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1.  Is the HIV sentinel surveillance system adequate in China? Findings from an evaluation of the national HIV sentinel surveillance system 
Background
An external evaluation was conducted to assess the performance of the national HIV sentinel surveillance system (HSS), identify operational challenges at national and local levels and provide recommendations for improvement.
Methods
The United States Centers for Disease Control and Prevention’s (CDC) Updated Guidelines for Evaluating Public Health Surveillance Systems were followed to assess the key attributes of HSS. Comprehensive assessment activities were conducted, including: using a detailed checklist to review surveillance guidelines, protocols and relevant documents; conducting self-administered, anonymous surveys with 286 local China CDC staff; and carrying out field observations in 32 sentinel sites in four provinces.
Results
China has built an extensive HSS with 1888 sentinel sites to monitor HIV epidemic trends by population groups over time. The strengths of HSS lie in its flexibility, simplicity, usefulness and increase in coverage in locations and populations. With its rapid expansion in 2010, HSS faces challenges in maintaining acceptability, timeliness, data quality, representativeness and sustainability.
Recommendations
Implementation of the national guidelines should be standardized by strengthening training, monitoring and supervision of all staff involved, including community-based organizations. National surveillance guidelines need to be revised to strengthen data quality and representativeness, particularly to include specific instructions on HIV testing result provision, collection of identifying information, sample size and sampling methods particularly for men who have sex with men (MSM), collection of refusal information, and data interpretation. Sustainability of China’s HSS could be strengthened by applying locally tailored surveillance strategies, strengthening coordination and cooperation among government agencies and ensuring financial and human resources.
doi:10.5365/WPSAR.2012.3.3.004
PMCID: PMC3729100  PMID: 23908946
2.  Bridging Populations—Sexual Risk Behaviors and HIV Prevalence in Clients and Partners of Female Sex Workers, Bangkok, Thailand 2007 
The aim of this study is to estimate HIV prevalence and assess sexual behaviors in a high-risk and difficult-to-reach population of clients of female sex workers (FSWs). A modified variation of respondent-driven sampling was conducted among FSWs in Bangkok, where FSWs recruited 3 FSW peers, 1 client, and 1 nonpaying partner. After informed consent was obtained, participants completed a questionnaire, were HIV-tested, and were asked to return for results. Analyses were weighted to control for the design of the survey. Among 540 FSWs, 188 (35%) recruited 1 client, and 88 (16%) recruited 1 nonpaying partner. Clients’ median age was 38 years. HIV prevalence was 20% and was associated with younger age at first sexual experience [relative risk (RR) = 3.10, 95% confidence interval (CI) 1.16–8.24] and condom use during last sexual encounter with regular partner (RR = 3.97, 95% CI 1.09–14.61). Median age of nonpaying partners was 34 years, and HIV prevalence was 15.1%. There were 56 discordant FSW–client pairs and 14 discordant FSW–nonpaying partner pairs. Condom use was relatively high among discordant FSW–client pairs (90.1%) compared to discordant FSW–nonpaying partner pairs (18.7%). Results suggest that sexual partners of FSWs have a high HIV prevalence and can be a bridge for HIV transmission to other populations. Findings also highlight the importance of initiating surveillance and targeted programs for FSW partners, and demonstrate a recruitment method for hard-to-reach populations.
doi:10.1007/s11524-010-9542-5
PMCID: PMC3126924  PMID: 21336505
Female sex workers; Thailand; Bridge population; Male clients; HIV
3.  Evaluating respondent-driven sampling in a major metropolitan area: Comparing injection drug users in the 2005 Seattle area National HIV Behavioral Surveillance system survey with participants in the RAVEN and Kiwi Studies 
Annals of epidemiology  2010;20(2):159.
Purpose
To empirically evaluate Respondent-Driven Sampling (RDS) recruitment methods, which have been proposed as an advantageous means of surveying hidden populations.
