expand on this body of knowledge by analyzing a larger breadth of outcomes while factoring hospital, provider, and patient-level variables.METHODS: Patients who underwent NS between 2009 and 2014 were identified using ICD-9-CM codes from the Statewide Planning and Research Cooperative System database, a comprehensive all-payer reporting system that contains all hospital discharges in New York State. Data was supplemented with facility-level information from the American Hospital Association, provider-level information from the American Medical Association (AMA) Masterfile, and additional information from US Census data. Multivariable regression was used to assess the effect of hospital and physician volume, while adjusting for patient and hospital characteristics.RESULTS: 24,848 encounters involving NS were identified from 2009 to 2014 of which 22,848 could be matched to a surgeon and were used during the course of this study. These encounters occurred at 134 different facilities under the supervision of 557 unique surgeons. Of the total considered, 2,711 (11.9%) were readmitted within 90 days, 1,135 (5.0%) died within a year, and the median total charge was $35,520 (IQR; $26,579:$51,732). Every two-fold increase in physician caseload was associated with no significant change in 90-day readmission (OR 1.02 [0.99, 1.05]), an 11% decrease in prolonged stay (OR 0.89 [0.87, 0.91]), 7% decrease in 1-year mortality rate (OR 0.93 [0.90, 0.95]), and a 3% decrease in total charge (OR -0.03 [-0.04,-0.03]). Every two-fold increase in facility caseload was associated with no significant change in 90-day readmission (OR 0.98 [0.96, 1.02]), 10% decrease in prolonged stay (OR 0.90 [0.88, 0.93]), a 9% decrease in 1year mortality rate (OR 0.91 [0.87, 0.95]), and a 13% increase in total charge (0.12 [0.12, 0.13]).CONCLUSIONS: This study demonstrated that increasing physician caseload in nephrectomies is associated with benefits in decreasing rates of 1-year mortality and prolonged stay as well as lowering associated total charges. Increasing facility volume was associated with decreases in rates of 1-year mortality and prolonged stay, but increases in associated total charges.