Residency Competency Assessments and Early-Career Primary Care Physicians' Antibiotic Prescribing.

Importance: Antibiotic prescribing varies across primary care physicians (PCPs) and disproportionately harms older adults, yet whether residency training is a factor in this variation is unknown. Objective: To evaluate whether PCPs' Accreditation Council for Graduate Medical Education (ACGME) competency ratings toward the end of residency are associated with their early-career pattern of antibiotic prescribing to older adults. Design, Setting, and Participants: This cohort study involved graduates of US ACGME-accredited internal medicine and family medicine residency programs between January 1, 2015, and December 31, 2020, who were in their first 5 years of primary care practice. Their ACGME Milestone ratings (hereafter competency ratings) were linked to Medicare Parts B and D public claims from January 1, 2015, to December 31, 2022. Data analysis was conducted between March 2024 and May 2026. Exposure: Overall competency rating in the middle of the final year of residency. Ratings for 22 subcompetencies (5-point developmental scale) were averaged within 6 core competency domains (patient care, medical knowledge, professionalism, interpersonal and communication skills, systems-based practice, and practice-based learning and improvement), averaged across domains, and then standardized at the residency program level. Main Outcome and Measure: Annual antibiotic prescription rate. This primary outcome was expressed as an incidence rate ratio (IRR) adjusted for physician, residency program, practice location, and patient-panel factors. Residency training program was examined as a secondary factor. Results: The analysis included 31 800 PCPs (mean [SD] age on practice entry, 32.8 [4.2] years; 15 990 females [50%]) who graduated from 1090 residency programs, representing 129 225 physician-years of prescribing data. Among these physicians, 58% graduated from a US medical school, 90% earned an MD degree, and 51% specialized in internal medicine and 49% specialized in family medicine. Each physician panel had a mean (SD) of 169 (144) Medicare beneficiaries per year (mean [SD] age, 70.3 [3.5] years; 59% female patients). Physicians prescribed a mean (SD) of 54.1 (52.2) antibiotics per year, and the full cohort wrote 7 664 372 antibiotic prescriptions across the study period. In unadjusted analyses, graduates from internal medicine and family medicine residency programs with highest vs lowest quintile prescribing rates prescribed a difference of 14.9 (95% CI, 13.8-15.9; P < .001) and 18.8 (95% CI, 17.9-19.7; P < .001) additional antibiotics per 100 beneficiaries per year, respectively. In adjusted analysis, each 1-SD increase in overall competency rating was associated with 0.7 (95% CI, 0.5-0.9) fewer antibiotic prescriptions per 100 beneficiaries per year (adjusted IRR, 0.98; 95% CI, 0.97-0.99; P < .001). Each year of experience was associated with higher antibiotic prescribing (IRR, 1.01; 95% CI, 1.01-1.02; P < .001), even accounting for the reduction in prescribing that occurred across study years. Conclusions and Relevance: This study found that higher assessed competence near the end of residency was associated with lower antibiotic prescribing in early primary care practice. Competency assessments may inform prescribing variation-focused efforts during training and early practice.