Methods
The National HIV Behavioral Surveillance system used RDS to recruit 370 IDU in the Seattle area in 2005 (NHBS-IDU1). We compared the NHBS-IDU1 estimates of participants’ area of residence, age, race, sex and drug most frequently injected to corresponding data from two previous surveys, RAVEN and Kiwi, and to persons newly diagnosed with HIV/AIDS and reported 2001–2005.
Results
The NHBS-IDU1 population was estimated to be more likely to reside in downtown Seattle (52%) than participants in the other data sources (22%–25%), be over 50 years old (29% vs. 5%–10%) and report multiple races (12% vs. 3%–5%). The NHBS-IDU1 population resembled persons using the downtown needle exchange in age and race distribution. An examination of cross-group recruitment frequencies in NHBS-IDU1 suggested barriers to recruitment across different areas of residence, races and drugs most frequently injected.
Conclusions
The substantial differences in age and area of residence between NHBS-IDU1 and the other data sources suggest that RDS may not have accessed the full universe of Seattle area injection networks. Further empirical data is needed to guide the evaluation of RDS-generated samples.
doi:10.1016/j.annepidem.2009.10.002
PMCID: PMC2818430  PMID: 20123167
Respondent-driven sampling; injection drug users; HIV; hepatitis C
4.  Public health triangulation: approach and application to synthesizing data to understand national and local HIV epidemics 
BMC Public Health  2010;10:447.
Background
Public health triangulation is a process for reviewing, synthesising and interpreting secondary data from multiple sources that bear on the same question to make public health decisions. It can be used to understand the dynamics of HIV transmission and to measure the impact of public health programs. While traditional intervention research and metaanalysis would be ideal sources of information for public health decision making, they are infrequently available, and often decisions can be based only on surveillance and survey data.
Methods
The process involves examination of a wide variety of data sources and both biological, behavioral and program data and seeks input from stakeholders to formulate meaningful public health questions. Finally and most importantly, it uses the results to inform public health decision-making. There are 12 discrete steps in the triangulation process, which included identification and assessment of key questions, identification of data sources, refining questions, gathering data and reports, assessing the quality of those data and reports, formulating hypotheses to explain trends in the data, corroborating or refining working hypotheses, drawing conclusions, communicating results and recommendations and taking public health action.
Results
Triangulation can be limited by the quality of the original data, the potentials for ecological fallacy and "data dredging" and reproducibility of results.
Conclusions
Nonetheless, we believe that public health triangulation allows for the interpretation of data sets that cannot be analyzed using meta-analysis and can be a helpful adjunct to surveillance, to formal public health intervention research and to monitoring and evaluation, which in turn lead to improved national strategic planning and resource allocation.
doi:10.1186/1471-2458-10-447
PMCID: PMC2920890  PMID: 20670448
5.  Prevalence of Infection with Hepatitis B and C Viruses and Co-infection with HIV in Three Jails: A Case for Viral Hepatitis Prevention in Jails in the United States 
Hepatitis B vaccination and targeted testing for hepatitis C virus (HCV) are recommended for jails with medical services available. This study estimates hepatitis B virus (HBV) and HCV infection prevalence among jail inmates, since most previous studies have been conducted among prison inmates. Prison and jail populations differ: jails hold a wide spectrum of persons for an average of 10–20 days, including persons awaiting arraignment, trial, conviction, or sentencing, while prisons typically hold convicted criminals for at least 1 year. A stratified random sample of sera obtained during routine syphilis testing of inmates entering jails in Chicago (March–April 2000), Detroit (March–August 1999), and San Francisco (June 1999–December 2000) was tested for serologic markers of HBV and HCV infection. All sera had been previously tested for antibody to HIV (anti-HIV). A total of 1,292 serum samples (12% of new inmates) was tested. Antibody to HCV (anti-HCV) prevalence was 13%. Antibody to hepatitis B core antigen (anti-HBc) prevalence was 19%, and hepatitis B surface antigen (HBsAg) prevalence was 0.9%; 12% had serologic evidence of hepatitis