Revisiting the Utility of the National Board of Medical Examiners Comprehensive Basic Science Self-Assessment to...

The National Board of Medical Examiners^® Comprehensive Basic Science Self-Assessment (CBSSA) is a 200-item web-administered multiple-choice examination built to the same test specifications in content and statistics as the United States Medical Licensing Examination^® Step 1 to help students assess their readiness and familiarize themselves with the content and format of Step 1. This study investigated the relationship between last-attempt CBSSA scores and first-attempt Step 1 pass-fail outcomes based on a large and recent sample of 23,271 US and Canadian medical students who took CBSSA under standard timing conditions between February 23, 2022 and March 1, 2023 and subsequently took Step 1 for the first time under standard timing conditions. The number of CBSSA attempts, when students took CBSSA in relation to their first Step 1 attempt, and the interaction between the different levels of these two factors were investigated. Separate binary logistic regressions were performed with last-attempt CBSSA score as the independent variable and first-attempt Step 1 pass-fail outcome as the dependent variable for the entire study group as well as sub-groups who took Step 1 within 1-2 weeks, 3-4 weeks, 5-6 weeks, and over 6 weeks of their last CBSSA attempt. All models were statistically significant. The relationship between the last CBSSA and first Step 1 was statistically different across the different time intervals, except for those within 5-6 weeks and over 6 weeks. The highest classification accuracy was for students testing within 1-2 weeks. Results suggest that CBSSA remains an effective tool to gauge readiness for Step 1.