摘要：Objectives. We compared the extent of socioeconomic differences in use of health care services based on wealth (i.e., accumulated assets) as the socioeconomic ranking variable with the extent of differences based on income to explore the sensitivity of the estimates of equity to the choice of the socioeconomic indicator. Methods. We used data from the Health and Retirement Study in the United States and the Survey of Health, Ageing, and Retirement in Europe to estimate levels of income- and wealth-related disparity in use of physician and dental services among adults 50 or older in 12 countries. Results. We found socioeconomic differences in use of physician services after standardizing for need in about half of the countries studied. No consistent pattern in levels of disparity measured by wealth versus those measured by income was found. However, the rich were significantly more likely to use dental services in all countries. Wealth-related differences in dental service use were consistently higher than were income-related differences. Conclusions. We found some support for wealth as a more sensitive indicator of socioeconomic status among older adults than was income. Wealth may thus allow more accurate measurements of socioeconomic differences in use of health care services for this population. Governments try to protect the population from the financial consequences of ill health by providing health care services on the basis of need and not ability to pay. In Europe, such policies have been implemented at both the national and supranational levels 1 ; in the United States, publicly funded programs such as Medicare, Medicaid, and the State Children's Health Insurance Program strive for similar ends. Distributing health care resources according to need may improve population health and may even reduce the health inequalities that are widespread in high-income countries. 2 Analyses based on the concept of the concentration curve, which compares the cumulative distribution of use of health care services with the cumulative distribution of income in a population, consistently reveal, after control for need, that use of health care services is greater among higher-income groups (i.e., a distribution that is more concentrated among the rich) in member countries of the Organisation for Economic Co-Operation and Development (OECD). 3 , 4 Although evidence for income-related differences in use of general practitioner or inpatient services is weaker, evidence exists for significant differences, by income, in the probability and number of specialist physician and dentist visits in almost all OECD countries. 3 , 4 Studies that focused on older populations also revealed evidence of differences in use of health care services by income 5 – 9 and education. 10 In the United States, income-related differences in use of health care services appear to be greatest among those 65 years and older. 11 Research on health inequalities in later life is complicated by “survival selection” caused by structural inequalities in society. 12 Some population subgroups (e.g., manual workers) have higher-than-average mortality and morbidity rates; in such groups, late-life survivors, by being healthier than those who have died, are not representative of the group. Therefore, researchers expect health inequalities across socioeconomic groups to narrow with age. Another complicating factor is the difficulty of measuring socioeconomic status (SES) in later life. 12 Among people who are retired, income and occupation status lose their significance, and wealth (i.e., accumulated economic assets) becomes more important. 13 – 17 One indicator of wealth, home ownership without debt, is important to consider in this connection because it effectively substitutes income that would otherwise be spent on rent or mortgage payments for income that is spent on health care. 18 The level of highest educational attainment is also an important indicator of SES. 15 There is likely a dynamic relationship between education and wealth, such that those who are better educated will also be able to accumulate more wealth by having higher levels of income, savings, and investment. One would therefore expect SES to be incorrectly measured if wealth is not considered. 18 Indeed, a study measuring the effects of housing assets on health status among those 55 years and older in Spain found that assets (but not income) were significantly and positively associated with better self-reported health and that inequalities in health were almost completely explained by differences in housing wealth. 19 Because population rankings based on income differ from those based on wealth, analyses of socioeconomic health inequalities and socioeconomic differences in use of health care services will yield different results depending on which indicator is chosen as the ranking indicator for SES. Among the retired population, levels of income are likely to vary much less than levels of wealth, as is shown in the descriptive analysis of the Health and Retirement Study (HRS). 20 In addition, when comparing retired and employed groups, income is less comparable than broader measures of wealth. But there has been no attempt yet to systematically investigate differences in use of health care services using wealth as the ranking variable instead of income. In our study, we addressed the following question: Are socioeconomic differences in use of health care services greater when they are measured by wealth than by income? We hypothesized that wealth would be a more sensitive indicator of socioeconomic status than would income in a population in which many people are retired. Therefore, differences in use by wealth were expected to be greater than were differences by income.
