The relationship between hospital case mix, academic affiliation, program size, and American Board of Internal Medicine examination pass rates

Author Department

Internal Medicine; Medicine

Document Type

Article, Peer-reviewed

Publication Date

12-2025

Abstract

Background: American Board of Internal Medicine (ABIM) certifying exam pass rates are crucial metrics for internal medicine residency programs, as lower pass rates influence accreditation. Additionally, higher scores correlate with lower hospitalist-specific mortality and readmission rates. Prior research identified associations between pass rates and factors such as US Medical Licensing Examination scores and in-training examination performance. However, little is known about how residency training factors such as hospital patient complexity, academic affiliation, region, and program size affect ABIM pass rates. This study aimed to identify determinants of ABIM pass rates to serve as a reference for residency applicants and residency program leaders.

Methods: Data from 550 US internal medicine residency programs were analyzed, incorporating publicly available ABIM pass rates (2022-2024), hospital case mix index (CMI) as a surrogate for patient acuity, academic affiliation, geographic region, and program size. Descriptive and inferential statistics were performed using JASP software.

Results: The average ABIM exam pass rate for first-time test takers was 86% (standard deviation 11.7). University-based programs had significantly higher pass rates than community-based and community-based university-affiliated programs (F(2542) = 52.70; < 0.001). Pass rates correlated positively with hospital CMI (r = 0.34, P < 0.001) and program size (r = 0.272, P < 0.001), but not geographic region (P = 0.21). A regression model showed CMI, program size, and academic affiliation as significant determinants, explaining 22.5% of pass rate variance.

Conclusion: Higher patient acuity, university-based affiliation, and larger residency programs significantly correlate with higher ABIM pass rates. These findings provide insights for residency applicants upon selecting training programs. Further research is needed to evaluate these factors in relation to clinical competence.

Keywords: Board pass rate; case mix index; clinical acuity; internal medicine residency training.

PMID

41717358

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