Effect of Cost-Sharing on Screening
Mammography in Medicare Managed
Care Plans
Amal Trivedi, MD, MPH
William Rakowski, PhD
John Ayanian, MD, MPP
2007 AcademyHealth Annual Research Meeting
Background




Cost-sharing affects nearly every American with
health insurance
Copayments reduce moral hazard to “overconsume”
health care with full insurance
May also reduce use of appropriate preventive care
Several well-known studies of cost-sharing have
excluded the elderly
Objectives
To determine the prevalence of mammography
cost-sharing in Medicare health plans
To understand the impact of cost-sharing on the
appropriate use of mammography
To assess effects of mammography cost-sharing
on vulnerable population groups
Sources of Data

2001-4 Medicare HEDIS data

2001-4 Medicare enrollment file

2001-4 CMS health plan benefit data

2004 Interstudy Competitive Edge database
Study Population



Included women age 65-69 who had been
assessed for the HEDIS breast cancer screening
indicator
Excluded women who died during the
measurement year
Final study population: 366,475 women in 174
health plans
Variables



Independent variable: enrollment in a plan with
>$10 or >10% coinsurance for screening
mammography
Dependent variable: receipt of a biennial
screening mammogram
Covariates:
Individual-level: race (black, white, other), zip code
level income and education, buy-in eligibility, year
 Plan-level: census region, model type, plan size, plan
age, tax- status

Analyses - Main Sample



Assessed characteristics of enrollees and breast
cancer screening rates in cost-sharing and fullcoverage plans
Constructed multivariate regression models
adjusting for individual and plan covariates and
clustering by plan
Included interactions of cost-sharing with
income, education, race and buy-in eligibility
Analyses - Subsample

Identified seven plans that changed from full coverage
to cost-sharing

Performed a difference-in-difference analysis by
comparing longitudinal changes in screening compared
to 14 matched control plans

Plans matched based on:



Census region
Profit-status
Model type
Trends in Mammography Cost-sharing
Year
# of plans
(N=174)
% of women in
cost-sharing
plans
2001
3
0.5
2002
10
4.3
2003
11
4.8
2004
21
11.4
Median copayment $20 (Range $13-$35)
5 plans charged 20% coinsurance
Characteristics of Enrollees in Cost-Sharing
and Full Coverage Plans
Cost-Sharing
Age (y)
67.1
Black (%)
23
Below Poverty (%)
11
College Attendance (%)
32
Buy-in (%)
10
Full Coverage
67.1
10
9
35
7
Screening Rate (%)
Breast Cancer Screening Rates in CostSharing and Full-coverage Plans
100
90
80
70
60
50
40
30
20
10
0
76.7
65.7
2002
78.2
77.5
70
69.7
2003
Cost-sharing
Full coverage
2004
Adjusted Impact of Cost-sharing on
Screening Mammography
Effect of Costsharing
Unadjusted
Adjusted for SES,
plan characteristics,
and clustering by
plan
95% CI/p
-8.3%
-7.2%
-9.7%, -4.6%
P<0.001
* Cost-sharing had the largest effect on
mammography of any of the plan covariates
in the model
Adjusted Effect of Cost-sharing by Income and Education
0.0%
-2.0%
-4.0%
-4.7%
-6.0%
-8.0%
-8.3%
-5.5%
-7.5% -7.7%
-10.0%
-12.0%
-11.8%
Education
P<0.001 for trends
Income
Low
Medium
High
Mammography Rates in plans that instituted costsharing compared to matched controls
2002
Added costsharing
74.8%
Maintained
full coverage
71.9%
2004
Change
∆-∆
Adjusted
∆-∆
Mammography Rates in 7 Plans that Instituted Costsharing in 2003 Compared to 14 Matched Control Plans
2002
2004
Change
Added
costsharing
74.8%
69.3%
-5.5%
Maintained
full
coverage
71.9%
75.3%
+3.4%
Mammography Rates in 7 Plans that Instituted Costsharing in 2003 Compared to 14 Matched Control Plans
2002
2004
Change ∆-∆
Added
costsharing
74.8%
69.3%
-5.5%
Maintained
full
coverage
71.9%
75.3%
+3.4%
-8.9%
Adj.
∆-∆
Mammography Rates in 7 Plans that Instituted Costsharing in 2003 Compared to 14 Matched Control Plans
2002
2004
Change
∆-∆
Added costsharing
74.8%
69.3%
-5.5%
-8.9% -8.8%
Maintained
full coverage
71.9%
Adj.
∆-∆
(-4.0, -13.6%)
P=0.002
75.3%
+3.4%
Limitations





Women not randomly assigned to cost-sharing
plans
Unable to analyze differential impacts of
specific copayment amounts
Lacked information on rescreening
Zip-code proxies for income and education
Limited to Medicare managed care
Conclusions



Copayments of >$10 or coinsurance of >10%
associated with lower rates of breast cancer
screening
Cost-sharing disproportionately affects
vulnerable populations
Prevalence of cost-sharing is dramatically
increasing in Medicare managed care
Implications



Cost-sharing should be tailored to the
underlying value of the health service
Eliminating copayments may increase adherence
to appropriate preventive care
Important implications for Medicare FFS, where
enrollees without supplemental coverage face
20% coinsurance
Moral Hazard
“If your office gives you and your co-workers all the
free Pepsi you want—if your employer, in effect, offers
universal Pepsi insurance—you’ll drink more Pepsi than
you would have otherwise.”
- Malcolm Gladwell
“The Myth of Moral Hazard”, in
The New Yorker, August 29, 2005
Study Population
24,468,528 observations in HEDIS data from 2001-4
Matched to Enrollment File (97% match rate)
23,656,038 observations
Excluded males, enrollees not between 65-69,
persons who died in measurement year, and
observations from 2001
2,189,983 observations from 178 plans from 2002-4
Linked to Interstudy database; excluded four
plans where Interstudy data not available
2,143,556 observations from 174 plans
Excluded enrollees who were not assessed for
HEDIS mammography measure
550,082 observations (366,475 enrollees)
Health Plan Characteristics of Enrollees in
Cost-Sharing and Full Coverage Plans
Cost-sharing
Full coverage
South
36%
16%
West
21%
41%
Staff/Group
Model
For-profit
7%
18%
72%
56%
Adjusted Negative Effect of Cost-sharing by Race and
Medicaid Eligibility
0.0%
-2.0%
Yes
No
White
Black
-3.7%
-4.0%
-6.0%
-6.8%
-7.8%
-8.0%
-10.0%
-12.0%
-14.0%
-13.4%
Medicaid
P<0.001 for trends
Race