other individual and community conditions, but the exact contribution of each factor is unknown and may vary over place and time.
A life-course perspective adds additional complexity to the analysis because differences in health outcomes may relate not only to contemporaneous characteristics of health systems, but also to those that existed years earlier when current conditions or diseases were developing. This scenario is especially true for chronic diseases like diabetes and heart failure, which claim lives decades after problems with cardiovascular risk factors and glycemic control first appear. For such conditions, deficiencies in primary care in the 1970s and 1980s may explain current death rates better than the features of today’s health systems. The current health system matters more for care conditions that lead directly to health outcomes, such as birth outcomes and survival after a car crash or gunshot wound.
The research comparing health care systems cross-nationally is still evolving and cannot yet support any definitive conclusions about how the U.S. health system might contribute to or ameliorate the U.S. health disadvantage. Comparable international data for meaningful inferences require better data on both dependent (health outcomes) and independent variables (health systems). Although data from the OECD and WHO provide some comparative information on a handful of health system measures, these are much like the keys under the lamppost. A richer and more comprehensive set of data on a variety of carefully selected dimensions of morbidity and mortality and outcomes of care would be needed across countries to make valid comparisons.24
Few indicators for assessing the various dimensions of health care have been developed or undergone proper scientific validation. In particular, questions used on surveys such as those conducted by the Commonwealth Fund, which are widely cited in this chapter, have unknown correlations with health outcomes and may have variable meanings across countries. Limitations in statistical power and wide confidence intervals may limit the significance of rankings between one country and another or changes in ranking from year to year. Some questions used by the Commonwealth Fund change from year to year; these changes offer new insights on health systems, but they make it difficult to compare outcomes across time. The Commonwealth Fund gives equal weight to each measure; some weighting is probably warranted, but an empirical basis is lacking to know which characteristics patients value more highly or are more predictive of health outcomes.
Even the proper domains for assessing the performance of health systems
24Such data are lacking even within the United States. A recent Institute of Medicine (2011e) report indicated the lack of adequate data to evaluate the health of the American public or the performance of governmental public health agencies and recommended bold transformation of the nation’s health statistics enterprise.