Regional Variations in Diagnostic Practices

Risk adjustment is an essential element of comparative-effectiveness studies, measurements of health care performance, and payment programs and is destined to become even more important as health care reform proceeds. Observational studies comparing the outcomes of various approaches to treatment1 or the performance of specific providers often adjust for patients' preexisting diagnoses.2 The Medicare payment systems for institutional providers and health plans include payment adjustments that take into account the beneficiaries' health or functional status.3,4 As payers move toward more bundled and value-based payment systems, incentives to avoid providing care for patients who are difficult to treat or patients . . .