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3 Effects of Health Insurance on Health This chapter presents the Committee's review of studies that address the impact of health insurance on various health-related outcomes. It examines re- search on the relationship between health insurance (or lack of insurance), use of medical care and health outcomes for specific conditions and types of services, and with overall health status and mortality. There is a consistent, positive relationship between health insurance coverage and health-related outcomes across a body of studies that use a variety of data sources and different analytic approaches. The best evidence suggests that health insurance is associated with more appropriate use of health care services and better health outcomes for adults. The discussion of the research in this chapter is organized within sections that encompass virtually all of the research literature on health outcomes and insurance status that the Committee identified. The chapter sections include the following: · Primary prevention ~nr] Train Tic · Cancer care and outcomes disease) .~, ~ · Chronic disease management, with specific discussions of diabetes, hyper- tension, end-stage renal disease (ESRD), HIV disease, and mental illness · Hospital-based care (emergency services, traumatic injury, cardiovascular · Overall mortality and general measures of health status The Committee consolidated study results within categories that reflect both diseases and services because these frameworks helped in summarizing the indi- vidual studies and subsumed similar research structures and outcome measures. Older studies and those of lesser relevance or quality are not discussed within this 47
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48 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE chapter devoted to presenting study results and reaching Committee findings. However, all of the studies reviewed are described briefly in Appendix B. The studies presented in some detail in this chapter are those that the Com- mittee judged to be both methodologically sound and the most informative re- garding health insurance effects on health-related outcomes.) Most studies report a positive relationship between health insurance coverage and measured out- comes. However, all studies with negative results that are contrary to the Committee's findings are presented and discussed in this chapter. Appendix B includes summaries of the complete set of studies that the Committee reviewed. In the pages that follow, the Committee's findings introduce each of the five major sections listed above and also some of the subsections under chronic disease and hospital-based care. All of the Committee's specific findings are also presented together in Box 3.12 in the concluding section of this chapter. These findings are the basis for the Committee's overall conclusions in Chapter 4. PRIMARY PREVENTION AND SCREENING SERVICES Finding: Uninsured adults are less likely than adults with any kind of health coverage to receive preventive and screening services and less likely to receive these services on a timely basis. Health insurance that provides more extensive coverage of preventive and screening services is likely to result in greater and more appropriate use of these services. Finding: Health insurance may reduce racial and ethnic disparities in the receipt of preventive and screening services. These findings have important implications for health outcomes, as can be seen in the later sections on cancer and chronic diseases. For prevention and screening services, health insurance facilitates both the receipt of services and a continuing care relationship or regular source of care, which also increases the likelihood of receiving appropriate care. Insurance benefits are less likely to include preventive and screening services (Box 3.2) than they are physician visits for acute care or diagnostic tests for symptomatic conditions. However, over time, coverage of preventive and screen- iChapter 2 discusses the features of observational (nonexperimental) studies that are necessary for methodological soundness. All quantified study results that are presented in this chapter and in Chap- ter 4 are significant at least at the 95 percent confidence interval. If results do not meet this level of statistical significance, the confidence interval is reported. See "confidence interval" in Appendix C for further discussion.
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EFFECTS OF HEALTH INSURANCE ON HEALTH 49 ing services has been increasing. In 1998, about three-quarters of adults with employment-based health insurance had a benefit package that included adult physical examinations; two years later in 2000, the proportion had risen to 90 percent (KPMG, 1998; Kaiser Family Foundation/HRET, 2000~. Yet even if health insurance benefit packages do not cover preventive or screening services, those with health insurance are more likely to receive these recommended services because they are more likely to have a regular source of care, and having a regular source of care is independently associated with receiving recommended services (Bush and Langer, 1998; Gordon et al., 1998; Mandelblatt et al., 1999; Zambrana et al., 1999; Cummings et al., 2000; Hsia et al., 2000; Breen et al., 2001~. The effect of having health insurance is more evident for relatively costly services, such as mammograms, than for less costly services, such as a clinical breast exam (CBE) or Pap test (Zambrana et al., 1999; Cummings et al., 2000; O'Malley et al., 2001~.
