Investigating the Relationship Between a Clinical Science Composite Score and USMLE Step 2 Clinical Knowledge and Step 3 Performance

Previous research has found a moderate relationship between performance on individual clinical science subject examinations and USMLE performance. Given the widespread use of the clinical science subject examinations and the need for measures of clinical knowledge that help predict performance on Steps 2 CK and 3 and performance in residency training, this study explores the use of composite scores based on clinical science subject examinations to predict clinical knowledge outcome measures. The data set included students who took all of the five most widely used clinical science subject examinations (medicine, obstetrics and gynecology, pediatrics, psychiatry, and surgery) between January 1, 2013, and December 31, 2017 (N = 65,516). Composite scores were calculated based on average equated percent correct scores across various combinations of clinical science subject examinations. Stepwise linear regression analyses were performed with composite score and Step 1 score as predictor variables and Step 2 CK score or Step 3 score as the dependent variable. In all cases, the proportion of variance explained (R²) by the composite score (0.62–0.65 for Step 2 CK score and 0.45–0.48 for Step 3 score) was greater than R² for Step 1 by itself (0.52 for Step 2 CK score and 0.37 for Step 3 score). Logistic regression analyses found that higher composite scores were associated with a greater probability of passing Steps 2 CK and 3. Composite scores can be used alone or in conjunction with Step 1 to identify students at risk of failing Step 2 CK and/or Step 3 to facilitate remediation.