Effects of the allopathic and osteopathic graduate medical education merger on U.S. specialty training: a review

The Single Accreditation System (SAS) unified graduate medical education (GME) accreditation for allopathic (MD) and osteopathic (DO) programs under the Accreditation Council for Graduate Medical Education (ACGME). Implemented between 2015 and 2020, it aimed to expand access and standardize residency training across degree types. While the SAS succeeded in expanding opportunities for DO graduates in certain specialties, particularly family medicine and pathology, persistent disparities remain across competitive medical and surgical fields. Specialty-specific analyses reveal that DO applicants continue to face significant barriers in dermatology, ophthalmology, plastic surgery, neurosurgery, and orthopedic surgery, with disproportionately lower match rates and limited representation in top-tier residency programs. Structural challenges including the closure of many osteopathic-led programs, limited access to research mentorship, and degree-based bias among residency programs have exacerbated these disparities. Although Osteopathic Recognition and initiatives such as the Pathologist Pipeline have helped support osteopathic participation in select areas, broader reforms are needed to fulfill the original goals of the SAS. Enhancing academic partnerships, expanding research infrastructure, addressing implicit biases, and fostering DO leadership within academic medicine are critical steps toward ensuring equitable residency access for all graduates. Continued monitoring of match trends and specialty-specific outcomes will be essential to assessing the SAS's long-term impact on healthcare workforce diversity and equity.