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50 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE According to several large population surveys conducted within the past decade, adults without health insurance are less likely to receive recommended preventive and screening services and are less likely to receive them at the fre- quencies recommended by the United States Preventive Services Task Force than are insured adults.2 The 1992 National Health Interview Survey (NHIS) docu- mented receipt of mammography, CBE, Pap test, fecal occult blood test (FOBT), sigmoidoscopy, and digital rectal exam by adults under 65 (Potosky et al., 1998~. Those with no health insurance had significantly lower screening rates compared to those with private coverage and compared to those with Medicaid for every service except sigmoidoscopy. The odds ratios (ORB) for receiving a screening service if uninsured compared with having private health insurance ranged from 0.27 for mammography to 0.43 for Pap test.3 The 1998 NHIS found that, although rates of screening at appropriate inter- vals had increased generally over the preceding decade, they remained substan- tially lower for uninsured adults than for those with any kind of health insurance (Breen et al., 2001~.4 In a multivariable analysis that adjusted for age, race, educa- tion, and a regular source of care, uninsured adults were significantly less likely than those with any kind of coverage to receive a Pap test, mammography, and colorectal screening (FOBT or sigmoidoscopy) (ORs ranged from 0.37 to 0.5) (Breen et al., 2001~. The study reported a strong relationship between having a regular source of care and timely receipt of these screening services in addition to the relationship between health insurance and screening. Studies using other national samples report results consistent with those of the NHIS. A study of more than 31,000 women between ages 50 and 64 who responded to telephone surveys conducted between 1994 and 1997 about their receipt of mammograms, Pap smears, and colorectal cancer screening (either FOBT or sigmoidoscopy) found that uninsured women were significantly less likely to 2Earlier studies based on the 1986 Access to Care Survey and the 1982 NHIS had findings consis- tent with those of the more recent nationally representative sample surveys regarding receipt of preventive and screening services by those without health insurance (Hayward et al., 1988; Woolhandler and Himmelstein, 1988). 3Enrollees in private managed care plans is the reference group; however, fee-for-service enrollees did not have significantly different screening rates from those of managed care enrollees. The odds ratio is the relative odds of having an outcome in the uninsured and insured groups. For example, if the odds of receiving a Pap test are 2:1 in a group of uninsured women (i.e., two of every three women or 67 percent receive the test) and the odds are 4:1 in a group of women with insurance (i.e., four of every five women, or 80 percent, receive the test), the odds ratio of uninsured compared to insured women is 0.5 (2:1/4:1). The OR is not a good estimate of the relative risk (the probability of been screened in the uninsured group divided by the probability of being screened in the insured group) because screening is not a rare event. Throughout this report the results of particular studies, if reported as odds ratios or as relative risks, will be presented as the ratio of the uninsured to the insured rates (in this example, as an OR of 0.5). 4Comparing results presented in Potosky et al., 1998, and Breen et al., 2001, the gap in screening rates between insured and uninsured adults decreased between 1992 and 1998.
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EFFECTS OF HEALTH INSURANCE ON HEALTH 5 have received these tests than were women with private prepaid plan insurance (ORs ranging from 0.30 to 0.50) (Hsia et al., 2000~. This study also found a strong relationship between having a regular source of care and receipt of screening services. Health insurance was an independently significant predictor. Another study based on several years of the Behavioral Risk Factor Surveillance System (BRFSS) for older adults (55 through 64) found that uninsured men and women were much less likely than their insured counterparts to receive cancer or heart disease screening tests and also much less likely to have a regular source of care (Powell-Griper et al., 1999; see Table 4.1~. Disparities Among Population Groups A review of the literature on the interaction of race, ethnicity, and socioeco- nomic status (SES) with health insurance, concluded that health insurance makes a positive contribution to the likelihood of receiving appropriate screening ser- vices, although racial and ethnic disparities persist independent of health insurance (Haas and Adler, 2001~. Studies of the use of preventive services by particular ethnic groups, such as Hispanics and African Americans, find that health insurance is associated with increased receipt of preventive services and increased likelihood of having a regular source of care, which improves one's chances of receiving appropriate preventive services (Solis et al., 1990; Mandelblatt et al., 1999; Zambrana et al., 1999; Wagner and Guendelman, 2000; Breen et al., 2001; O'Malley et al., 2001~. Breen and colleagues (2001) modeled the expected increase in screening rates for different ethnic groups if they were to gain health insurance coverage and a regular source of care. This "what-if'' model suggests that those groups for whom screening rates are particularly low (e.g., receipt of mammography by Hispanic women, colorectal screening of African-American men) would make the largest gains (an 11 percentage-point increase in mammography rates for Hispanic women To 77 percent] and a 5 percentage-point increase in colorectal screening for African-American men To 31 percent] (Breen et al., 2001~. Extensiveness of Insurance Benefits The type of health insurance and the continuity of coverage have also been found to affect receipt of appropriate preventive and screening services. Faulkner and Schauffler (1997) examined receipt of physical examinations, blood pressure screening, lipid screening for detection of cardiovascular disease, Pap test, CBE, and mammography and identified a positive and statistically significant "dose- response" relationship between the extent of coverage for preventive services (e.g., whether all such services, most, some, or none were covered by health insurance). Insurance coverage for preventive care increased men's receipt of preventive services more than it did that of women. Men with no coverage for preventive services were much less likely than men with complete coverage for
