Jun 2001

Disparity in Health: Is Geography Destiny?

Audiey Kao, MD, PhD
Virtual Mentor. 2001;3(6):215-216. doi: 10.1001/virtualmentor.2001.3.6.dykn1-0106


  • Small area analysis, a methodology for assessing health care utilization rates across geographic areas, was pioneered by Dr. John Wennberg, the Peggy Y. Thomson Professor of the Evaluative Clinical Sciences at Dartmouth Medical School. Nationally and internationally recognized in medical epidemiology, Dr. Wennberg's work has catalyzed a whole new field of inquiry in the examination of geographic variations [1] in the utilization of medical services such as cardiac catheterization/angioplasty [2-4], diabetic amputation [5], and orthopedic surgical procedures [6].
  • According to the Dartmouth Atlas of Health Care 1999, initially created by Dr. Wennberg to chronicle geographic variation in health care utilization, the rate of cardiac bypass graft surgery (CABG) was 5.4 per 1,000 Medicare enrollees living in Gainesville, Florida, while it was 9.4 per 1,000 Medicare enrollees living in Hudson, Florida, approximately 120 miles from Gainesville.
  • This variation in CABG rates between two Florida communities relatively close to each other persists even after potential explanatory factors including the health profile and status of patients are adjusted for. This variation in care may be secondary to a variety of factors, including patient preferences, local practice norms, and economic and market incentives. Some of these factors may not be valid reasons for the decision to perform or not perform a CABG, and thus may indicate either an overuse or underuse of such medical services.
  • Given that, on average, a Medicare patient in Gainesville is more likely to get a CABG than a Medicare patient in Hudson, it is critical that efforts be made to assess the outcome implications of such geographic variations in care. In other words, what is the "right" rate for coronary artery bypass surgery? Without this information, we cannot adequately address these variations in care, and, in terms of disparities in health, geography may well end up being destiny.


  1. Wennberg JE. Understanding geographic variations in health care delivery. N Engl J Med. 1999;340(1):52-53.
  2. O'Connor GT, Quinton HB, Traven ND, et al. Geographic variation in the treatment of acute myocardial infarction: the Cooperative Cardiovascular Project. JAMA. 1999;281(7):627-633.
  3. Mirvis DM, Graney MJ. Variations in the use of cardiac procedures in the Veterans Health Administration. Am Heart J. 1999;137(4 Pt 1):706-713.
  4. Wrobel JS, Mayfield JA, Reiber GE. Geographic variation of lower-extremity major amputation in individuals with and without diabetes in the Medicare population. Diabetes Care. 2001;24(5):860-864.
  5. Guadagnoli E, Hauptman PJ, Ayanian JZ, Pashos CL, McNeil BJ, Cleary PD. Variation in the use of cardiac procedures after acute myocardial infarction. N Engl J Med. 1995;333(9):573-578.
  6. Vitale MG, Krant JJ, Gelijns AC, et al. Geographic variations in the rates of operative procedures involving the shoulder, including total shoulder replacement, humeral head replacement, and rotator cuff repair. J Bone Joint Surg Am. 1999;81(6):763-772.


Virtual Mentor. 2001;3(6):215-216.



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