[Obesity Discussion]

Table 5 presents the adjusted proportions of uninsured and insured adults receiving recommended services for diabetes management. Increased income did not attenuate the association between being uninsured and using fewer services for diabetes, although increased income trended toward significantly increasing the likelihood of uninsured compared with insured diabetics receiving foot examinations (P for interaction = .06). We found that increased income did not significantly increase the likelihood of uninsured compared with insured diabetics receiving cholesterol and glycosylated hemoglobin measurements and foot examinations (P values >.05), while increased income significantly decreased the likelihood of uninsured compared with insured diabetics receiving eye examinations and both influenza and pneumococcal vaccinations (P values for each interaction <.02). In addition, when comparing income levels rather than examining the trend across income, we found that increased income did not significantly attenuate the association between being uninsured and using fewer diabetes services for nearly every successive income category (P values >.05).


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Table 5. Adjusted Proportion of Uninsured and Insured Adults Receiving Services for Diabetes Management*

Our study provides recent, nationally representative estimates of the use of recommended services for cancer prevention, cardiovascular risk reduction, and diabetes management for insured and uninsured adults with varying annual household incomes. We found that high numbers of uninsured and lower-income adults are not receiving recommended care—challenging the views of a majority of people in the United States who believe that the uninsured are able to get the care they need from physicians and hospitals.32 For instance, while the insured population met or exceeded the Healthy People 2010 target goals of 90% for cervical cancer screening, 70% for breast cancer screening, and 50% for colorectal cancer screening,33 our study found the uninsured fell well short of these goals, reporting 77%, 52%, and 29% use, respectively.

In addition, our findings indicate that even among higher-income adults, lacking insurance was associated with significantly decreased use of recommended health care services; we found that increased income did not attenuate the association between being uninsured and using fewer recommended health care services for cancer prevention, cardiovascular risk reduction, and diabetes management. The gap in the use of recommended care between uninsured and insured adults did not narrow significantly as income increased for any recommended service we examined. In fact, we found that the gap in the use of recommended care between uninsured and insured adults significantly widened as income increased for use of cervical and breast cancer screening, serum cholesterol screening, and eye examination and influenza and pneumococcal vaccination for diabetes management. In these cases, income not only failed to attenuate the association between being uninsured and using fewer recommended health care services, but the effect of lacking insurance was more pronounced for the higher-income uninsured than the lower-income uninsured. Moreover, when using the comparison between successive income levels rather than the trend across income, we found that for nearly every comparison, increased income did not significantly attenuate the association between being uninsured and using fewer recommended health care services. Thus, our findings are not limited to inferences regarding the highest-income uninsured, but are relevant for uninsured adults of all incomes.

There are several possible explanations for our findings. Our research may indicate that a greater proportion of uninsured than insured adults believe that the recommended health care services are not sufficiently beneficial either to purchase using out-of-pocket funds or to receive by enrolling in health insurance. In fact, those who do not believe care is sufficiently beneficial may also be more likely to forego purchasing insurance. These individuals may believe that preventive and chronic care does not sufficiently reduce the risk of disease or death to warrant its cost and thereby reduce use of these services. In addition, adults for whom such services are recommended by national guidelines may not believe that they need these services because they do not know that they meet the recommended eligibility criteria. Also, prior research has suggested that individuals may not purchase health insurance when faced with declining real incomes.34 After not purchasing health insurance, these fiscal pressures may also lead higher-income uninsured adults to use fewer health care services, especially preventive and chronic care. Lastly, we may not have observed a narrowing of the gap between the use of recommended care of uninsured and insured adults as income increases because the effect of lacking insurance may be reduced for the lower-income uninsured by the availability of the existing safety net of hospitals, clinics, and physicians.

If a greater proportion of uninsured adults do not believe that these recommended services are of sufficient value to purchase using out-of-pocket funds, there are 2 important policy implications to consider. First, policy makers attempting to improve health and health care for the uninsured should recognize that targeting only the lower-income uninsured may miss some individuals experiencing the consequences of lacking health insurance. Both lower-income and higher-income uninsured adults fail to receive important recommended services for cancer prevention, cardiovascular risk reduction, and diabetes management. Second, if adults do not understand that these recommended health care services are of sufficient value, policy makers and physicians may need to improve educational strategies. Use of preventive or chronic care services involves benefits and costs to both individuals and society. Societal benefits or benefits not realized by the individual may include prevention of the spread of contagious diseases or reduction in future health care costs. Future health care costs are likely to be borne by the federal government since most US residents are insured by Medicare at age 65 years. However, an individual's perceived net benefit of a service may include costs beyond explicit health care costs (ie, time to obtain service); these costs may vary with income. That these costs may be greater for higher-income individuals may explain why the higher-income uninsured may not choose to obtain services. It is important to note that it is possible that in situations in which the net benefit to the individual is low, the net benefit to society may still be high. Thus, society may have an interest in improving individuals' understanding of the benefits of recommended preventive and chronic care if this could increase use of recommended care services.

Limitations

There are several limitations to consider when evaluating our study. First, our study is based on self-reported data from a large, nationally representative survey examining health risks and behaviors. Some questions that could have improved our study were not asked, such as type of health insurance coverage or out-of-pocket health care costs. In addition, although the tendency of respondents to overreport health promotion and disease-prevention activities is widely recognized,35-37 there is little reason to think that overreporting would be more prevalent among lower-income adults compared with higher-income adults, or among uninsured compared with insured adults, and hence should not bias our results substantially. Second, information on income was either not known or not reported for 15% of our weighted sample of adults, a rate consistent with other survey years.38 Because prior research has shown that differences in income nonreporting are small across levels of employment status, occupation, and education,39 we believe that income nonresponse is unlikely to systematically affect estimates of the relationship between income, insurance, and health care use. Third, previous research has shown that relying on a single point-in-time question regarding health insurance coverage may lead to an underestimate of the population at risk from being uninsured.40 In subgroup analyses among adults for whom time without health insurance was collected, we found that higher-income adults were more likely to be uninsured for shorter periods of time when compared with lower-income adults. However, we could find no systematic association between higher income and use of recommended health care services when comparing adults without health insurance for less than 5 years with adults without health insurance for 5 years or more. Finally, cross-sectional data can demonstrate associations but cannot prove causality. The higher-income uninsured in our study may differ in unobservable ways from the higher-income insured in their propensity to use health care services. Therefore, these results do not necessarily indicate that all high-income individuals would use health care services at the rates reported, should they become uninsured.

The number of uninsured Americans increased by more than 6 million adults between 2000 and 2004, primarily because of a decline in employer-sponsored coverage without a compensatory increase in federal- and state-sponsored coverage.1 According to our study, many uninsured adults continue not to receive recommended health care services. Currently, many of the proposed health care reforms from both the public and private sector involve increased out-of-pocket cost-sharing or deductibles, such as the recent authorization of health savings accounts through the 2003 Medicare Modernization Act.13 The results of our study suggest that such reforms may increase the number of adults not receiving recommended health care; adults using out-of-pocket funds to purchase health care services, whether they are enrolled in health savings accounts, employer-sponsored high-deductible insurance plans, or plans with substantial cost sharing, may not purchase recommended chronic and preventive care at levels comparable with adults enrolled in traditional health insurance plans. More research is needed to understand the use of preventive and chronic care services by individuals using out-of-pocket funds to purchase care, but perhaps recommended preventive and chronic care should be excluded from large co-payments or deductibles. Substantial action is necessary to increase the use of recommended care in the United States and these policies should address the needs of both lower-income and higher-income uninsured adults.