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52 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE such services to receive them (ORs for receipt of specific services ranged from 0.36 to 0.56~. Women with no preventive services coverage also received fewer of these services than did women with full coverage for them (ORs for specific services ranged from 0.5 to 0.83) (Faulkner and Schauffler, 1997~. Ayanian and colleagues (2000) used the 1998 BRFSS data set to analyze the effect of length of time without coverage on receipt of preventive and screening services for adults between ages 18 and 65. Those without coverage for a year or longer were more likely than those uninsured for less than one year to go without appropriate preventive and screening services. For every generally recommended service (mammography, CBE, Pap smear, FOBT, sigmoidoscopy, hypertension screening, and cholesterol screening), the longer-term uninsured were signifi- cantly less likely than persons with any form of health insurance to receive these services (Ayanian et al., 2000~. Negative Findings In the Committee's review, the one study that did not find a positive effect of insurance coverage compared mammography use among clients of various sites of care in Detroit, Michigan: two health department clinics, a health maintenance organization (HMO), and a private hospital (Burack et al., 1993~. This study found no significant differences among women according to their health insurance status but did find that patients with more visits annually for any service (seven or more) were more likely to receive mammography. All women in this study had access to a primary care provider and, in the case of uninsured women, to clinics with the mission of serving the uninsured. These factors may explain why unin- sured women had mammography rates as high as those of women with insurance. CANCER CARE AND OUTCOMES Finding: Uninsured cancer patients generally have poorer outcomes and are more likely to die prematurely than persons with insurance, largely because of delayed diagnosis. This finding is supported by population-based studies of breast, cervical, colorectal, and prostate cancer and melanoma. The studies analyzing health-related outcomes for cancer patients provide some of the most compelling evidence for the effect of health insurance status on health outcomes (Box 3.3~. This evidence comes from research based on area or statewide cancer registries, which provide large numbers of observations and reflect almost all cases occurring in a geographic region. Multivariable data analysis is used to determine the independent effects of health insurance, by controlling for demographic, SES, and clinical differences among study subjects. In addition to receiving fewer cancer screening services, uninsured adults are at greater risk of late-stage, often fatal cancer. Early diagnosis frequently improves
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EFFECTS OF HEALTH INSURANCE ON HEALTH 53 the chances of surviving cancer. Generally, in studies examining the stage at which cancer is diagnosed, those with private health insurance have the best outcomes and those with no insurance have the worst (i.e., the highest proportion of late- stage diagnoses), with intermediate outcomes for Medicaid enrollees. In some studies however, the outcomes for Medicaid enrollees are comparable to those for uninsured cancer patients (Roetzbeim et al., 1999~. Both because of an assump- tion of similarity in SES between uninsured and Medicaid patients and because of small numbers of observations in the separate categories, some studies report combined results for Medicaid and uninsured patients and compare these findings with those for privately insured patients (e.g., Lee-Feldstein et al., 2000~. In studies assessing the outcomes for adults with cancer stage of disease at diagnosis and mortality Medicaid enrollees often do no better, and sometimes do worse, than uninsured patients. This similarity in experience between patients enrolled in Medicaid and those without any coverage may reflect the fact that uninsured persons in poor health, once they seek care, may become enrolled in
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54 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE Medicaid as a result of their frequent interactions with the health care system (Davidoffet al., 2001; see Box 2.1~. Also, Medicaid enrollees tend to have discon- tinuous coverage and thus may have had less regular access to screening services. Consequently, persons with Medicaid at the time of a cancer diagnosis may have been without coverage for some prior period (Carrasquillo et al., 1998; IOM, 2001a; Perkins et al., 2001~. For example, one study of women under 65 with Medi-Cal coverage (California's Medicaid and indigent care program) who were diagnosed with breast cancer found that, among those who had been uninsured during the year prior to their diagnosis (18 percent of all Medi-Cal enrollees), late- stage diagnosis was much more likely than among those who had been continu- ously enrolled for the previous 12 months (ORs of 3.9 for those who had been uninsured and 1.4 for those continuously covered by Medi-Cal, compared with all other women ages 30-64 diagnosed with breast cancer) (Perkins et al., 2001~. With this general background on the nature of the research examining health insurance status effects, the remainder of this section discusses study results for five specific cancers. Breast Cancer Uninsured women and women with Medicaid are more likely to receive a breast cancer diagnosis at a late stage of disease (regional or distant) and have a 30- 50 percent greater risk of dying than women with private coverage, as shown in studies based on three different state or regional cancer registries (Ayanian et al., 1993; Roetzbeim et al., 1999, 2000; Lee-Feldstein et al., 2000~. In a study using the New Jersey Cancer Registry, Ayanian and colleagues (1993) identified 4,675 women 35 to 65 years of age diagnosed with breast cancer and assessed their stage of disease at diagnosis and their survival rates 4.5 to 7 years after diagnosis. The authors found that uninsured women were significantly more likely than privately insured women to be diagnosed with regional or late-stage cancer, as were patients with Medicaid. After controlling for stage of disease at diagnosis and other factors, uninsured women had an adjusted risk of death 49 percent higher than that of privately insured women, and women with Medicaid had a 40 percent higher risk of death than those who were privately insured. Using a regional cancer registry and Census data for 1987 through 1993, Lee- Feldstein and colleagues (2000) examined the stage of disease at diagnosis, treat- ment, and survival experience of about 1,800 northern California women under the age of 65 diagnosed with breast cancer. They found that women who were uninsured and publicly insured (primarily Medicaid), taken together, were twice as likely as privately insured women with indemnity coverage to be diagnosed at a late stage of disease. Over a four- to ten-year follow-up, uninsured and publicly insured women had higher risks of death from both breast cancer (42 percent higher) and all causes (46 percent higher) than did privately insured women with indemnity coverage. The likelihood of receiving breast-conserving surgery did not differ between these two groups.
