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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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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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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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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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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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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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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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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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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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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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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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NOTES
Representative terms from entire chapter:
privately insured
