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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
s
So

Ao
A
rCS
rAS
rAC
Co
C
s
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• k = flow of people turning 15
• g = rate at which people not interested in tattoos
  = annual rate of getting tattoos
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  = 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
t=(At+Ct)/(St+At+Ct)
=(Ao+At+Co+Ct)/total
s
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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)) ·/
Base Case
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Uncertainty in 
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Is a dynamic model needed?
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Conclusion and Discussion
• Regulating tattoo parlors is cheap and costeffective
• 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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