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EFFECTS OF HEALTH INSURANCE ON HEALTH 55 In a review of approximately 9,800 Florida residents diagnosed with breast cancer in 1994, Roetzbeim and colleagues calculated that, after controlling for age, education, income, marital status, race, and comorbidity, women without insurance were more likely to be diagnosed with late-stage disease than women with private indemnity coverage (OR = 1.43) (Roetzbeim et al., 1999~. Women with Medicaid had an even greater likelihood of late-stage diagnosis compared with privately insured women (OR = 1.87~. In a subsequent analysis of mortality using the same registry data, the authors estimated that the relative risk (RR) of dying was 31 percent higher for uninsured women and 58 percent higher for women with Medicaid over a three to four-year follow-up period (Roetzbeim et al, 2000a). Further analysis suggested that stage of disease at diagnosis and, to a lesser extent, treatment modality appeared to account for the differences in sur- vival by insurance status. Finally, uninsured women were less likely than women with private coverage to receive breast-conserving surgery when stage at diagno- sis, comorbidities, and other personal characteristics were taken into account (OR = 0.70) (Roetzbeim et al., 2000a). Cervical Cancer Uninsured women are more likely to receive a late-stage diagnosis for inva- sive cervical cancer than are privately insured women. Ferrante and colleagues (2000) analyzed 852 cases of invasive cervical cancer reported in the Florida tumor registry for 1994 to determine factors associated with late-stage diagnosis. In bivariate analysis, being uninsured was associated with an increased likelihood of late-stage diagnosis (OR = 1.6~. In a multivariable analysis that adjusted for age, education, income, marital status, race, comorbidities, and smoking, uninsured women were more likely to present with a late-stage cancer compared to women with private indemnity coverage, although this finding was not statistically signifi- cant (OR = 1.49, confidence interval ACID: 0.88-2.50~. The outcome for Medic- aid enrollees was similar to that of privately insured women in both bivariate and multivariable analysis (Ferrante et al., 2000~. Colorectal Cancer Uninsured patients with colorectal cancer have a greater risk of dying than do patients with private indemnity insurance, even after adjusting for differences in the stage at which the cancer is diagnosed and the treatment modality. Using the Florida cancer registry for 1994, Roetzbeim and colleagues (1999) analyzed the relative likelihood of late-stage diagnosis by insurance status for more than 8,000 cases of colorectal cancer. In a multivariable analysis adjusting for sociodemo- graphic characteristics, smoking status, and comorbidities, uninsured patients were more likely to be diagnosed with late-stage colorectal cancer than were patients with private indemnity coverage (OR = 1.67~. Medicaid enrollees had a statisti-
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56 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE c ally insignificant greater likelihood of late-stage disease compared to patients with indemnity coverage (OR = 1.44, CI: 0.92-2.25~. A subsequent analysis of largely the same data set (9,500 cases) that adjusted for sociodemographic factors and comorbidities but not for smoking estimated the adjusted mortality risk for uninsured patients with colorectal cancer to be 64 percent greater over a three- to four-year follow-up period than that for patients covered by private indemnity plans (Roetzbeim et al., 2000b).5 Even after adjust- ing for stage of disease at diagnosis, the risk of death for uninsured patients was 50 percent higher than that for the privately insured, and after further adjustment for treatment modality, the risk for uninsured patients was 40 percent higher (Roetzbeim et al., 2000b). Prostate Cancer In addition to delayed diagnosis and greater risk of death, uninsured prostate cancer patients have been found to experience a decrease in health-related quality of life after their diagnosis and during treatment, unlike publicly and privately insured patients. A study of about 8,700 cases of newly diagnosed prostate cancer reported to the Florida cancer registry in 1994 found that uninsured men were more likely to be diagnosed at a late stage of the disease than were men with private indemnity insurance (OR = 1.47) (Roetzbeim et al., 1999~. A study of 860 men in 26 medical practices with newly diagnosed prostate cancer evaluated their health-related quality of life (HRQOL) at three- to six-month intervals over a two-year period (Person et al., 2001~. Although uninsured men diagnosed with prostate cancer did not have a lower HRQOL at diagnosis, their HRQOL de- creased over the course of their disease and treatment, in contrast to that of HMO and Medicare patients. The authors suggest that "patients undergoing aggressive treatment, which can itself have deleterious effects on quality of life, are exposed to further hardships when they do not have comprehensive health insurance upon which to support their care" (Person et al., 2001, p. 357~. Melanoma Uninsured patients, as well as Medicaid patients have been found to be more likely to be diagnosed with late-stage melanoma than are privately insured pa- tients. Among 1,500 patients diagnosed with melanoma, uninsured patients were more likely to have late-stage (regional or distant) disease than those with private indemnity coverage (OR = 2.6) (Roetzbeim et al., 1999~. The small number of Medicaid patients with melanoma (13) included in this study also had a much greater chance of being diagnosed with late-stage cancer. 5Smoking has been associated with an increased risk of colorectal cancer (Chao et aL,2000).
