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 bene t in asymptomatic patients to be uncertain in pa- tients with 2- or 3-vessel [coronary artery disease] (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 insuf cient data. However, the AUC, as rated by experts, vary in their assessments of the usefulness of PCI in this setting from uncertain to appropriate, on the basis of the additional factors described previously (e.g., 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 the AUC as tools. Finally, the writing committee considered that, at the present time, the current measure does not entirely meet the strict criteria for accountability measures as put forth by Chassin et al. (27) and the ACC/AHA Task Force on Performance Measures (28). For example, the measure- ment 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 (i.e., treating the right patient). Without existing data on its use in test populations, however, it is dif cult to JACC Vol. 63, No. 7, 2014 Nallamothu et al. 