The low prevalence of anti-HCV among non-IDU MSM compared with other non-IDU men in this study is consistent with findings from other studies. Although a study published in the early 1990s suggested that a higher prevalence of HCV infection in MSM (6.9%) compared with heterosexual subjects (1.0%) attending a genitourinary clinic in London was strong evidence of sexual transmission of HCV among MSM, the study did not account for a history of injection drug use.
18 A larger, more recent study in genitourinary clinics in the United Kingdom, using similar methods, found a low prevalence of anti-HCV among non-IDU, with the anti-HCV prevalence in MSM not significantly different from non-MSM (0.92% vs. 0.75%, PR 1.23; 95% CI 0.76, 1.98).
19 The prevalence of HCV infection among MSM in STD clinics has generally been found to be no higher than among heterosexuals.
6–8 Only one study of STD clinic clients found male homosexual activity to be an independent risk factor for HCV infection, but this association became nonsignificant when HIV infection was included in the multivariate model.
20A limitation of the current study is that MSM who seek services in publicly funded STD or HIV CTS may not be representative of MSM in general. However, there is no reason to believe that MSM who seek care in the private sector are more likely to engage in behaviors that may put them at increased risk for HCV infection compared with those who seek services in publicly funded clinics. In addition, the accuracy of self-reported risk factor information in this study was not validated, and because race/ethnicity data were not systematically collected across sites, potential differences in anti-HCV prevalence by race/ethnicity could not be analyzed. The higher overall estimated proportion of African Americans (known to have higher prevalence of anti-HCV than other race/ethnic groups) tested in the NYC clinic could explain in part the higher prevalence found in both MSM and non-MSM compared with other sites, but is unlikely to account for the consistency of findings across age strata in all sites.
Screening for risk factors (particularly injection drug use) and testing people at risk for HCV infection in STD and HIV CTS settings, where large numbers of IDUs may be seen, provides the potential for efficiently identifying HCV-infected people and providing them with referral for medical evaluation to determine their disease status and need for antiviral therapy if appropriate. In addition, identification provides infected people the opportunity to receive other needed services (e.g., hepatitis A or hepatitis B vaccine), and counseling to prevent further liver damage (e.g., avoidance of alcohol) and to keep from transmitting the infection to others.
5,21With decreasing resources to support prevention activities in publicly funded clinics, targeting HCV testing to those most likely to be infected is important. The cost of testing, both in resources and the increasing likelihood of false-positive results when testing lower-risk populations, should be weighed against the expected yield of testing. An evaluation conducted in the San Diego STD clinic showed that using recommended CDC criteria (history of injection drug use or blood transfusion before 1992) would identify 64% of clients with HCV infection while requiring testing of only 8% of clients.
8 In addition, a cost study evaluating HCV testing in STD clinics found that testing only IDUs is the most efficient, if funds are limited.
22 Although sexual transmission of HCV is possible, it appears to be inefficient, and testing MSM without a risk factor for which routine HCV testing is currently recommended is not supported by data in this report or other studies. HIV-infected people, including MSM, are an exception, and are recommended to be tested for HCV infection regardless of reported risk factors, as co-infection has important implications for progression of and therapy for both diseases.
23,24