Physician Composition of Hospitals’ Workforce and Mortality Across US Hospitals: A Cross-Sectional Study

Background: The inpatient clinical workforce in US hospitals is evolving, with advanced practice practitioners—nurse practitioners and physician assistants—playing increasingly prominent roles. The relationship between hospital clinician mix and patient mortality remains unclear. Our objective was to examine the association between hospital-level physician proportion and 30-day risk-standardized mortality rates (RSMRs) for common inpatient conditions. Methods: We conducted a cross-sectional national study of US hospitals treating Medicare fee-for-service beneficiaries in 2022. Medicare and American Hospital Association datasets were linked at the hospital level. The hospital-level exposure was the physician proportion, defined as affiliated physicians divided by total affiliated physicians and advanced practice practitioners. Outcomes were hospital-level RSMRs for acute myocardial infarction, coronary artery bypass graft surgery, chronic obstructive pulmonary disease, heart failure, pneumonia, and stroke. Results: Among 3487 hospitals, the mean physician proportion was 79.7% (standard deviation, 9.4%), ranging from 67.8% in the lowest quartile to 91.6% in the highest. Hospitals in the highest physician proportion quartile (Q4) had lower RSMRs than hospitals in the lowest quartile (Q1) for all conditions—acute myocardial infarction (12.54 versus 12.86; P < 0.001), coronary artery bypass graft (2.92 versus 3.05; P = 0.106), chronic obstructive pulmonary disease (9.11 versus 9.83; P < 0.001), heart failure (11.24 versus 12.73; P < 0.001), pneumonia (17.51 versus 18.64; P < 0.001), and stroke (13.41 versus 14.31; P < 0.001). Weighted multivariable models identified significant inverse associations between physician proportion and RSMRs. Conclusions: Greater physician representation was associated with lower hospital-level mortality across common and high-burden medical conditions, indicating workforce composition may be an important determinant of hospital quality.