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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 QuickTime™ and a decompressor are needed to see this picture. • k = flow of people turning 15 • g = rate at which people not interested in tattoos = annual rate of getting tattoos QuickTime™ and a decompressor are needed to see this picture. = 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 QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. 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 QuickTime™ and a decompressor are needed to see this picture. Uncertainty in QuickTime™ and a decompressor are needed to see this picture. Is a dynamic model needed? QuickTime™ and a decompressor are needed to see this picture. 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… QuickTime™ and a decompressor are needed to see this picture.