Assessing Consistency of Respondent-driven Sampling Estimators by Using Repeated Surveys among People Who Inject Drugs (PWID) in New Jersey.

Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the consistency of RDS estimators in real world settings. We conducted an assessment study on the consistency of RDS estimators using data from the National HIV Behavioral Surveillance - People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Population parameter estimates based on RDS-I, RDS-II, Gile's SS, and HCG were compared longitudinally and cross-sectionally. Population homophily statistics and differential recruitment statistics were estimated and compared. Convergence plots were used for RDS diagnosis. Sensitivity analyses were conducted on population size estimates and seeds biases. By comparing time-insensitive population parameters and population homophily statistics estimated by four RDS estimators, the study found that RDS-II and Gile's SS could provide longitudinally and cross-sectionally consistent estimates and population homophily statistics on gender and sexual orientation. Cross-sectional comparison of time-sensitive population parameter estimates also supported the consistency of RDS-II and Gile's SS. However, RDS-I and HCG did not perform well in those comparisons. In conclusion, RDS estimators may not address all inconsistencies, but RDS-II and Gile's SS are recommended to weight RDS samples given enough consistency was observed in them.

Assessing reliability of naïve respondent-driven sampling samples by using repeated surveys among people who inject drugs (PWID) in New Jersey.

INTRODUCTION: Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the reliability of RDS in real world settings. METHODS: We assessed the reliability of naïve RDS samples using five rounds of the National HIV Behavioral Surveillance - People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Specifically, we compared the distributions of time-insensitive demographic characteristics in temporally adjacent RDS samples with Monte Carlo Two-Sample Kolmogorov-Smirnov Test with 100,000 replicates. The distributions of time-sensitive demographic characteristics were also compared as sensitivity analyses. RESULTS: The study showed that repeated RDS samples among people who inject drugs in the greater Newark area, New Jersey were reliable in most of time-insensitive demographics and recruitment homophily statistics. Sensitivity analyses of time-sensitive demographics also presented consistencies in most of temporally adjacent samples. CONCLUSIONS: In conclusion, RDS has the potential to provide reliable samples, but demographic characteristics of RDS samples may be easily biased by homophily. Future studies using RDS may need to pay more attention to potential homophily bias and consider necessary diagnostic procedures and sample adjustments.

HIV Prevalence and Associated Factors Among Men Who have Sex with Men (MSM) in New Jersey, U.S., 2017.

This study assessed the HIV prevalence among MSM in the greater Newark New Jersey area including Essex, Hudson, Morris and Union Counties and examined correlates of HIV infection among those men. By analyzing National HIV Behavioral Surveillance data on MSM from four counties in New Jersey (N = 175), which were collected via a venue-based sampling method in 2017, this study shows that HIV prevalence among all races/ethnicities (12.5-31.9%) and all age groups (15.1-47.8%) were high. Casual sex and unprotected sex with male partners were prevalent among these men, regardless of HIV test results. MSM who were tested HIV positive were more likely to have diagnosed any sexual transmitted diseases in the last 12 months (AOR: 6.7; 95% CI 2.2, 21.3) and less likely to have had alcohol use in the past 12 months (AOR: 0.3; 95% CI 0.1, 0.8). Findings from behavioral surveillance strengthens the response to the HIV epidemic by providing policy makers and care/prevention providers with peer reviewed data to base their decisions on.

Exchange Sex Among Persons Who Inject Drugs in the New York Metropolitan Area: The Importance of Local Context, Gender and Sexual Identity.

Exchanging sex for money or drugs is known to increase risk for HIV among persons who inject drugs (PWID). To better understand determinants of exchange sex among PWID we examined factors associated with exchange sex in the New York metropolitan area-defined as New York City (NYC), NY; Newark, NJ; and Long Island, NY-using data from the 2012 National HIV Behavioral Surveillance system cycle on injection drug use. Of the 1160 PWID in this analysis, 24% reported exchange sex, with differences in gender and sexual identity by location. In multivariable analysis gay/bisexual men, heterosexual women, and lesbian, gay, or bisexual (LGB) women were more likely to exchange sex compared to heterosexual men. Exchange sex was also associated with race/ethnicity, homelessness, incarceration, location, and non-injection crack and cocaine use. We find that heterosexual women and LGB women who injected drugs residing in Newark were more likely to report exchange sex compared to NYC. This study highlights how local conditions impact exchange sex.

Using HIV surveillance data to monitor missed opportunities for linkage and engagement in HIV medical care.

Monitoring delayed entry to HIV medical care is needed because it signifies that opportunities to prevent HIV transmission and mitigate disease progression have been missed. A central question for population-level monitoring is whether to consider a person linked to care after receipt of one CD4 or VL test. Using HIV surveillance data, we explored two definitions for estimating the number of HIV-diagnosed persons not linked to HIV medical care. We used receipt of at least one CD4 or VL test (definition 1) and two or more CD4 or VL tests (definition 2) to define linkage to care within 12 months and within 42 months of HIV diagnosis. In five jurisdictions, persons diagnosed from 12/2006-12/2008 who had not died or moved away and who had zero, or less than two reported CD4 or VL tests by 7/31/2010 were considered not linked to care under definitions 1 and 2, respectively. Among 13,600 persons followed up for 19-42 months; 1,732 (13%) had no reported CD4 or VL tests; 2,332 persons (17%) had only one CD4 or VL test and 9,536 persons (70%) had two or more CD4 or VL tests. To summarize, after more than 19 months, 30% of persons diagnosed with HIV had less than two CD4 or VL tests; more than half of them were considered to have entered care if entering care is defined as having one CD4 or VL test. Defining linkage to care as a single CD4 or VL may overestimate entry into care, particularly for certain subgroups.