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EFFECTS OF HEALTH INSURANCE ON HEALTH 79 applied appropriateness criteria to identify cases in which the use of these proce- dures was considered nondiscretionary or necessary. In the studies that examined overall utilization rates, the differences found by insurance status could be attrib- uted to overutilization as well as underutilization. Angiography (cardiac catheterization) is an invasive diagnostic procedure that provides information to guide decisions about subsequent treatment options, in- cluding revascularization procedures. Sada and colleagues (1998) applied the crite- ria of the American College of Cardiology and American Heart Association Joint Task Force to a national data set of 17,600 myocardial infarction patients under 65 to identify nondiscretionary angiography for revascularization candidates consid- ered to be at high risk. They estimated that in hospitals providing these cardiac procedures, patients with private FFS coverage who were deemed high-risk and for whom angiography was nondiscretionary were more likely than similarly high-risk uninsured patients or Medicaid patients to receive angiography. Among high-risk FFS patients, 84 percent received this service compared to 73 percent of high-risk uninsured patients and 60 percent of similar Medicaid patients (Sada et al., 1998~. Revascularization procedures (either CABG or PTCA) following a heart attack are also more likely to be performed on insured than uninsured patients. In two studies, uninsured patients were less likely to receive revascularization (either CABG or PTCA) than privately insured FFS patients (OR = 0.6 in the 1991 study and 0.8 in the 2000 study) (Young and Cohen, 1991; Canto et al., 2000~. Blustein and colleagues (1995) and Kuykendall and colleagues (1995) reported similar comparative findings regarding the revascularization of uninsured and privately insured patients (ORs in these studies ranged from 0.4 to 0.6~. InterHospital Transfers to Receive Services. For patients with AMI, health insurance facilitates access to hospitals that perform angiography and revascu- larization, whether admission is initial or by means of an interhospital transfer (Blustein et al., 1995; Canto et al., 1999; Leape et al., 1999~. In a study of California hospital admissions for AMI, Blustein and colleagues (1995) found that uninsured patients were less likely than privately insured patients to be admitted initially to a hospital that offered revascularization and much less likely to be transferred if admitted initially to one that did not (ORs = 0.71 and 0.42, respectively). Leape and colleagues (1999) reviewed 631 records for patients who had received angiography and subsequently met expert panel criteria for necessary revascularization. Overall, 74 percent of patients meeting these criteria received revascularization. Leape et al. found that in hospitals that also performed CABG and PTCA, there were no differences in rates of revascularization for patients with different insurance status. However, for patients initially hospitalized in facilities that did not perform CABG and PTCA, who required a transfer to another hospital to receive revascularization, the rates differed significantly by insurance
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80 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE status: 91 percent of Medicare patients, 82 percent of privately insured patients, 75 percent of Medicaid patients, and just 52 percent of uninsured patients received this indicated surgery (Leape et al., 1999~. Insurance Status and Racial and Gender Disparities. Health insurance has been shown to lessen disparities in the care for cardiovascular disease received by men compared to women and among members of racial and ethnic groups (Carlisle et al., 1997; Daumit et al., 1999, 2000~. An analysis of more than 100,000 hospital discharges with a principal diagno- sis of cardiovascular disease in Los Angeles County between 1986 and 1988 revealed significant differences in rates of angiography, CABG, and PTCA be- tween uninsured African-American and white patients but not between members of these ethnic groups who were privately insured (Carlisle et al., 1997~. In a multivariate analysis that controlled for demographic and clinical characteristics and hospital procedure volume, the odds ratios for uninsured African Americans to receive one of these services compared with uninsured whites ranged from 0.33 to 0.5 (Carlisle et al., 1997~. A longitudinal study with a seven-year follow-up of a national random sample of patients who initially became eligible for the Medicare ESRD program in 1986 or 1987 found that once uninsured patients qualified for ESRD benefits, pro- nounced disparities by gender or race in their likelihood of receiving either angiography, CABG, or PTCA were eliminated (Daumit et al., 1999, 2000~. In the period prior to qualifying for Medicare, uninsured African Americans were far less likely than uninsured whites to undergo a cardiac procedure (OR = 0.07) (Daumit et al., 1999~. Uninsured women were also less likely than uninsured men to receive a cardiac procedure before qualifying for Medicare (OR = 0.4), and uninsured men were much less likely than men with private insurance to receive one (OR = 0.47) (Daumit et al., 2000~. In the case of both race and gender, differences in the receipt of these cardiac procedures were eliminated after gaining Medicare ESRD coverage. GENE12AL HEALTH OUTCOMES Finding: Longitudinal population-based studies of the mortality of uninsured and privately insured adults reveal a higher risk of dying for those who were uninsured at baseline than for those who initially had private coverage. Finding: Relatively short (one- to four-year) longitudinal studies document relatively greater decreases in general health status mea- sures for uninsured adults and for those who lost insurance coverage during the period studied than for those with continuous coverage.
