Such surveys might be appropriate for measuring certain outcomes, including subjective func- tional status, symptoms, knowledge, and overall satisfaction with the care process. However, critics point out that such measures can be disproportionately weighted by items un- related to care, including availability of channels on the hospital television, food menu choices, and parking con- venience. In addition, standardized tools for symptom measurement and for patient subsets are generally lacking. For example, the response to the question, Did this pro- cedure save your life? could be different for a patient un- dergoing PCI with an acute myocardial infarction and a patient with stable angina. In addition, validated risk- adjustment models for patient survey data do not currently exist. Although the writing committee believes that patient surveys are an important area for future development (see also Section 4.1.2: Patient Education/ Shared Decision Making Measures), these limitations raised concerns about their inclusion in the present document. 4.3. Structural Measures For PCI, measures to evaluate process and outcomes are more clearly substantiated by an evidence base than are structural measures. Still, compared with many clinically important process and outcome measures, it is easier to assess structural measures and, importantly, to track changes longitudinally without need for risk adjustment. Given these considerations, as well as interest in and evi- dence on registries and the role of case volume in out- comes, we elected to include 3 measures of structure: measure 9 (regional or national PCI registry participation), measure 10 (annual operator PCI volume) (quality improvement only), and measure 11 (annual hospital PCI volume). It is the consensus of the writing committee that these structural measures can provide important contribu- tions to the assessment of care equity and safety without imposing undue data collection burden on hospitals or practitioners. 