B vaccination. Hispanics had high rates of chronic HBV infection (3.6% HBsAg positive) along with Asians (4.7% HBsAg positive). Among HIV-infected persons, 38% were anti-HCV positive and 8.2% were HBsAg positive. Anti-HBc positivity was associated with anti-HCV positivity (aOR = 4.58), anti-HIV positivity (aOR = 2.94), syphilis infection (aOR = 2.10), and previous incarceration (aOR = 1.78). Anti-HCV-positivity was associated with anti-HBc positivity (aOR = 4.44), anti-HIV-positivity (aOR = 2.51), and previous incarceration (aOR = 2.90). Jail entrants had high levels of HCV and HBV infection and HIV co-infection; HBV prevalence was comparable to previous prison studies, and HCV prevalence was lower than prison studies. Hispanics had an unexpectedly high rate of chronic hepatitis B infection and had the lowest rate of hepatitis B vaccination. The finding that hepatitis B vaccination coverage among jail entrants is lower than the general population, despite this population’s increased risk for infection, highlights the need to support vaccination in jail settings.
doi:10.1007/s11524-008-9305-8
PMCID: PMC2629523  PMID: 18622707
Viral hepatitis; Co-infections; Correctional facilities
7.  Trends in Hepatitis B Virus, Hepatitis C Virus, and Human Immunodeficiency Virus Prevalence, Risk Behaviors, and Preventive Measures among Seattle Injection Drug Users Aged 18–30 Years, 1994–2004 
Journal of Urban Health   2007;84(3):436-454.
Injection drug users (IDUs) are at risk for infection with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Information on time trends in prevalence of these viruses among IDUs and in behaviors influencing their transmission can help define the status of these epidemics and of public health efforts to control them. We conducted a secondary data analysis combining cross-sectional data from IDUs aged 18–30 years enrolled in four Seattle-area studies from 1994 to 2004. Participants in all four studies were tested for antibody to HIV (anti-HIV), hepatitis B core antigen (anti-HBc), and HCV (anti-HCV), and completed behavioral risk assessments. Logistic regression was used to investigate trends in prevalence over time after controlling for sociodemographic, drug use, and sexual behavior variables. Between 1994 and 2004, anti-HBc prevalence declined from 43 to 15% (p < 0.001), anti-HCV prevalence fell from 68 to 32% (p < 0.001) and anti-HIV prevalence remained constant at 2–3%. Declines in anti-HBc and anti-HCV prevalence were observed within the individual studies, although not all these declines were statistically significant. The declines in anti-HBc and anti-HCV prevalence remained significant after control for confounding. Although we did not observe coincident declines in injection equipment sharing practices, there were increases in self-reported needle-exchange use, condom use, and hepatitis B vaccination. We conclude that there has been a substantial and sustained reduction in prevalence rates for HBV and HCV infection among young Seattle IDUs, while HIV rates have remained low and stable.
doi:10.1007/s11524-007-9178-2
PMCID: PMC2231834  PMID: 17356901
HIV; Hepatitis B; Hepatitis C; Injection drug users; Adolescents;  Needle sharing; Needle exchange; Hepatitis B vaccination
8.  Effectiveness of Respondent-Driven Sampling for Recruiting Drug Users in New York City: Findings from a Pilot Study 
A number of sampling methods are available to recruit drug users and collect HIV risk behavior data. Respondent-driven sampling (RDS) is a modified form of chain-referral sampling with a mathematical system for weighting the sample to compensate for its not having been drawn randomly. It is predicated on the recognition that peers are better able than outreach workers and researchers to locate and recruit other members of a “hidden” population. RDS provides a means of evaluating the reliability of the data obtained and also allows inferences about the characteristics of the population from which the sample is drawn. In this paper we present findings from a pilot study conducted to assess the effectiveness of RDS to recruit a large and diversified group of drug users in New York City. Beginning with eight seeds (i.e., initial recruits) we recruited 618 drug users (injecting and non-injecting) in 13 weeks. The data document both cross-gender and cross-race and -ethnic recruitment as well as recruitment across drug-use status. Sample characteristics are similar to the characteristics of the drug users recruited in other studies conducted in New York City. The findings indicate that RDS is an effective sampling method for recruiting diversified drug users to participate in HIV-related behavioral surveys.
