Re-evaluation of the methodology for estimating the US specialty physician workforce.

Increasing pursuit of subspecialized training has quietly revolutionized physician training, but the potential impact on physician workforce estimates has not previously been recognized. The Physicians Specialty Data Reports of the Association of American Medical Colleges, derived from specialty designations in the American Medical Association (AMA) Physician Professional Data (PPD), are the reference source for US physician workforce estimates; by 2020, the report for pathologists was an undercount of 39% when compared with the PPD. Most of the difference was due to the omission of pathology subspecialty designations. The rest resulted from reliance on only the first of the AMA PPD's 2 specialty data fields. Placement of specialty designation in these 2 fields is sensitive to sequence of training and is thus affected by multiple or intercalated (between years of residency training) fellowships. Both these phenomena have become progressively more common and are not unique to pathology. Our findings demonstrate the need to update definitions and methodology underlying estimates of the US physician workforce for pathology and suggest a like need in other specialties affected by similar trends.