To Increase Investment in Syringe Exchange

in the U.S. would be Cost-saving.Results from modeling

hypothetical syringe coverage levels

INTL AIDS CONF – WASHINGTON DC – 23 JULY 2012

T.Q. Nguyen1, B.W. Weir1, S.D. Pinkerton2, D. Des Jarlais3, D. Holtgrave1

 1Johns Hopkins Bloomberg School of Public Health, Department of Health, Behavior and Society

2Medical College of Wisconsin, Department of Psychiatry and Behavioral Medicine3Beth Israel Medical Center and North American Syringe Exchange Network

Acknowledgements• amFAR, The Foundation for AIDS Research (with funding from

the Elton John Foundation and the Irene Diamond-Tides Foundation) for supporting the Beth Israel/NASEN survey

• National Institute on Drug Abuse for supporting B.W. Weir’s training

• Johns Hopkins School of Public Health– Sommer Scholars Program for supporting T.Q. Nguyen’s

training– Department of Health, Behavior and Society– Student Conference Fund

• Researchers and organizations that have contributed to research under this topic

• Co-authors: Mr. Brian W. Weir, Dr. David Holtgrave, Dr. Don Des Jarlais and Dr. Steven Pinkerton

Federal HIV prevention budget

Total syringe

exchange programs’

budgets

Ratio:41 to 1

There is a disconnectbetween injection drug users’ (IDU) share in the HIV epidemic and funding for the effective intervention of syringe exchange.

New HIV infections in the US

heterosexual29%

IDU10%

MSM/IDU3%

MSM58%

Objective

To inform policy decisions, examine if increasing investment in syringe exchange programs (SEPs) would be cost-effective or cost-saving as an HIV prevention intervention.

Questions

What would happen to HIV incidence if SEP syringe supply were larger?How much would it cost and how much would it save?

Study synopsis:

Analysis approach

Model HIV incidence due to injection risk in hypothetical cases with higher SEP syringe coveragethan current level (base case)

Method based on Pinkerton’s model used in

Pinkerton, S.D. (2010). Is Vancouver Canada’s supervised injection facility cost-saving? Addiction. 105:1429-1436

number of new HIV infections due to drug injection risk in a yearnumber of IDUs (full-year equivalent)HIV prevalence among IDUsnumber of injections with a receptively shared (aka “borrowed”) syringe per IDU per yearproportion of syringes that are contaminated with HIVprobability of getting infected when using an HIV-contaminated syringe

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆=𝑃𝑂𝑃 (1−𝑃𝑅𝐸𝑉 ) ∙𝐵𝑂𝑅𝑅𝑆 ∙𝐶𝑂𝑁𝑇𝐴𝑀 ∙𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵

number of injections with a receptively shared (aka “borrowed”) syringe per IDU per yearnumber of new syringes from SEPs per IDU per yearnumber of new syringes from other sources per IDU per year

≤𝑩𝑶𝑹𝑹𝑺+𝑺𝑬𝑷𝑺𝒀𝑹𝑺𝒃𝒂𝒔𝒆+𝒏𝒐𝒏𝑺𝑬𝑷𝑺𝒀𝑹𝑺𝒃𝒂𝒔𝒆

𝑩𝑶𝑹𝑹𝑺+𝑺𝑬𝑷𝑺𝒀𝑹𝑺𝒉𝒚𝒑+𝒏𝒐𝒏𝑺𝑬𝑷𝑺𝒀𝑹𝑺𝒉𝒚𝒑

𝑰𝑵𝑭𝑬𝑪𝑻𝑰𝑶𝑵𝑺𝒉𝒚𝒑

𝑰𝑵𝑭𝑬𝑪𝑻𝑰𝑶𝑵𝑺𝒃𝒂𝒔𝒆

DERIVATION: Starting from equation for HIV incidence

number of new infections due to injection risk in a yearnumber of IDUs (full-year equivalent)HIV prevalenceprobability an uninfected IDU gets infected in the year𝐼𝑁𝐹𝑃𝑅𝑂𝐵=1− (1−𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵 )𝐶𝑂𝑁𝑇𝐴𝑀𝐼𝑁𝐽𝑆 ≈𝐶𝑂𝑁𝑇𝐴𝑀𝐼𝑁𝐽𝑆 ∙𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵probability of getting infected when using an HIV-contaminated syringenumber of injections using HIV-contaminated syringes per IDU per year

