HCV Transmission and Tattoo Parlors

• Is it cost-effective to regulate tattoo parlors to reduce the spread of HCV?

• At what prevalence level is it cost-effective?

HCV

• 3.1% of world infected with HCV– 20% of recruits in Egypt

• Expected to kill more Americans than HIV

• Transmitted through blood– Transfusions, sex, mother-child, unsterilized medical

equipment, injection drug use, …– Most frequently through needle sharing

(developed countries)– Transfusion now screened

• What about tattooing?– Conflicting data.

Model

• Compartmental infectious disease model– With costly control

• Similar to HIV but– HCV more infectious– HCV infection less costly

• Considers both tattoo and non-tattoo modes of transmission– Not additive

States

• 3 health states– S = Susceptibles– A = Acute infection– C = Chronic infection

• 2 social states– t = visits tattoo parlors– o = doesn’t

• 6 total states: So,St,Ao,At,Co,Ct

Non-tattooed population

A, C death rates

• rAS, rAC, rCS transition rates

S death+turning 50

= overall prevalence rate of non-tattoo transmission

• Time in years• Population = age 15-50

So

Ao Co

s

rAS

rAC

rCS

A C

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s

• k = flow of people turning 15• g = rate at which people not interested in tattoos = annual rate of getting tattoos

= P(infection | infected equipment) = P(equipment infected) = ·f(t)

= P(use of equipment on HCV+ person infects equipment)

• f(t) = P(use of equipment on HCV+ person)– Typically equipment used 5 times before replaced

– f(t) = (1/5) ∑i=0..4 1-(1-t)i

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s

t=(At+Ct)/(St+At+Ct)=(Ao+At+Co+Ct)/total

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Control

• Control is sterilization of equipment = 0 (or close to)

• Time = time of regulation

– T = planning horizon (15 years in baseline)

• Discounting (3% in baseline)• Outcomes

(,T) = total discounted number of sterilizations

– I(,T) = total discounted number of infections

Cost-effectiveness

• Cost = cost of sterilization = cost infection– Not really accounting for health quality

• Regulate at time t2 versus t1

• Benefit/Cost ratio [$]/[$]– BC(t1,t2) = (I(t2,T)-I(t1,T))/(S(t2,T)-S(t1,T)) ·/

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Base Case

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Uncertainty in

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Is a dynamic model needed?

Conclusion and Discussion

• Regulating tattoo parlors is cheap and cost-effective

• Doesn’t capture averted secondary infections beyond horizon

• More tattoos () may decrease BC• Dynamic model crucial to capturing secondary

infections

• Would an age structured model make sense?• What about HIV?

Next Time

Network models: the effect of reducing concurrency on HIV transmission…

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