Transcript Document

Cost Effectiveness of Maintenance
Treatment for Heroin Addicts
Professor Margaret Brandeau
Department of Management Science and Engineering
with
Greg Zaric, U. Western Ontario
Paul Barnett, Palo Alto VA
Drug Abuse Treatment
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Outline of Talk
• Background
• Model of maintenance therapy for opiate addiction
and HIV prevention
• Results – methadone
• Results – buprenorphine
• Other relevant issues
Drug Abuse Treatment
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Introduction
• 1-1.5 million IDUs in U.S.
• High prevalence of HIV among IDUs (5-40%)
• One-third of new HIV cases due to IDUs
• New laws require treatment instead of jail time
Drug Abuse Treatment
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Methadone maintenance
• Addicts receive daily doses of methadone
• Methadone treatment slots only for 15% of IDUs
• Average wait to enter treatment is 6 months
• Expansion of MMT is controversial
• Many health care sponsors (e.g., Medicaid) do not
cover MMT
• Eight states prohibit methadone
Drug Abuse Treatment
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Methadone in the news
• “Mayor Wants To Abolish Use of Methadone”
• “Methadone: A Cure or an Addiction?; Giuliani Is
Right”
• “Few Successes to Back Mayor’s Methadone Limits”
(NY Times, 8/25/98)
• “Federal Proposal Would Provide Methadone to More
Drug Addicts” (NY Times, 9/29/98)
Drug Abuse Treatment
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Buprenorphine maintenance
• Buprenorphine may be safer than methadone
• Low abuse potential; daily dispensing not required
• Less effective than methadone in reducing risky
behavior
• Widely used in France
• Not approved for maintenance treatment in U.S.
• No price set
Drug Abuse Treatment
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Potential benefits of
maintenance treatment
• Reduced HIV transmission
• Reduced mortality and comorbidities associated with
injection drug use
• Increased quality of life
• Reductions in cost of HIV care and other health care
• Reductions in cost of social programs
Drug Abuse Treatment
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Potential drawbacks of
maintenance treatment
• Maintenance treatment is costly - $5,000+ / year
• HIV-infected individuals in maintenance treatment
are more likely to receive expensive HIV treatment
• Maintenance treatment does not induce complete
abstinence from risky behavior
• Average stay in treatment is 2 years
• 90% of those leaving treatment resume injection drug
use!
Drug Abuse Treatment
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Policy questions
What is the cost effectiveness of expanding existing
methadone maintenance programs in the U.S.?
What would be the cost effectiveness of
buprenorphine maintenance treatment in the U.S.,
as a function of its price?
Drug Abuse Treatment
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Methods
• Dynamic model of HIV transmission
• Two scenarios: High (40%) and low (5%) HIV
prevalence among IDUs
• Assumed modest increases in maintenance treatment
capacity
– Methadone: 10% increase
– Buprenorphine: 10% increase
• All slots incremental
• 5% net expansion
Drug Abuse Treatment
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Methods (cont.)
• Estimated total costs and health benefits over a
10-year time horizon (societal perspective)
• Costs: all health care costs
• Benefits: QALYs gained
• Calculated incremental CE ratios
Drug Abuse Treatment
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Simplest epidemic model
Uninfected
Persons, X(t)
Infected
Persons, Y(t)
dY/dt = aY(t)[N + 1 - Y(t)]
where: Y(0) = 1
Y(t) = [N+1]/[1 + Ne-a(N+1)t]
a = sufficient contact rate
X(t) + Y(t) = N + 1
Number of Infected
Persons at Time t, Y(t)
t
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Schematic of dynamic model
Not Infected
IDUs
Methadone
Maintenance
Treatment
Non-IDUs
Drug Abuse Treatment
IDU
IDU, MMT
Non-IDU
HIV-Infected
IDU,
HIV+
IDU, MMT
HIV+
Non-IDU
HIV+
AIDS
IDU,
AIDS
IDU, MMT
AIDS
Non-IDU
AIDS
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


9
Uninfected IDUs,
j(t)
j=1
Not in Treatment
X1(t)
(t)
HIV-Infected IDUs,
Not in Treatment
X2(t)
(t)
(t)
(t)
(t)

IDUs with AIDS,
Not in Treatment
X3(t)

(t)
(t)

j=1
HIV-Infected IDUs,
In Treatment
X5(t)
(t)
(t)
(t)
9
Uninfected
Non-IDUs
X7(t)

Drug Abuse Treatment
j(t)
j=1
HIV-Infected
Non-IDUs
X8(t)

(t)


IDUs with AIDS,
In Treatment
X6(t)
(t)


Non-IDUs
with AIDS
X9(t)
AIDS Deaths
(t)
j(t)
(t)

9
Uninfected IDUs,
In Treatment
X4(t)

(t)


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Epidemic model
equations
Size of compartment 4
(IDUs in MMT)
Size of compartment 7
Size of compartment 1
(general population)
(IDUs not in MMT)

9
X 1 (t )  71 (t ) X 7 (t )  41 (t ) X 4 (t )  X 1 (t )(17 (t )  14 (t )   1  1 )  X 1 (t ) 1 j (t )
j 1
Migration rates
Change in number of
Mortality rate
IDUs not in MMT

Maturation
rate
New HIV
Infections
9
X 2 (t )  82 (t ) X 8 (t )  52 (t ) X 5 (t )  X 2 (t )(28 (t )  25 (t )   2   2   2 )  X 1 (t ) 1 j (t )
j 1

