Our greatest barriers were the lack of de nitive data on the risks and bene ts of ad hoc PCI and multivessel PCI and their role in shared decision making by patients and providers (49,50). The writing committee, therefore, decided that this topic might be considered in future updates of these measures or might be better handled by a writing com- mittee focused entirely on developing performance mea- sures for coronary revascularization (rather than just PCI). 6.2. Outcome Measures As noted previously, outcome measures are highly desirable but often dif cult to incorporate into performance measure sets because of vulnerability to in uences outside the pro- vider s control. Thus, outcome measures, particularly those intended for use in accountability, should be supported by strong data and should address risk-adjustment concerns. For example, the writing committee considered a measure of the incidence of dialysis after PCI. However, this was ultimately not included because the need for unexpected dialysis after PCI is extremely rare, and when dialysis does occur after PCI, it is often in patients with marginal renal function before the PCI for whom the possibility of dialysis was discussed previously. Creating a measure in this area might dissuade these patients, who are often at high risk for coronary artery disease, from undergoing PCI. Several members of the writing committee supported the inclusion of a related measure of acute kidney injury after PCI that would depend on laboratory assessments of renal function. However, controversy exists about the diagnosis of acute kidney injury in this setting, and in many patients, it would require multiple blood tests that are otherwise not indicated. Similarly, the writing committee considered a measure assessing rates of blood transfusion after PCI. 