Impact of Medicare Coverage
on Basic Clinical Services
for Previously Uninsured Adults
J. Michael McWilliams, MD
Alan M. Zaslavsky, PhD
Ellen Meara, PhD
John Z. Ayanian, MD, MPP
ies in which unmeasured factors asso-
dividuals’ preferences for health care,
could have explained observed differ-
gitudinal studies would help to re-
dress these limitations of prior cross-
sectional research and to define more
clearly the effects of health insurance
care of people who gain or lose insur-
uninsured adults through comparison
on this topic have demonstrated that
loss of health insurance is associated
riers to care,8,9and retention of insur-
overall health and physical function-
NINSURED ADULTS IN THE
cess to needed health care
services, receive less appro-
Primary Care, Department of Medicine, Brigham and
Women’s Hospital and Harvard Medical School (Drs
McWilliams and Ayanian), and Department of Health
Zaslavsky, Meara, and Ayanian), Boston, Mass; and
the National Bureau of Economic Research, Cam-
bridge, Mass (Dr Meara).
Corresponding Author and Reprints: John Z. Aya-
02115 (e-mail: email@example.com).
consequences than insured adults. Longitudinal studies would help to more clearly de-
fine the effects of health insurance on health care and health.
Objective To assess the differential effects of gaining Medicare coverage on use of
basic clinical services and medications by previously insured and uninsured adults.
and Retirement Study were used to analyze differences in receipt of basic clinical ser-
vices by adults in 1996 and 2000, before and after becoming eligible for Medicare at
age 65 years.
Participants A total of 2203 adults aged 60 to 64 years in 1996 who were classified
as continuously uninsured (n=167), intermittently uninsured (n=216), or continu-
ously insured (n=1820) in 1994 and 1996, prior to Medicare eligibility.
mography (in women), prostate examination (in men), and treatment of arthritis and
hypertension in the prior 2 years.
Results The difference in cholesterol testing between continuously insured and con-
tinuously uninsured adults was significantly reduced after Medicare eligibility (35.4%
vs 17.7%; change of −17.7% [95% CI, −29.3% to −6.2%]; P=.003), and the reduc-
tion was substantially greater among those with hypertension or diabetes than among
Differences in use were similarly reduced after Medicare eligibility for mammography
and prostate examination in men (45.2% vs 20.0%; change of −25.2% [95% CI,
−45.4% to −5.1%]; P=.01). Continuously uninsured adults with arthritis reported sig-
nificantly greater increases in arthritis-related medical visits and limitations of activity
than continuously insured adults after Medicare eligibility, but not greater increases in
arthritis treatments. Among adults with hypertension, differences in use of antihyper-
tensive medications between continuously uninsured and insured adults were essen-
tially unchanged after Medicare coverage.
Conclusions Previously uninsured adults substantially increased their use of cov-
ered basic clinical services but not medications after gaining Medicare coverage. An
affordable option through which near-elderly uninsured adults could purchase Medi-
care coverage might have similar effects.
For editorial comment see p 816.
©2003 American Medical Association. All rights reserved.
(Reprinted) JAMA, August 13, 2003—Vol 290, No. 6
are uninsured has also grown recently,
impact of disparities in health care be-
tween insured and uninsured near-
elderly adults. Our findings demon-
insured adults, as well as the potential
use of basic clinical services.
Author Contributions: Study concept and design:
McWilliams, Zaslavsky, Meara, Ayanian.
Acquisition of data: McWilliams.
Analysis and interpretation of data: McWilliams,
Zaslavsky, Meara, Ayanian.
Drafting of the manuscript: McWilliams.
Critical revision of the manuscript for important in-
tellectual content: McWilliams, Zaslavsky, Meara,
Statistical expertise: McWilliams, Zaslavsky, Meara,
Obtained funding: Ayanian.
Administrative, technical, or material support:
Study supervision: Ayanian.
Funding/Support: This study was supported by the
Primary Care Research Fund of Brigham and Wom-
en’s Hospital and by grant 20010558 from the Com-
monwealth Fund, New York, NY.
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MEDICARE FOR PREVIOUSLY UNINSURED ADULTS
JAMA, August 13, 2003—Vol 290, No. 6 (Reprinted)
©2003 American Medical Association. All rights reserved.