Background. Explanations for regional variation in the use of many medical and surgical treatments is controversial.
Objectives. To identify factors that might be amenable to intervention, we investigated the determinants of regional variation in the use of knee replacement surgery.
Research Design. 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.
Outcomes Measure. County utilization rates of knee replacement in Ontario, Canada.
Results. 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).
Conclusions. 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.