The Mortality Effects of Health Insurance
for the Near-Elderly Uninsured
Jose Escarce
David Geffen School of Medicine at UCLA and RAND
Coauthors:
Daniel Polsky, Jalpa Doshi, Susan Paddock, Liyi Cen,
Jeannette Rogowski, Willard Manning
Funding Source: NIA (R01 AG024451-01)
Background
• 46 Million Uninsured in the U.S.
– 18% of total non-elderly population
– 14.5% of near-elderly population
• Benefits of health insurance well documented
– Access to health care and use of health care services
– Health and mortality
• Hazard of mortality higher for the uninsured
– Under-65 population: HR: 1.23
– Near-elderly population: HR: 1.43
• Medicare shown to increase use of health care
services at 65
Objective
• To determine whether there is a change in
the hazard of mortality for the near-elderly
uninsured when they acquire Medicare at
age 65.
Health and Retirement Study (HRS)
• A panel study of a nationally representative
sample of people born between 1931-1941 and
their spouses
– Ages 51 to 61 in 1992
– 1992 through 2004 waves
• Study sample: Subjects alive and interviewed at
age 59/60 and in birth cohorts 1932-1937
(N=4,860)
– Avoids left-censoring bias
– Avoids attributing effect to cohorts
Sample Design
Graphical Representation of Research Design
Survival
Ipre
Ipost
ΔI=Ipost-Ipre
Upre
U
p
o
s
Δ
65
Age
t
U
=
U
p
o
s
t
-
U
p
r
e
Empirical Approach
• To implement research design:
– Use Cox proportional hazards model to
estimate hazard ratio for the uninsured
relative to the insured, both before age 65 and
after age 65 (i.e., after Medicare enrollment)
– Assess change in hazard ratio after age 65
compared with before age 65
Cox Regression Model
• Outcome variable: Days until death or censored
• Key Explanatory variables:
– Uninsured at 59/60
– Uninsured at 59/60*Medicare enrollment
• Insured—85.5%
Uninsured—14.5%
• Control Variables:
– Model 1: Age, sex, race, education, region, self-rated
general health at baseline
– Model 2: Model 1 plus income, assets, employment
status, baseline comorbidities, baseline ADLs, body
mass index, alcohol use, smoking
Selected Baseline Characteristics
Health Status (Fair/Poor)
Any ADL
Education (< HS Grad)
Total Assets (< 100,001)
Total Income (< 20,001)
Work for Pay
Insured Uninsured P-value of
N=591 difference
N=3484
<0.001
29.6%
16.1%
<0.001
47.5%
40.6%
<0.001
45.7%
17.6%
<0.001
57.2%
27.3%
<0.001
48.0%
12.4%
<.0001
50.1%
64.7%
Survival Curves by Insurance Status
Survivial Probabilty
1
0.8
0.6
Insured
0.4
Unisured
0.2
0
59
61
63
65
Age
67
69
71
Hazard Ratio for Mortality:
Uninsured Versus Insured
Unadjusted
HR
Model 1
HR
Model 2
HR
Uninsured vs.
Insured (before 65)
1.92**
1.45*
1.25
Uninsured vs.
Insured (after 65)
1.86**
1.41*
1.32
* p<.05, ** p<.01
Sensitivity Analyses
• Turn Medicare indicator “on” at age 65.5, 66, or
66.5 instead of 65 (to capture lagged effects of
Medicare on mortality)
• Use time-varying health status measures as
explanatory variables
• Results: No change in findings
Conclusions
• People who are uninsured in late middle age
have higher mortality rates than their insured
counterparts
• This difference in mortality rates is partly
explained by other characteristics of the two
groups
• The magnitude of the difference between the
two groups is unchanged after the uninsured
enroll in Medicare at age 65
– This finding is robust to a wide range of sensitivity
analyses
Implications
• For people who are uninsured in late middle
age, Medicare may come too late to make a
difference in their health and mortality
trajectories
• Whether those trajectories can be modified
through earlier receipt of insurance is a crucial
question
– The insured and uninsured in late middle age differ on
a range of personal characteristics that are correlated
with health
Sample Design
Background
• Medicare increases use of health care services
at 65
– Preventive services
– Doctor visits and hospital admissions
– Greater increases in health care service use among
the previously uninsured
• Effect of Medicare on health
– Enactment of Medicare
• No aggregate impact on mortality
• Reduction in mortality
– Medicare at 65 for the uninsured
• No significant improvement in health status relative
to the insured
Uninsured Hazard of Mortality
from Cox Proportional Hazard Model
Unadjusted
Hazard Ratio
Adjusted
Hazard Ratio
Uninsured
1.920*
(1.434, 2.570)
1.248
(0.901, 1.729)
Uninsured*Medicare
0.97
(0.654, 1.439)
1.056
(0.703, 1.584)