doi:10.1007/s11524-006-9052-7
PMCID: PMC2527186  PMID: 16739048
Human immunodeficiency virus; Recruitment of drug users; Respondent-driven sampling; Sampling hidden populations
9.  Assessment of Respondent Driven Sampling for Recruiting Female Sex Workers in Two Vietnamese Cities: Reaching the Unseen Sex Worker 
Respondent driven sampling (RDS) is a relatively new method to sample hard-to-reach populations. Until this study, female sex workers (FSWs) in Vietnam were sampled using a variety of methods, including time location sampling (TLS), which may not access the more hidden types of FSWs. This paper presents an analysis from an HIV biological and behavioral surveillance survey to assess the feasibility and effectiveness of RDS to sample FSWs, to determine if RDS can reach otherwise inaccessible FSWs in Vietnam and to compare RDS findings of HIV risk factors with a theoretical TLS. Through face-to-face interviews with FSWs in Ho Chi Minh City (HCMC) and Hai Phong (HP), data were collected about the venues where they most often solicit their clients. These data were used to create three variables to assess whether FSWs solicit their clients in locations that are visible, semi-visible and non-visible. For this analysis, the visible group simulates a sample captured using TLS. Survey results in HIV prevalence and related risk factors and service utilization, adjusted for sampling methodology, were compared across each of the three FSW visibility groups to assess potential bias in TLS relative to RDS. The number of self-reported visible FSWs (HCMC: n=311; HP: n=162) was much larger than those of the semi-visible (HCMC: n=65; HP: n=43) and non-visible (HCMC: n=37; HP: n=10) FSWs in HCMC and HP. Non-visible FSWs in both cities were just as likely as visible and semi-visible FSWs to be HIV positive (HCMC: visible 14.5%, semi-visible 13.8%, non-visible 13.5%, p value = 0.982; HP: visible 35.2%, semi-visible 30.2%, non-visible 30.0%, p value = 0.801), to practice behaviors that put them at risk for contracting and transmitting HIV (injecting drug use—HCMC: visible 13.8%, semi-visible 12.3%, non-visible 5.4%, p value = 0.347; HP: visible 38.9%, semi-visible 23.3%, non-visible 30.0%, p value = 0.378, to have no condom use in the past month —HCMC only: visible 52.7%, semi-visible 63.1%, non-visible 48.6%, p value = 0.249) and to have symptoms of a sexually transmitted infection (STI) in the past year (HCMC: visible 16.1%, semi-visible 12.3%, non-visible 16.2%, p value = 0.742; HP: visible 13.6%, semi-visible 18.6%, non-visible 20.0%, p value = 0.640). There was a difference found among the visible, semi-visible and non-visible groups in HP for no past month condom use (visible 53.1%, semi-visible 79.1%, non-visible 60.0%, p value = 0.009). This study found that RDS was successful at recruiting hidden types of FSWs in Vietnam. Past reports of FSWs in Vietnam have assessed the more visible FSWs as being the most vulnerable and at risk for HIV. Although the number of visible FSWs is much higher than those of the semi and non-visible groups, this study found that the non-visible FSWs are very vulnerable to HIV infection. If prevention programs are targeting and responding to those who are most likely to be assessed (e.g., more visible types of FSWs) then this analysis indicates that a significant proportion of the FSW population at risk for HIV may not be receiving optimal HIV information and services.
