摘要：Objectives. We determined the factors associated with hepatitis C (HCV) infection among rural Appalachian drug users. Methods. This study included 394 injection drug users (IDUs) participating in a study of social networks and infectious disease risk in Appalachian Kentucky. Trained staff conducted HCV, HIV, and herpes simplex-2 virus (HSV-2) testing, and an interviewer-administered questionnaire measured self-reported risk behaviors and sociometric network characteristics. Results. The prevalence of HCV infection was 54.6% among rural IDUs. Lifetime factors independently associated with HCV infection included HSV-2, injecting for 5 or more years, posttraumatic stress disorder, injection of cocaine, and injection of prescription opioids. Recent (past-6-month) correlates of HCV infection included sharing of syringes (adjusted odds ratio = 2.24; 95% confidence interval = 1.32, 3.82) and greater levels of eigenvector centrality in the drug network. Conclusions. One factor emerged that was potentially unique to rural IDUs: the association between injection of prescription opioids and HCV infection. Therefore, preventing transition to injection, especially among prescription opioid users, may curb transmission, as will increased access to opioid maintenance treatment, novel treatments for cocaine dependence, and syringe exchange. Almost 2% of US residents have antibodies to the hepatitis C virus (HCV). Because HCV is highly transmissible parenterally, injection drug use is an efficient mechanism for virus transmission. 1 In a comprehensive meta-analysis examining HCV infection among injection drug users (IDUs), Hagan et al. 2 reported prevalence rates worldwide. Among US injection drug users, HCV prevalence among treated drug users ranged from 27% in Chicago to 92.8% in New York City. 2 An important finding was that in countries with limited resources, the prevalence was higher earlier in drug users’ injection careers, perhaps because of less access to drug treatment and harm reduction interventions such as syringe exchange. 2 Injection drug use accounts for more than 40% of incident HCV cases annually, 1 but there are other routes of transmission. These include receiving tainted blood transfusions, 1 using illicit drugs by noninjection routes and sharing drug paraphernalia (e.g., intranasal use and sharing straws or smoking and sharing crack pipes), 3,4 and sexual intercourse. 1 Risk factors for HCV infection among injectors include less education 5 and older age. 6,7 Injection-related correlates include more frequent injection, 5,6,8,9 longer injection career, 5,6,8,10,11 “backloading” (transferring drug solution from one syringe to another via removal of the plunger), 5 shooting gallery attendance, 5,12 cocaine injection, 8,10 and sharing syringes 6,9,12–14 and other injection-related paraphernalia such as filtration cottons, 13 cookers, 9,12–14 and rinse water. 9,13 These risk factors are similar to those for HIV transmission among IDUs; however, the prevalence of HCV infection is far greater than that of HIV, which has ultimately altered the course of the 2 epidemics. 15 Several studies have examined the importance of social networks in disease transmission. 16–18 Although most have focused on HIV rather than HCV infection, given the overlapping risk factors for HIV and HCV infection, parallels can be drawn. Oftentimes, individual-level risk factors do not adequately explain disease transmission, and the addition of network measures provides a much clearer picture of the potential for transmission. As noted by Borgatti, 19 measures of degree and eigenvector centrality are particularly useful when examining network diffusion and, in particular, infectious disease transmission. The previously cited work 5–14 on risk factors for HCV infection was primarily completed in urban populations; however, there are stark differences between urban areas and Appalachian Kentucky. In addition to having extreme economic distress, Appalachian Kentucky has levels of morbidity and mortality found in less developed countries. 20 In addition, little is known about injection drug use in the rural United States other than that it is becoming more prevalent with the emergence of nonmedical prescription drug use. For example, in a study conducted in Appalachia prior to the prescription drug epidemic, the prevalence of injection drug use was reported as negligible. 21 However, among a cohort of 184 rural prescription drug users interviewed in 2004 and 2005, the prevalence of injection was more than 40%. 22 Importantly, most of these IDUs were not injecting cocaine or heroin but prescription opioids such as OxyContin, which is not designed for parenteral use. 22 A more recent study comparing rural and urban drug users found that the prevalence of prescription opioid injection was significantly greater in the rural areas. 23 Preparation (e.g., crushing, dissolving) of these prescription opioids is required before injection, making the risk of HCV transmission similar for rural prescription opioid injectors as for heroin and cocaine injectors, via both infected syringes and other injection-related paraphernalia such as filtration cottons, cookers, and rinse water. Few published studies have investigated the prevalence and correlates of HCV infection among rural residents in the era of prescription drug abuse. We therefore aimed to determine the prevalence of HCV infection and both the individual and network factors associated with HCV infection among a sample of rural IDUs.
