step 1 scores as the number one criterion in selecting interviewees for residency. Step 1 scores are more important than Step 2 scores, Dean's letter, or other letters of recommendation in determining the overall ranking of a candidate after interviews. Hypotheses The authors hypothesized that the new MCAT scores correlated positively with Step 1 scores and that the new NBME practice tests were more predictive of performance on Step 1 as compared to old NBME tests.  Methods Linear regression analysis followed by either analysis of variance (ANOVA) or Student's t-tests were used to analyze 399 responses. Data obtained was used to update an existing Step 1 score predictor, which was then validated. Results A positive correlation between the MCAT (average score: 510.1 ± 6.3) and Step 1 scores (average score: 246.1 ± 14.2) was observed. While new NBME practice tests were more predictive of Step 1 scores than old NBME tests, UWorld test scores were the most predictive. Students who practiced with the new NBME practice tests scored significantly higher than students who did not use them. However, students using any of the UWorld practice tests did significantly better than students who practiced using only NBME practice tests but not UWorld practice tests. Ironically, NBME16,the second-most correlativetest to Step 1 performance, is no longer available for purchase. Overall, taking six or more practice tests significantly enhanced Step 1 scores; the optimal number of tests was found to be between six and nine. The predicted score by an updated Step 1 score predictor was within 3.8 points or 1.6% of the actual Step 1 score. Conclusions We believe this study will aid in the selection and purchase of appropriate self-assessment tests as preparatory material for the USMLE Step 1 examination. It will also introduce them to an existing Step 1 score predictor that will help determine their readiness for Step 1.