doi:10.1007/s11524-006-9099-5
PMCID: PMC1705478  PMID: 17031567
HIV; Respondent-driven sampling; Sex workers; Vietnam
11.  Assessment of Respondent Driven Sampling for Recruiting Female Sex Workers in Two Vietnamese Cities: Reaching the Unseen Sex Worker 
Respondent driven sampling (RDS) is a relatively new method to sample hard-to-reach populations. Until this study, female sex workers (FSWs) in Vietnam were sampled using a variety of methods, including time location sampling (TLS), which may not access the more hidden types of FSWs. This paper presents an analysis from an HIV biological and behavioral surveillance survey to assess the feasibility and effectiveness of RDS to sample FSWs, to determine if RDS can reach otherwise inaccessible FSWs in Vietnam and to compare RDS findings of HIV risk factors with a theoretical TLS. Through face-to-face interviews with FSWs in Ho Chi Minh City (HCMC) and Hai Phong (HP), data were collected about the venues where they most often solicit their clients. These data were used to create three variables to assess whether FSWs solicit their clients in locations that are visible, semi-visible and non-visible. For this analysis, the visible group simulates a sample captured using TLS. Survey results in HIV prevalence and related risk factors and service utilization, adjusted for sampling methodology, were compared across each of the three FSW visibility groups to assess potential bias in TLS relative to RDS. The number of self-reported visible FSWs (HCMC: n=311; HP: n=162) was much larger than those of the semi-visible (HCMC: n=65; HP: n=43) and non-visible (HCMC: n=37; HP: n=10) FSWs in HCMC and HP. Non-visible FSWs in both cities were just as likely as visible and semi-visible FSWs to be HIV positive (HCMC: visible 14.5%, semi-visible 13.8%, non-visible 13.5%, p value = 0.982; HP: visible 35.2%, semi-visible 30.2%, non-visible 30.0%, p value = 0.801), to practice behaviors that put them at risk for contracting and transmitting HIV (injecting drug use—HCMC: visible 13.8%, semi-visible 12.3%, non-visible 5.4%, p value = 0.347; HP: visible 38.9%, semi-visible 23.3%, non-visible 30.0%, p value = 0.378, to have no condom use in the past month —HCMC only: visible 52.7%, semi-visible 63.1%, non-visible 48.6%, p value = 0.249) and to have symptoms of a sexually transmitted infection (STI) in the past year (HCMC: visible 16.1%, semi-visible 12.3%, non-visible 16.2%, p value = 0.742; HP: visible 13.6%, semi-visible 18.6%, non-visible 20.0%, p value = 0.640). There was a difference found among the visible, semi-visible and non-visible groups in HP for no past month condom use (visible 53.1%, semi-visible 79.1%, non-visible 60.0%, p value = 0.009). This study found that RDS was successful at recruiting hidden types of FSWs in Vietnam. Past reports of FSWs in Vietnam have assessed the more visible FSWs as being the most vulnerable and at risk for HIV. Although the number of visible FSWs is much higher than those of the semi and non-visible groups, this study found that the non-visible FSWs are very vulnerable to HIV infection. If prevention programs are targeting and responding to those who are most likely to be assessed (e.g., more visible types of FSWs) then this analysis indicates that a significant proportion of the FSW population at risk for HIV may not be receiving optimal HIV information and services.
doi:10.1007/s11524-006-9099-5
PMCID: PMC1705478  PMID: 17031567
HIV; Respondent-driven sampling; Sex workers; Vietnam
13.  Characteristics and trends of newly identified HIV infections among incarcerated populations: CDC HIV voluntary counseling, testing, and referral system, 1992–1998 
Inmate contact with the correctional health care system provides public health professionals an opportunity to offer HIV screening to a population that might prove difficult to reach otherwise. We report on publicly funded human immunodeficiency virus (HIV) voluntary counseling, testing, and referral (VCTR) services provided to incarcerated persons in the United States. Incarcerated persons seeking VCTR services received pretest counseling and gave a blood specimen for HIV antibody testing. Specimens were considered positive if the enzyme immunoassays were repeatedly reactive and the Western blot or immunofluorescent assay was reactive. Demographics, HIV risk information, and laboratory test results were collected from each test episode. Additional counseling sessions provided more data. From 1992 to 1998, there were 527,937 records available from correctional facilities from 48 project areas; 484,277 records included a test result and 459,155 (87.0%) tests came with complete data. Overall, 3.4% (16,797) of all tests were reactive for HIV antibodies. Of reactive tests accompanied by self-reports of previous HIV test results (15,888), previous test results were 44% positive, 23% negative, 6% inconclusive or unspecified, and 27% no previous test. This indicates that 56% of positive tests were newly identified. During the study period, the number of tests per year increased three-fold. Testing increased among all racial/ethnic groups and both sexes. The largest increase was for heterosexuals who reported no other risk, followed by persons with a sex partner at risk. Overall, the greatest number of tests was reported for injection drug users (IDUs) (128,262), followed by men who have sex with men (MSM) (19,928); however, episodes for MSM doubled during the study, while for IDUs, they increased 74%. The absolute number of HIV-positive (HIV+) tests increased 50%; however, the percentage of all tests that were HIV+ decreased nearly 50% due to the increased number of tests performed. HIV+ tests fell 50% among blacks (7.6% to 3.7%), Hispanics (6.7% to 2.5%), and males (5.1% to 2.5%); 33% among females (4.5% to 3.1%); 95% among IDUs (8.6% to 4.4%); and 64% among MSM (19.3% to 11.8%). Among HIV+ episodes, those for IDUs dropped from 61.5% to 36.6%, while episodes for heterosexuals with no reported risk factor increased from 4.3% to 18.2%. The use of VCTR services by incarcerated persons rose steadily from 1992 to 1998, and 56% of HIV+ tests were newly identified. High numbers of tests that recorded risk behaviors for
doi:10.1093/jurban/78.2.241
PMCID: PMC3456357  PMID: 11419578
14.  The Potential Impact of Expanding Antiretroviral Therapy and Combination Prevention in Vietnam: Towards Elimination of HIV Transmission 
Supplemental Digital Content is Available in the Text.
Background:
Few studies have assessed the effects of antiretroviral therapy (ART) to prevent HIV transmission in Asian HIV epidemics. Vietnam has a concentrated HIV epidemic with the highest prevalence among people who inject drugs. We investigated the impact of expanded HIV testing and counseling (HTC) and early ART, combined with other prevention interventions on HIV transmission.
Methods:
A deterministic mathematical model was developed using HIV prevalence trends in Can Tho province, Vietnam. Scenarios included offering periodic HTC and immediate ART with and without targeting subpopulations and examining combined strategies with methadone maintenance therapy and condom use.
Results:
From 2011 to 2050, maintaining current interventions will incur an estimated 18,115 new HIV infections and will cost US $22.1 million (reference scenario). Annual HTC and immediate treatment, if offered to all adults, will reduce new HIV infections by 14,513 (80%) and will cost US $76.9 million. Annual HTC and immediate treatment offered only to people who inject drugs will reduce new infections by 13,578 (75%) and will cost only US $23.6 million. Annual HTC and immediate treatment for key populations, combined with scale-up of methadone maintenance therapy and condom use, will reduce new infections by 14,723 (81%) with similar costs (US $22.7 million). This combination prevention scenario will reduce the incidence to less than 1 per 100,000 in 14 years and will result in a relative cost saving after 19 years.
Conclusions:
Targeted periodic HTC and immediate ART combined with other interventions is cost-effective and could lead to potential elimination of HIV in Can Tho.
doi:10.1097/QAI.0b013e31829b535b
PMCID: PMC3814627  PMID: 23714739
antiretroviral therapy; prevention; elimination; HIV transmission; Vietnam; people who inject drugs

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