Thus, subtle differences between the AUC and guidelines do exist, particularly for PCI. For example, the guidelines for PCI categorize the usefulness of these procedures for survival benefit in asymptomatic patients to be uncertain in patients with 2- or 3-vessel [coronary artery dis- ease] (with or without involvement of the proximal [left anterior descending] artery) or 1-vessel proximal [left anterior descending] disease (Class IIb recommendation), on the basis of insufficient data. However, the AUC, as rated by experts, vary in their assess- ments of the usefulness of PCI in this setting from uncertain to appropriate, on the basis of the additional factors described previ- ously (eg, current medical therapy, noninvasive studies). Second, the criteria for the AUC are becoming a frequent part of daily clinical practice and of quality-improvement efforts, but they are not entirely noncontroversial.26 We therefore created a measure that more broadly captured appropriate use of PCI, using both the guidelines and theAUC as tools. Finally, the writing committee considered that, at the pres- ent time, the current measure does not entirely meet the strict criteria for accountability measures as put forth by Chassin and the ACC/AHA Task Force on Performance For example, the measurement of appropriateness of PCI is certainly consistent with 2 criteria, in that it is based on a strong foundation of research and captures a process proximate to a desired outcome (ie, treating the right patient). Without existing data on its use in test populations, however, it is difficult to know whether the current measure accurately cap- tures appropriateness (as opposed to encouraging gaming) or whether it will lead to unintended consequences by discourag- ing operators from taking on difficult or high-risk procedures where, although the risk is high, the benefit could be great (ie, whether the measure will promote underuse). 