Strategies to reduce variation in the use of surgery.

Provision rates for surgery vary widely in relation to identifiable need, suggesting that reduction of this variation might be appropriate. The definition of unwarranted variation is difficult because the boundaries of acceptable practice are wide, and information about patient preference is lacking. Very little direct research evidence exists on the modification of variations in surgery rates, so inferences must be drawn from research on the alteration of overall rates. The available evidence has large gaps, which suggests that some proposed strategies produce only marginal change. Micro-level interventions target decision making that affects individuals, whereas macro-level interventions target health-care systems with the use of financial, regulatory, or incentivisation strategies. Financial and regulatory changes can have major effects on provision rates, but these effects are often complex and can include unintended adverse effects. The net effects of micro-level strategies (such as improvement of evidence and dissemination of evidence, and support for shared decision making) can be smaller, but better directed. Further research is needed to identify what level of variation in surgery rates is appropriate in a specific context, and how variation can be reduced where desirable.