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EFFECTS OF HEALTH INSURANCE ON HEALTH 8 This chapter concludes with a review of the studies evaluating the overall health status and mortality experience of insured and uninsured populations. As- sessments of general health outcomes such as self-reported health status and mor- tality or survival rates for uninsured adults under 65 compared to those with some form of health insurance (i.e., employment-sponsored, Medicaid, Medicare, indi- vidually purchased policies), present researchers with even greater challenges of analytic adjustment than those encountered in studies of specific health conditions. Not only might health insurance affect health status, but health status can affect health insurance status. Thus, it is difficult to interpret cross-sectional studies of health insurance and health status. However, several well-designed longitudinal studies with extensive analytic adjustments for covariates have found higher mor- tality and worse overall functional and health status among uninsured adults than among otherwise similar insured adults. Mortality Two studies provide evidence that uninsured adults are more likely to die prematurely than are their privately insured counterparts. Franks and colleagues (1993a) followed a national cohort of 4,700 adults age 25 or older for 13 to 17 years who, at the baseline interview, were either privately insured or uninsured. At the end of the follow-up period (1987), about twice as many participants who were uninsured at the time of the first interview had died as had those with private health insurance (18.4 percent compared with 9.6 percent). Controlling for sociodemographic characteristics, health examination findings, self-reported health status, and health behaviors, the risk of death for adults who initially were uninsured was 25 percent greater than for those who had private health insurance at the time of the initial interview (mortality hazard ratio = 1.25, CI: 1.00-1.55~. The magnitude ofthis independent health insurance effect on mortality risk was comparable to that of being unemployed, to lacking a high school diploma, or to being in the lowest income category (Franks et al., 1993a).l6 Because insurance status was measured only at the initial interview and thus did not reflect the subjects' cumulative insurance experience over the 13-17 year follow-up period, the difference found in mortality between uninsured and pri- vately insured persons most likely is an underestimate of differences in the mortal- ity experience of those who are continuously uninsured and those who are con- tinuously insured. A study by Sorlie and colleagues (1994) tracked the mortality experience of 148,000 adults between 25 and 65 years of age until 1987, a two- to five-year follow-up period. After adjusting for age and income, this study found that uninsured white men had a 20 percent higher risk of dying than white men with 16The lowest income category included those with a family income of less than $7,000 at the initial interview (1971-1975).
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82 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE employment-based health insurance. Uninsured black men and white women each had a 50 percent higher mortality risk than their counterparts with employ- ment-based coverage (Sorlie et al., 1994~. Among black women, insurance was not statistically associated with mortality. The authors also examined the mortality experience of insured and uninsured employed white men and women, adjusted for age and income. (Because of small sample size, they did not perform this analysis for black men and women.) Uninsured employed white men had a 30 percent greater risk of dying than their working counterparts with health insurance, and uninsured employed white women had a 20 percent greater risk over two to five years than their counterparts with health insurance (Sorlie et al., 1994~. Loss of Coverage and Changes in Health Status Over Time Persons who lose health insurance have been found to experience declines in their health status. Longitudinal studies that follow a cohort of individuals over time can provide a "before-and-after" picture of health status, comparing a group that maintained coverage with one that lost it. Such a design helps to minimize the possibility that unmeasured factors that vary along with health insurance status account for differences in health, a competing hypothesis that cannot be elimi- nated in cross-sectional studies. Lurie and colleagues (1984, 1986) took advantage of a natural experiment in the mid-1980s when California eliminated Medi-Cal coverage for a group of medically indigent adults. Following matched cohorts of adults seen at an internal medicine practice at a university clinic who either maintained or lost Medi-Cal coverage, the authors found that the patients who lost coverage reported signifi- cant decreases in perceived overall health at both six months and a year later, unlike those who maintained coverage. As discussed earlier in this chapter, partici- pants in this study with hypertension who lost coverage also experienced worsen- ing blood pressure control, while those who maintained coverage did not. Like those with chronic health conditions, adults in late middle age are particularly susceptible to deteriorations of function and health status if they lack or lose health insurance coverage. Baker and colleagues (2001) followed a group of more than 7,500 participants in the longitudinal Health and Retirement Survey (adults ages 51 to 61 at the outset) between 1992 and 1996. The authors compared three groups: 1. those who were continuously insured over the first two years (measured in 1992 and 1994~; 2. those who were continuously without insurance over that period; and 3. those who were intermittently uninsured, defined as those who lacked health insurance either in 1992 or in 1994, but not at both times (Baker et al., 2001~.
