Board certification practices of US hematologists and oncologists.

9034 Background: United States (US) fellowship programs train physicians in both hematology and medical oncology (HO), yet fellows often focus on only one of these specialties. Historically, single-subspecialty boarding has been viewed as a feasible career pathway for medical oncologists pursuing academic careers; single-boarding in hematology was uncommon while dual-boarding was favored for clinical practice. Real-world HO board certification practices and how these partition with career pathways are presently unknown. Methods: We linked Centers for Medicare & Medicaid Services (CMS) and American Board of Internal Medicine (ABIM) publicly available data to describe the credentialing practices of all US HO who billed Medicare Part B in 2022. Physicians were single-boarded (only obtained hematology or oncology certification) or double-boarded. Current position was dichotomized per CMS as teaching versus non-teaching hospital and metropolitan versus non-metropolitan per rural-urban commuting area codes (1-3 vs 4-10). Researchers had non-federal research funding in 2022 per CMS Open Payments while clinicians did not. Results: Of 12,394 physicians, 32% single-boarded in oncology, 3% single-boarded in hematology, and 64% double-boarded. Single-boarded hematologists were more frequently employed at teaching hospitals in metropolitan areas (Table). Researchers or those who graduated from a top 20 ranked medical school were more frequently single-boarded. Maintenance of certification was most common for those who initially double-boarded and least common for those who single-boarded in hematology. Physicians who maintained both boards or only oncology boards were most frequently clinicians at teaching hospitals while those who only maintained hematology boards were most frequently researchers at teaching hospitals. Conclusions: Over one-third of US HO fellowship graduates single board, with single-boarding in oncology being 10x more common than single-boarding in hematology. Single-boarded hematologists were more likely to work at teaching hospitals than single-boarded oncologists or dual-boarded physicians. Consideration could be given to tailoring US HO fellowship training requirements to more appropriately fit the interests and career pathways of HO fellows. Physician characteristics by initial ABIM hematology/oncology credentialing. Characteristic Oncology Single-Board, n=4,012 Hematology Single-Board, n=400 Hem/Onc Double-Board, n=7,982 p-value Female gender 1,402 (35%) 13 (34%) 2,878 (36%) 0.38 Years Since Medical School Graduation (SD) 28.8 (11.9) 29.8 (14.7) 25.0 (11.0) <0.001 Top 20 Medical School 641 (16%) 57 (14%) 645 (8%) <0.001 Teaching Hospital 3,317 (83%) 361 (90%) 6,549 (82%) <0.001 Metropolitan Area 3,777 (94%) 388 (97%) 7,508 (94%) 0.04 Non-Federal Research Funds 1,586 (40%) 156 (39%) 2,602 (33%) <0.001 Maintenance of Certification 2,859 (71%) 252 (63%) 6,450 (81%) <0.001