COST EFFECTIVENESS OF SCREENING FOR ACUTE HIV AND HCV INFECTION IN INJECTION DRUG USERS

Purpose: The injection drug user (IDU) population continues to experience epidemic rates of new HIV and hepatitis C (HCV) infections.  Detection of new infections during the acute phases of these diseases may provide an opportunity to improve patient outcomes and change the course of these epidemics.  We aimed to compare the effectiveness and cost effectiveness of various screening protocols and frequencies of screening for acute and chronic HIV and HCV infection among IDUs in opioid replacement therapy (ORT).

Method:   We developed a dynamic compartmental model of the HIV and HCV epidemics for a population of IDUs and non-IDUs in a representative U.S. urban center with 2.5 million adults.  We assumed that 6.5% of IDUs were HIV-positive and 35% were HCV-positive.  We considered strategies of screening individuals in ORT for either or both infections in either the chronic (by antibodies) or the acute (by viral RNA) phases of infection at frequency intervals of only on entry to ORT, annually, twice annually, every 3 months, and monthly.  Outcomes included the number of HIV and HCV infections, quality-adjusted life-years, costs, and incremental cost effectiveness ratios.  Costs and benefits, including infections averted, were discounted at 3% annually.

Result:   We estimate that with no incremental screening, 9,900 HIV and 16,600 HCV infections would occur in this population over 20 years.  Antibody screening for both HIV and HCV upon entry to ORT would avert 67 HIV infections and 203 HCV infections.  Adding testing for acute HIV and HCV infection to antibody screening protocols can incrementally avert hundreds of HIV infections but fewer than 10 additional HCV infections over 20 years.  Strategies of acute HIV screening every 3 months have incremental cost-effectiveness ratios of less than $50,000 per QALY gained and were robust in sensitivity analysis.

Conclusion:   Frequent screening of a relatively small group (only IDUs in ORT) for acute HIV infection and initiation of treatment with ART during this period appears cost effective and may influence the course of the epidemic.  Screening for acute HCV infection was not cost effective in any scenario.