Physical Limits to AI Substitution across Physician Specialties - Implications for the Physician Workforce

AbstractAI can already interpret medical images, draft diagnostic assessments, and converse with patients - fueling predictions that it will replace physicians. Yet software cannot physically examine, biopsy, or operate on a patient, so the share of a specialty's work that requires in-person physical interaction sets a ceiling on how much of it AI alone could replace. Analyzing 2023 Medicare Part B claims - nearly US$45 billion in payments to 589,648 physicians across 56 specialties - we classify each billed service by whether it requires physical contact, setting aside evaluation and management (E&M) visits. The share of non-E&M work that is physical, and thus protected at present from AI substitution, varies widely across specialties and increases in the length of postgraduate training: Procedural fields such as dermatology and orthopedic surgery are largely shielded. Only about one fifth of all payments go to non-E&M services with no physical barrier to AI substitution. Physicians, however, concentrate in E&M-heavy specialties - family and internal medicine - where physical protection, as we measure it, is low. The fields most accessible as career paths and most needed to relieve primary care shortages thus face the greatest uncertainty, because AI could impact their work as either a substitute or a complement - an outcome shaped as much by how AI is designed, deployed, and reimbursed as by the technology itself.