title: Estimating physician effects on glycemic control in the treatment of diabetes: methods, effects sizes, and implications for treatment policy.
abstract: OBJECTIVE
  Researchers have only just begun to investigate physician-related effects on medical outcomes. Such research is necessary for developing empirically informed practice guidelines and policy. The primary goal of this study was to investigate whether glucose management in type 2 diabetes varies by randomly assigned physicians over the course of a year in treatment. A second goal of the study was to investigate whether physician-related effects vary across differential patient characteristics. A tertiary goal was to investigate potential patient-level effects on glucose management.
  
  
  METHODS
  Hierarchical linear models were used to investigate A1C among 1,381 patients, nested within 42 randomly assigned primary care physicians at a Veterans Affairs medical center in the southeastern U.S. The primary outcome measure was change in A1C over the course of 1 year in treatment. On average, each study physician had 33 patients with diabetes.
  
  
  RESULTS
  Overall, physician-related factors were associated with statistically significant but modest variability in A1C change (2%), whereas patient-level factors accounted for the majority of variation in A1C change (98%). Physician effects varied by patient characteristics, mattering more for black patients, patients aged 65 years, and patients whose glucose management improved over the treatment year.
  
  
  CONCLUSIONS
  The results of this study indicate that differential physician effects have minimal impact on glycemic control. Results suggest that it is logical to support policies encouraging the development of patient-level behavioral interventions because that is the level that accounts for the majority of variance in glycemic control.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA. tuerk@musc.edu
authors.forename: Peter W
authors.initials: PW
authors.lastname: Tuerk
authors.forename: Martina
authors.initials: M
authors.lastname: Mueller
authors.forename: Leonard E
authors.initials: LE
authors.lastname: Egede
mesh_terms: D000368:Aged; D001294:Attitude to Health; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism*; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000097:blood / Q000453:epidemiology / Q000523:psychology* / Q000628:therapy; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006787:Hospitals, Veterans; D006801:Humans; D008297:Male; D008875:Middle Aged; D010817:Physician-Patient Relations; D010821:Physicians, Family / Q000523:psychology; D015144:Southeastern United States; D014481:United States / Q000453:epidemiology; D044465:White People; D001741:Black or African American
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin