摘要：Objectives. We sought to determine the extent of HIV testing among urban injection drug users (IDUs) to assess whether an expansion of targeted testing programs would be consistent with national goals to identify previously undetected infections. Methods. IDUs in 5 US cities (Oakland, Calif; Chicago, Ill; Hartford and New Haven, Conn; and Springfield, Mass) were recruited either by chain referral or time–location sampling. The IDUs were questioned about HIV testing, and factors associated with HIV testing were analyzed. Results. Ninety-three percent of 1543 IDUs had been tested. Among those tested but who did not report having been told that they were HIV seropositive, 90% had been tested within the past 3 years. Women and syringe-exchange customers were more likely to have been tested ever and in the recent past. We estimated the number of undetected infections among urban IDUs in the United States to be less than 40000. Conclusions. Testing for HIV has reached the vast majority of IDUs through the current options. Expending scarce prevention money to expand testing of IDUs is unlikely to be productive. Instead, resources should be used for proven HIV-prevention strategies including syringe exchange, drug treatment, and secondary prevention for those who are HIV positive The Centers for Disease Control and Prevention (CDC) has estimated that there are between 850 000 and 950 000 people living with HIV in the United States. 1 It is further estimated that there have been about 40000 new infections and about 40000 new cases of AIDS yearly since 1997. 2 The introduction of effective antiretroviral therapy in the mid-1990s has had an enormous impact on the epidemic, decreasing the number of deaths attributed to AIDS to between 10000 and 20000 annually since 1997. Thus, the number of people living with HIV and AIDS has been steadily increasing. Unfortunately, there appears to be a testing gap that is leaving many people who are infected with HIV unaware of their status for long periods during which they may transmit the virus to others. Current estimates are that approximately 1 in 4 of those infected with HIV, as many as a quarter of a million people, do not know that they are infected. 1 Among the groups at highest risk for HIV infection are injection drug users (IDUs). Data from the CDC indicate that slightly more than one quarter of the 920 000 AIDS cases diagnosed through 2003 were attributed solely to injection drug use. 3 For the last 3 years with available data (2001–2003), however, the percentage of AIDS diagnoses and HIV infections attributable to injection drug use has been declining. New AIDS cases attributable solely to injection drug use comprised 23.1% of the total newly reported AIDS cases; new HIV diagnoses comprised only 16.1% of the total new HIV diagnoses, although this number may be an underestimate because many locations with large numbers of IDUs have not yet instituted named HIV reporting. 3 Nevertheless, HIV prevalence among IDUs remains high. Data from 16 sites nationwide found the overall prevalence was 12.7%. 4 Testing of IDUs for HIV infection is important for surveillance and prevention. Given 2 recent policy shifts, it is equally important to document whether a testing gap exists for IDUs. The first shift is a new CDC strategy for HIV prevention first announced in the spring of 2004. 5 This new approach, “Advancing HIV Prevention,” is part of an initiative to promote early detection of those who are infected with HIV, to enhance their referral into care, to focus prevention on persons living with HIV, and to expand prevention efforts for persons at high risk of becoming infected. Testing for HIV is a central feature of the initiative. The CDC envisions expanded testing as the first step in reducing transmission and bringing the infected into care. It based this decision on the high percentage of high-risk individuals who are infected but have not been tested, are therefore unaware of their HIV serostatus, and are more likely than those diagnosed to engage in unsafe sex. 6 – 9 The second shift is toward routine testing for HIV. Impetus for this comes from a pair of articles and an editorial published in 2005 in the New England Journal of Medicine . 10 – 12 Paltiel et al. used a cost-effectiveness analysis to demonstrate that expanded testing would have its greatest impact for the least cost when provided to high-risk populations with unknown HIV prevalence in excess of 3% and when such individuals are tested once every 3 years. 11 Life expectancies for those with HIV infection would be increased at costs well within the bounds established for cost-effective care. An alternative set of recommendations was made by the US Preventive Services Task Force, which emphasized expanded testing for high-risk groups rather than routine testing. 13 Implicit in the calls for routine testing and expansion of testing for high-risk groups is the assumption that the percentage of high-risk individuals who do not know that they are infected is high. However, before the CDC expends its scarce resources on testing programs targeted to IDUs, it is important to determine whether expanded testing of IDUs will be effective in identifying more IDUs infected with HIV. We analyzed data collected from IDUs in 5 cities—Hartford and New Haven, Conn; Springfield, Mass; Chicago, Ill; and Oakland, Calif—to examine the extent of HIV testing among active IDUs and identify factors associated with testing and test results. These data can prove useful in determining how the CDC should implement its “Advancing HIV Prevention” program.
