Explanations for regional variation in the use of many medical and surgical treatments is controversial.
To identify factors that might be amenable to intervention, we investigated the determinants of regional variation in the use of knee replacement surgery.
We examined the effect of the following factors: characteristics and opinions of surgeons; family physicians and rheumatologists; patients' severity of disease before knee replacement; access to knee-replacement surgery; surgeons' use of other surgical treatment; and county population characteristics.
County utilization rates of knee replacement in Ontario, Canada.
Counties that had higher rates of knee replacement had older patients (P = 0.0001), higher percentage of medical school affiliated hospital beds (P = 0.04), with more male (P = 0.02) non-North American trained referring physicians (P=0.002) and orthopedic surgeons who had higher propensities to operate and better perceptions of outcome (P = 0.0001).
After controlling for population characteristics and access to care (including the number of hospital beds, and the density of orthopaedic and referring physicians), orthopaedic surgeons' opinions or enthusiasm for the procedure was the dominant modifiable determinant of area variation. Thus, research needs to focus on the opinions of surgeons which may be important in reducing regional variation for knee replacement.
*From the Clinical Epidemiology and Health Care Research Program and Department of Surgery and Public Health Sciences, Division of Orthopaedic Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
†From the Clinical Epidemiology and Health Care Research Program, Division of Rheumatology, Department of Medicine, Women's College Hospital, University of Toronto, Toronto, Ontario.
‡From the Clinical Epidemiology and Health Care Research Program, Division of Rheumatology, Department of Medicine, Wellesley Central Hospital, University of Toronto, Toronto, Ontario.
§From the Clinical Epidemiology Unit, Sunnybrook & Women's College Hospital Health Sciences Centre, North York, Ontario, Canada.
#From the Division of General Internal Medicine, Vanderbilt University Medical Center, Department of Medicine, Vanderbilt University, Nashville, Tennessee.
**From the Bowen Research Center, Indiana University, Indianapolis, Indiana.
††From the Department of Health Administration and Institute for Policy Analysis, University of Toronto, Toronto, Ontario and Institute for Clinical Evaluative Sciences.
Supported by the US Agency for Health Care Policy and Research (06432).
This research was presented in part at the Canadian Orthopaedic Association Meeting in Ottawa, June 1998.
Dr. Hawker holds a Medical Research Council of Canada Scholar Award.
Dr. Wright is the RB Salter Chair in Surgical Research and is supported as a Scientist of the Medical Research Council of Canada.
Address correspondence to: James G. Wright, MD, MPH, Division of Orthopaedic Surgery, The Hospital for Sick Children, 555 University Avenue, Toronto ON M5G 2X4, Canada. E-mail: firstname.lastname@example.org
Received November 4, 1998; initial review completed December 18, 1998; accepted March 25, 1999.