Is Dual Use Associated With
Excess Mortality in VA Patients
With Atrial Fibrillation?
Ciaran S. Phibbs, PhD
Veterans Affairs Palo Alto Health
Care System and Stanford University
Co-authors
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Susan Frayne, Study PI
Paul Heidenreich
Tyson Holmes
Stephanie Le
Rudy Moos
Susan Schmitt
Mintu Turakhia
Atrial Fibrillation and Warfarin
A-fib fairly common cardiac condition
that significantly increases stroke risk.
 Unless contra-indicated, guideliness
recommend anti-coagulation therapy.
 Standard is Warfarin. Effective, but
difficult to manage. Lots of drug and
dietary interactions.
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Warfarin Monitoring
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Because Warfarin has so many
interactions, need to monitor (INR)
carefully.
– Risks both ways. Under-medicated
increases stroke risk.. Over-medicated
increases bleeding risk.
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Standard for stable patients is to
monitor every 4 weeks.
Dual Use
Dual use (using both VA and non-VA
services) is common among VA users.
 Given complexities of managing
patients on Warfarin, dual use of this
monitoring could well increase patient
risk.
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Our Study, Pilot Dual Use Study
We are currently conducting a study of
management of VA A-fib patients,
comparing those with and without
mental health conditions.
 Have Medicare data for this study.
 Created opportunity to look at dual
use.
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Data
VA PTF files
 VA NPCD (OPC) SE files
 VA Fee-Basis files
 VA DSS LAB and LAR files
 Medicare data from VIREC
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Cohort
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VA users
At least one diagnosis of A-fib in 02, with
confirmation in 03. Could be VA,
Medicare, or VA fee basis.
Regular VA users, at least one face-to-face
provider visit in 02, 03, & 04
Limited to VA facilities with “good” INR
data
Received at least 1 VA Warfarin
prescription in FY 04
DATA
55,307 patients in the cohort
 31% of these patients had at least one
INR done by both VA and Medicare.
Dual use INR monitoring
 17% had only Medicare INR
monitoring, even though Warfarin is
from the VA
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Dual use is dynamic
Time Interval Dual use for any Dual Use Based
of Records
outpatient care on >=1 INR
Test in
Medicare
FY04 Q1-Q4
73%
48%
FY04 Q3-Q4
57%
42%
FY04 Q4
36%
27%
Unadjusted Mortality
VA INR
Only
Unadjusted
Mortality
4.0%
VA &
Medicare
INR
Medicare
INR Only
5.6%
5.8%
Adjusted Mortality
VA INR
Only
Unadjusted
Mortality
OR for Age
Adjusted
Mortality
4.0%
Ref
VA &
Medicare
INR
Medicare
INR Only
5.6%
5.8%
1.24
1.25
(1.13-1.36) (1.11-1.39)
Conclusions
Dual use is common, even for
management of complex
patients/conditions such as INR
monitoring for patients on Warfarin.
 Dual use for INR monitoring is
associated with a significant increase in
1-year mortality.
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Implications
This work needs to be refined, we only
age-adjusted.
 Mortality is a crude outcome measure,
the results imply that further
investigation will find other differences
in the quality of anti-coagulation
management.
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Implications
When care is split across providers,
quality of care suffers.
 Care coordination is probably the
biggest problem.
 An electronic medical record system
that can be integrated across providers
could potentially address much of this
problem (but probably not all of it).
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