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EFFECTS OF HEALTH INSURANCE ON HEALTH 83 Ofthose who were continuously uninsured, 22 percent had a major declined in self-reported health, 16 percent of the intermittently uninsured experienced a major decline, and 8 percent of the continuously insured reported a major decline in health. In an analysis that controlled for sociodemographic characteristics, pre- existing medical conditions, and health behaviors, the authors estimated a 60 percent greater risk of a major decline in health for continuously uninsured persons and a 40 percent greater risk for intermittently insured persons, as com- pared with continuously insured persons. Continuously or intermittently unin- sured persons also had a 20 to 25 percent greater risk of developing a new difficulty in walking or climbing stairs than did those who were continuously insured (Baker et al., 2001~. Cross-Sectional Studies of Health Status Cross-sectional studies based on large national population surveys (Medical Expenditure Panel Survey MEWS, National Medical Expenditure Survey ENMESH, and Behavioral Risk Factor Surveillance System, provide snapshots of the subjective or self-reported health status of populations according to insurance status. These surveys report worse health status among those without insurance than among those with coverage. Two large studies with careful and extensive analytic adjustments for covarying personal characteristics are presented here. Franks and colleagues (1993b) examined the relationship between health insurance status and subjective health across several dimensions, including a gen- eral health perceptions scale, physical and role functions, and mental health, for 12,000 adults ages 25 through 64. The authors compared participants who had private health insurance for an entire year with those who had been without health insurance the entire year. In an analysis that controlled for age, sex, race, education, presence of a medical condition, and attitude toward medical care and insurance, uninsured adults had significantly lower subjective health scores across all dimensions. The effect on these measures of health of being uninsured was greater for lower-income persons than for those in families with incomes above 200 percent of the federal poverty level, although the effect persisted in both income groups. For both lower- and higher-income adults, the negative effect on perceived health of being uninsured was greater than that of having minority racial or ethnic status. Overall, the extent to which being uninsured negatively affected subjective health (a decrement of 4 points on a 100-point scale) was greater than that of having either of two diseases, cancer or gall bladder disease, and slightly lower than that for arteriosclerosis (Franks et al., 1993b). Ayanian and colleagues' (2000) analysis of the 1998 BRFSS compared self- i7A "major decline" in health was defined as a change from excellent, very good, or good health in 1992 to fair or poor health in 1996, or from fair health in 1992 to poor health in 1996 (Baker et al., 2001 ).
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84 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE TABLE 3.1 Unadjusted Self-Reported Health Status for 18-64 Year-Old Adults, BRFSS, 1998* (percent) Uninsured Uninsured Health Status 2 1 Year <1 Year Excellent 18 21 27 Very good 27 32 36 Good 35 33 26 Fair 16 11 ~ Poor 4 3 3 Insured All Year *Calculated Tom Table 1 in Ayan~an et al., 2000. SOURCE: Ayanian et al., 2000. reported health status among adults 18-64 who were uninsured for a year or longer, those uninsured for less than a year, and those with any kind of insurance, public or private. Table 3.1 presents the unadjusted results for the approximately 163,000 adults surveyed. One in five adults uninsured for a year or longer reported being in fair or poor health, compared with one in seven among those uninsured for less than a year, and one in nine for those with health insurance. The RAND Health Insurance Experiment In an experimental study conducted between 1975 and 1982, about 4,000 participants between 14 and 61 years were randomly assigned (in family units) to health insurance plans that differed in the amount of patient cost sharing required, ranging from free care to major deductible plans (95 percent cost sharing, with a maximum of $1,000 per family per year) (Brook et al., 1983; Newhouse et al., 1993~. Participants received a lump-sum payment at the beginning of the study to compensate them for their expected out-of-pocket costs if they were in cost- sharing plans. Participants were studied for a three- to five-year period. While persons in plans with any cost sharing had significantly fewer physician visits and hospitalizations than persons in a free-care plan, no difference was found overall between plans with any amount of cost sharing and those with no cost sharing. Free care did result in better outcomes for adults with hypertension, as discussed earlier in this chapter, and in improved visual acuity. This experiment demon- strates both the sensitivity of health care utilization in the general population to cost sharing and the relative insensitivity of short-term (three- to five-year) health outcomes for the general population to cost sharing. Negative Results Some studies have reported worse health status for those with health insur- ance compared to uninsured adults. This result may be attributable to the fact that
