For more than thirty years, John Wennberg and his colleagues have been documenting variations in patterns of health care use from one community to the next, which are not explained by illness or demographic patterns. Twenty years ago Health Affairs devoted an issue to a symposium on this work, and it is striking how little some things have changed in the intervening years. In fact, there have been enormous changes in physicians' behavior and patterns of medical practice, but our cost problems seem as intractable as ever, perhaps because policymakers continue to focus erroneously on the relationship between use and costs.