𝐶𝑂𝑁𝑇𝐴𝑀𝐼𝑁𝐽𝑆=𝐵𝑂𝑅𝑅𝑆 ∙𝐶𝑂𝑁𝑇𝐴𝑀number of injections with a receptively shared (aka “borrowed”) syringe per IDU per yearproportion of syringes that are contaminated with HIV

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆=𝑃𝑂𝑃 (1−𝑃𝑅𝐸𝑉 ) ∙𝐵𝑂𝑅𝑅𝑆 ∙𝐶𝑂𝑁𝑇𝐴𝑀 ∙𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵

(b/c borrowing is likely to decrease or stay the

same)

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆h𝑦𝑝

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆𝑏𝑎𝑠𝑒

DERIVATION: Comparing hypothetical case and base case

Pinkerton based on Kaplan & O’Keefe’s simplified needle circulation model:𝐶𝑂𝑁𝑇𝐴𝑀h𝑦𝑝  𝐶𝑂𝑁𝑇𝐴𝑀𝑏𝑎𝑠𝑒  

≤𝐵𝑂𝑅𝑅𝑆𝑏𝑎𝑠𝑒+𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒

𝐵𝑂𝑅𝑅𝑆h𝑦𝑝+𝑆𝑌𝑅𝑆h𝑦𝑝

number of new syringes from SEPs per IDU per yearnumber of new syringes from other sources per IDU per year

⟹𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆 h𝑦𝑝

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆𝑏𝑎𝑠𝑒≤𝐵𝑂𝑅𝑅𝑆𝑏𝑎𝑠𝑒+𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒

𝐵𝑂𝑅𝑅𝑆h𝑦𝑝+𝑆𝑌𝑅𝑆h𝑦𝑝

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆h𝑦𝑝

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆𝑏𝑎𝑠𝑒≤𝐵𝑂𝑅𝑅𝑆+𝑆𝐸𝑃𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒+𝑛𝑜𝑛𝑆𝐸𝑃𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒

𝐵𝑂𝑅𝑅𝑆+𝑆𝐸𝑃𝑆𝑌𝑅𝑆h𝑦𝑝+𝑛𝑜𝑛𝑆𝐸𝑃𝑆𝑌𝑅𝑆h𝑦𝑝

≤𝐶𝑂𝑁𝑇𝐴𝑀h𝑦𝑝  𝐶𝑂𝑁𝑇𝐴𝑀𝑏𝑎𝑠𝑒  

number of new syringes per IDU per year

¿𝐵𝑂𝑅𝑅𝑆h𝑦𝑝𝐵𝑂𝑅𝑅𝑆𝑏𝑎𝑠𝑒

∙𝐶𝑂𝑁𝑇𝐴𝑀 h𝑦𝑝  𝐶𝑂𝑁𝑇𝐴𝑀 𝑏𝑎𝑠𝑒  

¿𝑃𝑂𝑃 (1− 𝑃𝑅𝐸𝑉 ) ∙𝐵𝑂𝑅𝑅𝑆h𝑦𝑝𝐶𝑂𝑁𝑇𝐴𝑀 h𝑦𝑝 ∙𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵  𝑃𝑂𝑃 (1−𝑃𝑅𝐸𝑉 ) ∙𝐵𝑂𝑅𝑅𝑆𝑏𝑎𝑠𝑒𝐶𝑂𝑁𝑇𝐴𝑀 𝑏𝑎𝑠𝑒 ∙𝑇𝑅𝐴𝑁𝑆𝑃𝑅𝑂𝐵

Calculate:

Let vary: hyp case = proportion of drug injections “covered” by new syringes from

SEPs

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆h𝑦𝑝

𝐼𝑁𝐹𝐸𝐶𝑇𝐼𝑂𝑁𝑆𝑏𝑎𝑠𝑒≤𝐵𝑂𝑅𝑅𝑆+𝑆𝐸𝑃𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒+𝑛𝑜𝑛𝑆𝐸𝑃𝑆𝑌𝑅𝑆𝑏𝑎𝑠𝑒