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EFFECTS OF HEALTH INSURANCE ON HEALTH 85 worse health status may lead to coverage by Medicare or Medicaid, as discussed in Chapter 2 (see Box 2.1) and Chapter 4. However, the competing hypothesis, that health insurance is not associated with overall health status, must also be consid- ered. Hahn and Flood (1995) used NMES to examine health status by both income level and type and duration of insurance coverage. When SES and demographic characteristics, health behaviors, health care utilization, and Social Security disabil- ity status were controlled for in the analysis, self-reported health status was seen to be arrayed from highest to lowest as follows: · privately insured for the full year, · privately insured for part of the year and uninsured for part of the year, · uninsured for the full year, · publicly insured for part of the year, and · publicly insured for the full year. The authors concluded that the likeliest explanation for their results was that the poorer health status of those who qualify for public coverage was not fully accounted for in their analytic model, even though qualification on the basis of disability was considered explicitly (Hahn and Flood, 1995~. An alternative (and possibly supplementary) hypothesis was that public insurance Medicaid specifi- cally provided enrollees with access and services that were less effective than those provided by private insurance. Neither of these possible explanations can be eliminated based on the research that the Committee has reviewed. A second study by Ross and Mirowsky (2000) based on the Survey of Aging, Status and the Sense of Control (ASOC) examined the claim that being uninsured contributes to the worse health of persons of lower SES. The ASOC survey included 2,600 adults between ages 18 and 95 at baseline in 1995, 38 percent of whom were 60 years or older. Participants were reinterviewed in 1998 (44 percent were lost to follow-up) (Ross and Mirowsky, 2000~. Health status, functional status, and chronic conditions reported by participants at baseline were used to predict health status, functional status, and chronic conditions three years later. Changes in these measures between baseline and follow-up were also included as predictors of health status, functional status, and number of chronic conditions at follow-up in 1998. The authors concluded that privately insured and uninsured persons had similar health status at a three-year follow-up, adjusted for baseline health status, chronic conditions, and sociodemo-graphic characteristics, and that publicly insured persons had worse health status than privately insured and unin- sured adults (Ross and Mirowsky, 2000~. The Committee does not find this study convincing in its conclusions because of both the study sample and its analytic design. The sample included a large proportion of persons over 65, all of whom have Medicare, and the substantial fraction of participants lost to follow-up differed systematically from those who were reinterviewed. By including changes in health condition over the study
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86 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE period as independent variables along with health measures at baseline, the authors may have built their findings into the predictive model itself. In addition, Medi- care beneficiaries with supplemental health insurance were classified as privately insured; thus, those who counted as publicly insured included only those Medi- care beneficiaries without supplemental policies (a lower-income subset of all Medicare beneficiaries) and Medicaid beneficiaries. This atypical classification scheme distorts the comparison between those with public and private health Insurance. CONCLUSION This chapter has presented studies examining the impact of health insurance status on general measures of population health, on health care and clinical out- comes for specific conditions, and on the appropriate use of preventive services for the nonelderly adult population in the United States. This body of research yields
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EFFECTS OF HEALTH INSURANCE ON HEALTH 87 largely consistent and significant findings about the relationship between health insurance and health-related outcomes. In summary, uninsured adults receive health care services that are less adequate and appropriate than those received by patients who have either public or private health insurance, and they have poorer clinical outcomes and poorer overall health than do adults with private health insurance. The specific findings dis- cussed throughout this chapter are presented in Box 3.12. The Committee has assessed the research regarding the effects of health insurance status across a range of health conditions and services affecting adults. In each domain examined · preventive care and screening services, · cancer care and outcomes, · chronic disease management and patient outcomes, · acute care services and outcomes for hospitalized adults, and · overall health status and mortality,
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88 CARE WITHOUT COVERAGE: TOO LITTLE, TOO LATE health insurance improved the likelihood of appropriate care and was associated with better health outcomes. Health insurance appears to achieve these positive effects in part through facilitating ongoing care with a regular health care provider and reducing financial barriers to obtaining those services that constitute or con- tribute to appropriate care, including screening services, prescription drugs, and specialty mental health services. Chapter 4 specifically addresses the question of the difference that providing health insurance to uninsured individuals and populations would make to their health and health care. The Committee assesses the potential impact of health insurance coverage on those uninsured adults who are most at risk for poor or adverse health-related outcomes, including the chronically ill, adults in late middle age, members of ethnic minorities, and adults in lower-income households. The chapter also reviews the features and characteristics of health insurance that ac- count for its effectiveness in achieving better health outcomes, including both continuity of coverage and scope of benefits.
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Representative terms from entire chapter: