sures like procedure volume are considerably more predictive of subsequent hospital performance than any known processes of care or direct mortality measure (Figure F-1).

A second advantage is efficiency. A single structural measure may be associated with numerous outcomes. For example, with some types of cancer surgery, hospital or surgeon procedure volume is associated not only with lower operative mortality, but also with lower perioperative morbidity and higher late survival rates (Bach et al., 2001; Begg et al., 2002; Finlayson and Birkmeyer, 2003). Intensivist model ICUs are linked to shorter length of stay and reduced resource use, as well as lower mortality (Pronovost et al., 2002, 2004).

The third and perhaps most important advantage of structural variables is expediency. Many can be assessed easily with readily available administrative data. Although some structural measures require surveying hospitals or providers, such data are much less expensive to collect than measures requiring patient-level information.

Limitations

Among the downsides, there are relatively few structural measures that may be potentially useful as quality indicators. Their use in ambulatory care is particularly limited. Second, in contrast to process measures, most structural measures are not readily actionable. For example, a small hospital cannot readily make itself a high volume center, but it can increase how many of its surgical patients receive antibiotic prophylaxis. Thus, while selected structural measures may be useful for selective referral initiatives, they have limited value for quality improvement purposes.

Finally, structural measures generally describe groups of hospitals or providers with better performance, but they do not adequately discriminate performance among individuals. For example, in aggregate, high-volume hospitals have much lower mortality rates than lower volume centers for pancreatic resection. However, some individual high-volume hospitals may have high mortality rates, while some low-volume centers may have excellent performance (Shahian and Normand, 2003). In this way, structural measures are viewed as “unfair” by many providers.

PROCESS OF CARE MEASURES

Processes of care are the clinical interventions and services provided to patients. Although only occasionally applied as performance measures for surgery (e.g., appropriate use of perioperative antibiotics), process measures are the predominant quality indicators for both inpatient and outpatient medical care (Table F-2). In the latter setting, process measures



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