An instrumental variable analysis of the impact of practice guidelines on improving quality of care and diabetes-related outcomes in the elderly Medicare population

Am J Med Qual. May-Jun 2008;23(3):222-30. doi: 10.1177/1062860608314940.


The effect of the diabetes practice guideline recommending >or=2 HbA1c tests annually on diabetes-related outcomes was evaluated using Medicare claims data. The study population included 1998 and 1999 incident diabetes patients aged >or= 67 years, who were Medicare eligible and without known diabetes-related complications at baseline. Number of HbA1c tests was measured 1 year after diabetes incidence. All-cause death and diabetes complications were identified during follow-up, through December 2003. The analysis was conducted with an instrumental variable method and a bivariate probit model, controlling for individual, social, and health care system characteristics. Among 13 033 patients, 27.1% followed the practice guideline. Receiving >or=2 HbA1c tests annually was significantly associated with a decrease in probability of 28.8 percentage points for macrovascular complications, 28.7 for atherosclerotic heart disease, and 23.1 for chronic kidney disease or end-stage renal disease in the 4-year follow-up period.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Diabetes Complications / epidemiology
  • Diabetes Mellitus / therapy*
  • Female
  • Glycated Hemoglobin A / analysis
  • Guideline Adherence / statistics & numerical data*
  • Humans
  • Insurance Claim Review
  • Male
  • Medicare / statistics & numerical data*
  • Practice Guidelines as Topic*
  • Quality of Health Care / statistics & numerical data*
  • United States


  • Glycated Hemoglobin A