Payments systems linked to performance need to have accurate quality metrics that encourage physicians to offer services to all patients, including those whose health is complicated by multiple conditions. In many cases the physician performance metrics do not include adequate adjustment for patients with multiple chronic conditions. Most existing quality metrics have the tendency to encourage clinicians to avoid medically complex patients. More refined performance measures would account for patients with multiple chronic conditions and thereby strengthen the capacity of performance-based payment systems to support care for those with multiple conditions.