Variation in medical practice: literature review and discussion

Variation in medical practice has become a major topic of inquiry for health services researchers. Investigators have frequently documented variation in the way in which health services are delivered, both among individual clinicians and across geographic areas, and have found that such variation often cannot be explained by demographic factors or other determinants of health need. The existence of such unexplained variation has provoked questions about the effectiveness, efficiency and quality of health care services. Observations of variation have consequently been used to justify a variety of policies aimed at reducing variability, such as greater emphasis upon outcomes research, feedback to practitioners, and closely monitored performance measures.