Preplanned Studies: HIV and HCV Infection Status Among Drug Users — China, 2010−2018

The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in China remains at a low epidemic level nationwide but is highly concentrated in some regions and in some high-risk populations (1). The National HIV Sentinel Surveillance System (HSSS) was established in 1995 in China, but with changes in the HIV epidemic and increasing resources for HIV prevention and control, the development of the HSSS can be divided into 2 stages: active surveillance (1995–1998) and comprehensive surveillance (1999–present). After rapid expansion of national sentinel surveillance in 2010, this system included a nationwide surveillance network including serological and behavioral surveillance from 8 HIV-related populations. After 2010, there were 299 sentinel sites for drug users (DUs) across 30 provincial-level administrative divisions. This study was aimed to analyze serological results among the different types of DUs in HIV sentinel surveillance, for purpose of the providing information and evidence for prevention and scientific intervention to DUs.

Serial cross-sectional surveys were conducted annually among DUs from April to June. The sample size of each HSSS site was approximately 400, though if HIV prevalence within a site exceeded 10%, 250 participants were sampled. Over 60% of DUs were recruited from compulsory detoxification centers with the rest being from the community and methadone maintenance treatment (MMT) clinics. The participants in compulsory detoxification centers were recruited using consecutive sampling, and the participants from MMT clinics were required to have positive urine test results from a recent month before using consecutive sampling. When the participants were recruited from community, snowball sampling could be applied. After providing informed consent, participants completed an anonymous, structured questionnaire which included demographic information, HIV-related behaviors, and serological screening testing of HIV and hepatitis C virus (HCV) conducted by local CDC. Serological testing of HIV and HCV were conducted using the standard protocol and laboratory methods by National Center for AIDS/STD Control and Prevention (NCAIDS).

For both HIV and HCV, initial screening was done by using enzyme-linked immunosorbent assays (ELISA). If the screening result was positive, another test was required using another ELISA. Participants with 2 positive ELISA results in the surveillance system were defined antibody positive. Those who were finally confirmed positive would be referred to treatment and care in local institutions. If patients have been previously confirmed as HIV and/or HCV positive, they were not administered testing via ELISA and given the questionnaires only. Details on the criteria of HSSS have been described elsewhere (2-3). The antibody positive rates were analyzed at the national level annually from 2010 to 2018, and their trends in HIV and HCV antibody positive rates were assessed by the Linear-by-Linear Association test using SPSS software (version 18.0; IBM Corporation).

From 2010 to 2018, DUs sentinel surveillance indicated that the HIV antibody positive rate decreased from 4.5% to 2.6% (Linear-by-Linear Association ${\chi ^2}$=1,354.218, p<0.001) and that the HCV antibody positive rate decreased from 41.8% to 29.8% (Linear-by-Linear Association ${\chi ^2}$=10,220.375, p<0.001) (Figure 1). The proportion of traditional drug users (having used heroin, etc.) decreased from 79.7% in 2010 to 49.3% in 2018, and the proportion of new narcotic users (having used meth, etc.) increased from 14.9% to 42.3% with the proportion of mixed drug users (having used both of two kinds of drugs above) increasing from 5.4% to 8.4%. (Pearson ${\chi ^2}$=59,091.176, p<0.001). During 2010–2018, the HIV antibody positive rate of traditional drug users deceased from 5.4% to 4.3% (Linear-by-Linear Association ${\chi ^2}$=167.657, p<0.001), and the HIV antibody positive rate of new narcotic users fluctuated at level of 0.5% (Linear-by-Linear Association ${\chi ^2}$=0.074, p>0.5) with that of mixed drug users increasing from 1.7% to 3.1% (Linear-by-Linear Association ${\chi ^2}$=35.830, p<0.001) (Figure 2). Between 2010 and 2018, the HCV antibody positive rate of traditional drug users deceased from 47.1% to 44.1% (Linear-by-Linear Association ${\chi ^2}$=748.705, p<0.001), and the HCV antibody positive rate of new narcotic users deceased from 14.7% to 11.5% (Linear-by-Linear Association ${\chi ^2}$=240.490, p<0.001), with that of mixed drug users decreasing from 44.8% to 41.4% (Linear-by-Linear Association ${\chi ^2}$=61.704, p<0.001) (Figure 3).

Figure 1.  Trends of HIV and HCV antibody positive rates in drug user population in China, 2010–2018.

Figure 2.  Trends of HIV antibody positive rates in different drug user types in China, 2010–2018.

Figure 3.  Trends of HCV antibody positive rates in different drug user types in China, 2010–2018.