X 3 (t )  93 (t ) X 9 (t )  63 (t ) X 6 (t )   2 X 2 (t )  X 3 (t )(39 (t )  36 (t )   3  3  3 )
Drug Abuse Treatment
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etc...
Model inputs
•
•
•
•
•
•
•
•
Drug injection behavior (in/out of treatment)
Sexual behavior
HIV transmission rates
HIV progression rates
Mortality rates
Quality-of-life estimates
Cost per maintenance treatment slot
All other health care costs
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Methadone assumptions
• Methadone maintenance cost: $5250/IDU/year
• Methadone maintenance effectiveness:
– 80% reduction in injection frequency
– 70% reduction in sharing
– 65% annual retention rate
– 3.5% annual graduation rate
Drug Abuse Treatment
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Other data
• Non-HIV death rates
Untreated IDUs – 3%
IDUs in MMT – 1.13%
Non-IDUs – .14%
• Progression rates from HIV to AIDS
Untreated IDUs, and non-IDUs – .0087
IDUs in MMT – .0082
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Cost and quality of life
Uninfected
HIVInfected
AIDS
Untreated
IDUs
$3,850
(.80)
$8,653
(.72)
$36,401
(.42)
MMT
$8,261
(.90)
$18,806
(.81)
$40,812
(.48)
Non-IDUs
$1,210
(1.00)
$6,013
(.90)
$33,761
(.53)
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Results:
Methadone maintenance
High-Prevalence Low-Prevalence
Community
Community
Methadone cost
$17.0 m
$4.8 m
Net cost
$10.9 m
$3.3 m
1300
301
$8,200
$10,900
QALYs gained
CE ratio
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CE of other HIV interventions
• HIV treatments (cost/QALY gained)
– PCP prophylaxis: $16,000
– MAC prophylaxis: $35,000-$74,000
– CMV retinitis prophylaxis: $160,000
• HIV prevention
– Post-exposure prophylaxis: $37,000 after occupational
exposure; $6,300 after sexual exposure
– Incr. condom use among high-risk women: $2,000
– Skills training for gay men: Cost saving
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Cost of 100 new slots ($1000’s)
High-Prevalence Low-Prevalence
Community
Community
Methadone
4538
4538
HIV care – IDUs
-970
-540
HIV care – non-IDUs
-321
-323
Other health – IDUs
-569
-796
Other health – non-IDUs
241
242
Total cost
2919
3121
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Benefits of 100 new slots ($1000’s)
High-Prevalence Low-Prevalence
Community
Community
Infections averted – IDUs
51
20
Infections averted – non-IDUs
19
12
QALYs – IDUs
149
81
QALYs – former IDUs
28
46
QALYs – never IDUs
178
160
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Results of sensitivity analysis
MMT cost effective even if:
• New slots are twice as costly and half as effective
as existing slots
• No reduction in quality of life for IDUs
• IDUs receive a quality-of-life adjustment of zero
• Only life years are measured
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Conclusions:
Methadone maintenance
• Expansion of methadone maintenance treatment
is cost effective relative to commonly accepted
criteria
• Significant benefits of methadone maintenance
programs accrue to non-IDUs
• Barriers to methadone maintenance may restrict
access to a cost-effective medical intervention
Drug Abuse Treatment
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Buprenorphine assumptions
• Buprenorphine maintenance cost:
– $5700, $9400, $14,900/IDU/year
• Buprenorphine maintenance effectiveness:
–
–
–
–
73% reduction in injection frequency
64% reduction in sharing
65% annual retention rate
2.8% annual graduation rate
Drug Abuse Treatment
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CE ratios:
Buprenorphine maintenance
$5/Dose
$15/Dose $30/Dose
High-prevalence community
$10,800
$20,500
$35,000
Low-prevalence community
$14,000
$26,000
$44,200
High-prevalence community
$14,000
$35,100
$66,700
Low-prevalence community
$17,700
$44,500
$84,700
All Slots incremental:
5% Net Expansion:
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Results of sensitivity analysis
• Buprenorphine cost effective if:
– High value assigned to treatment benefit
– Low value for treatment benefit, low price
• Buprenorphine not cost effective if:
– No value assigned to LYs of IDUs or those in
treatment, and high price
– Many IDUs switch from MMT to buprenorphine
Drug Abuse Treatment
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Conclusions:
Buprenorphine maintenance
• At $5/dose, buprenorphine maintenance treatment
is cost effective
• Buprenorphine is cost effective at $15/dose only if
its adoption does not lead to a decline in MMT
• Buprenorphine is not likely to be cost effective if
the price is $30/dose
Drug Abuse Treatment
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Other relevant issues
• Reductions in cost of social programs
• Reductions in spread of other diseases (Hepatitis B
and C, TB, other STDs)
• Networks of IDUs
• Characteristics of IDUs enrolled in the incremental
treatment slots
• Legal, philosophical and moral concerns
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Update
• MMT programs
– Expansion in some areas
– Budget cutbacks in some states
– “Wait for Methadone Puts Hundreds of Lives
on Hold” (Seattle PI, 3/17/03)
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Update
• Buprenorphine approved by FDA in October, 2002
– Schedule III drug
– Prescribed in doctor’s office
– 30-day prescriptions
– Cost/dose ~ $5
– Medicare coverage: on a state-by-state basis
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