𝐵𝑂𝑅𝑅𝑆+𝑆𝐸𝑃𝑆𝑌𝑅𝑆h𝑦𝑝+𝑛𝑜𝑛𝑆𝐸𝑃𝑆𝑌𝑅𝑆h𝑦𝑝

parameter value sources/basis

i # full-year equivalent IDUs in US 1.23m

based on 1992-2002 IDU pop estimation from Brady et al. (2002), adjusted for cycling in/out of injecting (based on Galai et al., 2003)

ii # injections per IDU per yr 1023 365.25 * number of injections per IDU per day

(2.8 – Lurie et al., 1998; Tempalski et al., 2008)

iii # injections with a borrowed syringe per IDU per yr

84.9based on probability of borrowing 8.3% (Pinkerton, 2011; Kaplan, 1993; consistent with NIDA CA data) & number of injections (ii.)

iv # new syringes per IDU per yr 187.6

based on number of injections (ii.), number of borrows (iii.) & number of times an IDU uses a syringe he/she owns (5 – Huo & Oullet, 2007)

v total # syringes from SEPs per yr 36.8m Beth Israel/NASEN 2009 survey (adjusted for

assumed 10% uncounted)

vi # new syringes from SEPs per IDU per yr

29.9

vii # new syringes from other sources per IDU per yr

157.7

parameter value sources/basis

viii SEP syringe coverage /base case

2.9% of injs

ix SEP cost per syringe /typical $0.72 average of 2005-2009 SEP unit costs (Beth Israel/NASEN

survey), converted to 2011 dollars

x SEP cost per syringe /minimal $0.36 assumed to be half of typical cost (Des Jarlais expert

opinion)

xirate at which SEP syringes replace non-SEP syringes

10%no data, assumed to be 10%, i.e.

xiinumber of HIV infections due to drug injection risk in the US per year

2575based on HIV incidence estimates for 2009 (CDC); assuming 1/2 IDU + 1/4 MSM/IDU categories due to injection risk (Des Jarlais expert opinion)

xiii per case HIV lifetime treatment cost $388k average lifetime treatment cost for an HIV infected person

for 2010 (CDC) converted to 2011 dollars

Minimum number of infections averted in a yearif SEP syringe coverage is raised from current level of 2.9% of injections to:Cost per additional

infection averted:

from $111k (SEP 5%)to $129k (SEP 10%) based on “typical” SEP service cost ($0.72 per syringe)orfrom $55.5k (SEP 5%)to $64.5 (SEP 10%)based on “minimal” service cost ($0.36 per syringe)

Return on investment:from 3.5 (SEP 5%)to 3 (SEP 10%)

Additional investment required per year& savings in HIV treatment costs (million 2011 USD)for each SEP syringe coverage level

TYPICAL SERVICE

MINIMAL SERVICEAdditional investment required per year& savings in HIV treatment costs (million 2011 USD)for each SEP syringe coverage level

Return on investment:from 7 (SEP 5%)to 6 (SEP 10%)

Sensitivity analysis Parameter

Main analysis

valueLower Higher

1 number of injections per IDU per day 2.8 2.5 3.1

2 borrowing probability 0.083 0.07 0.10

3 proportion SEP syringes uncounted 10% 5% 15%

4 number of times an IDU uses one own-syringe 5 4 7

5 proportion of infections due to injecting risk      in IDU category 50% 35% 65%

in MSM/IDU category 25% 20% 30%

6 replacement effect 10% 5% 15%

7 number of full-year equivalent IDUs 1.23m 1.0m 1.5m

Sensitivity analyses

Minimum Rate of Return on Investment– dollars saved per dollar invested –

2.8 2.7 2.6 2.5

2.9 3.0 3.1

based on MINIMAL service cost

based on TYPICAL service cost

BREAK-EVEN LINE

Minimum Rate of Return on Investment– dollars saved per dollar invested –

Minimum Rate of Return on Investment– dollars saved per dollar invested –

Key results (main):If increase SEP syringe coverage from current 2.9% of injections to5% – 10%Þ Avert about 170 – 500 HIV infections per yearÞ Require 19 – 64 million USD additional funding (for typical SEP

services)or 9.4 – 32 million USD (for minimal exchange service)

Þ Save 66 – 193 million USD in HIV treatment costÞ Rate of return on investment 3.5 – 3 (or 7 – 6)

Conclusion:It would be highly cost-saving to increase investment in syringe exchange in the US.

Recommendation:Syringe exchange should be made a priority in HIV prevention in the US.The ban on use of federal funding for syringe exchange should be lifted, and federal funding should be allocated to syringe exchange.

THANK YOU!