Background

HCV incidence is increasing in the US, notably among younger people who inject drugs (PWID). In a cohort of young adult (age<30 years) PWID in San Francisco we examined whether 'injecting partner mixing' factors, i.e. age of partner and knowledge of their HCV serostatus, were associated with HCV transmission.

Methods

In 448 susceptible PWID studied prospectively. All participants were asked to report characteristics and behaviors they engaged in with up to 3 injecting partners defined as "people whom you injected the most with" in the past month". These partnerships did not specify that drugs or injecting equipment was shared. HCV incidence was estimated by age of up to 3 injecting partners, categorized as: (i) all <30; (ii) mixed-age (<&≥30); and (iii) all ≥30 years and perceived knowledge of the HCV status of participants' injecting partners' HCV status. Interaction was evaluated between partnership age categories and perceived HCV status of partners.

Results

Between 2006-2018, overall HCV incidence (/100 person years observation [pyo]) was 19.4 (95% CI: 16.4, 22.9). Incidence was highest in those with mixed-age partnerships: 28.5 (95% CI: 21.8, 37.1) and those whose partners were all <30 (23.9; 95% CI: 18.8, 30.4), and lowest if partners were ≥30 (7.5; 95% CI: 4.8, 11.8). In a multivariable analyses adjusting for age, sex (of index), injection frequency, and injection partnership 'monogamy', we found evidence for an interaction: the highest HCV incidence was seen in PWID whose partners were all <30 and who knew at least one of their partners was HCV-positive (58.9, 95% CI: 43.3, 80.0; p<0.01).

Conclusions

Younger injectors are more likely to acquire HCV from their similarly-aged peers, than older injecting partners. Protective seroadaptive behavior may contribute to reduce incidence. These findings can inform new HCV prevention approaches for young PWID needed to curb the HCV epidemic.

Importance

The population of homeless older adults is growing and experiences premature mortality. Little is known about factors associated with mortality among homeless older adults.

Objective

To identify the prevalence and factors associated with mortality in a cohort of homeless adults 50 years and older.

Design, setting, and participants

In this prospective cohort study (Health Outcomes in People Experiencing Homelessness in Older Middle Age [HOPE HOME]), 450 adults 50 years and older who were homeless at baseline were recruited via venue-based sampling in Oakland, California. Enrollment occurred in 2 phases, from July 2013 to June 2014 and from August 2017 to July 2018, and participants were interviewed at 6-month intervals.

Exposures

Baseline and time-varying characteristics, including sociodemographic factors, social support, housing status, incarceration history, chronic medical conditions, substance use, and mental health problems.

Main outcomes and measures

Mortality through December 31, 2021, based on state and local vital records information from contacts and death certificates. All-cause mortality rates were compared with those in the general population from 2014 to 2019 using age-specific standardized mortality ratios with 95% CIs.

Results

Of the 450 included participants, median (IQR) age at baseline was 58.1 (54.5-61.6) years, 107 (24%) were women, and 360 (80%) were Black. Over a median (IQR) follow-up of 55 (38-93) months, 117 (26%) participants died. Median (IQR) age at death was 64.6 (60.3-67.5) years. In multivariable analyses, characteristics associated with mortality included a first episode of homelessness at 50 years and older (adjusted hazard ratio [aHR], 1.62; 95% CI, 1.13-2.32), homelessness (aHR, 1.82; 95% CI, 1.23-2.68) or institutionalization (aHR, 6.36; 95% CI, 3.42-11.82) at any follow-up compared with being housed, fair or poor self-rated health (aHR, 1.64; 95% CI, 1.13-2.40), and diabetes (aHR, 1.55; 95% CI, 1.06-2.26). Demographic characteristics, substance use problems, and mental health problems were not independently associated. All-cause standardized mortality was 3.5 times higher (95% CI, 2.5-4.4) compared with adults in Oakland. The most common causes of death were heart disease (n = 17 [14.5%]), cancer (n = 17 [14.5%]), and drug overdose (n = 14 [12.0%]).

Conclusions and relevance

The cohort study found that premature mortality was common among homeless older adults and associated factors included late-life homelessness and ongoing homelessness. There is an urgent need for policy approaches to prevent and end homelessness among older adults in the US.

Importance

Injection drug use is the primary mode of transmission for hepatitis C virus (HCV) infection. Prior studies suggest opioid agonist therapy may reduce the incidence of HCV infection among injection drug users; however, little is known about the effects of this therapy in younger users.

Objective

To evaluate whether opioid agonist therapy was associated with a lower incidence of HCV infection in a cohort of young adult injection drug users.

Design, setting, and participants

Observational cohort study conducted from January 3, 2000, through August 21, 2013, with quarterly interviews and blood sampling. We recruited young adult (younger than 30 years) injection drug users who were negative for anti-HCV antibody and/or HCV RNA.

Exposures

Substance use treatment within the past 3 months, including non-opioid agonist forms of treatment, opioid agonist (methadone hydrochloride or buprenorphine hydrochloride) detoxification or maintenance therapy, or no treatment.

Main outcomes and measures

Incident HCV infection documented with a new positive result for HCV RNA and/or HCV antibodies. Cumulative incidence rates (95% CI) of HCV infection were calculated assuming a Poisson distribution. Cox proportional hazards regression models were fit adjusting for age, sex, race, years of injection drug use, homelessness, and incarceration.

Results

Baseline characteristics of the sample (n = 552) included median age of 23 (interquartile range, 20-26) years; 31.9% female; 73.1% white; 39.7% who did not graduate from high school; and 69.2% who were homeless. During the observation period of 680 person-years, 171 incident cases of HCV infection occurred (incidence rate, 25.1 [95% CI, 21.6-29.2] per 100 person-years). The rate ratio was significantly lower for participants who reported recent maintenance opioid agonist therapy (0.31 [95% CI, 0.14-0.65]; P = .001) but not for those who reported recent non-opioid agonist forms of treatment (0.63 [95% CI, 0.37-1.08]; P = .09) or opioid agonist detoxification (1.45 [95% CI, 0.80-2.69]; P = .23). After adjustment for other covariates, maintenance opioid agonist therapy was associated with lower relative hazards for acquiring HCV infection over time (adjusted hazard ratio, 0.39 [95% CI, 0.18-0.87]; P = .02).

Conclusions and relevance

In this cohort of young adult injection drug users, recent maintenance opioid agonist therapy was associated with a lower incidence of HCV infection. Maintenance treatment with methadone or buprenorphine for opioid use disorders may be an important strategy to prevent the spread of HCV infection among young injection drug users.

OBJECTIVE:To understand the number of young adult people who inject drugs (PWID) with hepatitis C virus (HCV) infection accessing direct-acting antiviral (DAA) treatment and their barriers and facilitators to treatment uptake. METHODS:Using prospective cohort data from young adult PWID in San Francisco with newly identified HCV infection, we calculated the number who: (i) accepted referral to DAA therapy, (ii) initiated DAA therapy, (iii) completed DAA therapy, and (iv) achieved sustained virologic response (SVR) or cure. Behavioral survey data identified possible barriers and facilitators to DAA therapy. RESULTS:Of 60 young adult PWID with new HCV infection identified between February 2015 and January 2018, thirty accepted a referral to HCV care; five initiated and completed HCV treatment and achieved cure. Barriers to DAA uptake included fear of medical establishments, competing basic needs, and delaying care because they were feeling well. CONCLUSION:While few HCV-positive young adult PWID engaged in DAA therapy, all those who did achieved cure. Youth-tailored services that overcome the stigma and marginalization related to injection drug use are needed to improve treatment uptake.

Introduction

Young injection drug users (IDU, under age 30) often inject with other IDU, creating an environment for risk of blood-borne disease transmission through sharing of needles and drug preparation equipment. Epidemiologic studies rely on self reported injection behavior data for measures of transmission risk, therefore we sought to quantify the degree of concordance of reported injecting risk behaviors between injecting dyads.

Methods

From May, 2006 through 2013 we enrolled 72 injecting dyads in San Francisco, California, who were hepatitis C virus (HCV) RNA discordant. Each partnership was followed prospectively for up to six months. Monthly interviews from each partner were date-matched and responses to relationship characteristics and risk behavior questions were compared. Concordance of reporting was estimated with the concordance correlation coefficient for longitudinal data (CCC) and the prevalence adjusted bias adjusted kappa (PABAK).

Results

Participants had a median age of 26 (IQR: 23, 28) years and median years injecting of 7.0 (IQR: 3.0, 10.6). Thirty-eight percent of the injecting dyads were also sexual partners. Concordance levels were highest for partnership characteristics, such as length of acquaintance, number of days cohabitating, and sexual intercourse in the past month (CCC=0.95; 0.82, and 0.90, respectively). Shared injection risk behaviors such as injecting with the HCV+ partner's previously used syringe and using contaminated injection preparation equipment had slight to fair agreement (CCC=0.22; 0.23; PABAK=0.43, 0.36, respectively).

Conclusions

Concordance levels ranged from low to high. Potential sources of measurement error for low agreement items include recall and social-desirability biases and question interpretation.

Housing status affects drug using behaviors, but less is known about the relationship between housing patterns and hepatitis C virus (HCV) infection. HCV-negative young people who inject drugs (PWID) were enrolled into a prospective cohort (2003-2019) with quarterly study visits. We used Cox regression to estimate the independent association of recent housing status (housed vs. unhoused, housing stability, and housing trajectory) on HCV incidence. Among 712 participants, 245 incident HCV infections occurred over 963.8 person-years (py) (cumulative incidence 24.4/100 py). An inverse relationship between time housed and HCV incidence was observed (always unhoused 45.0/100 py, 95% confidence interval (CI) 37.1, 54.5; variably housed 18.0/100 py, 95% CI 15.0, 21.3; and always housed 7.0/100 py, 95% CI 3.0, 17.3). In Cox regression models controlling for confounders, those unhoused versus housed at baseline had a 1.9-fold increased infection risk (95% CI 1.4, 2.6). Those always unhoused versus always housed had a 1.5 times greater risk of HCV (95% CI 1.0, 2.3), and those spending a portion of time in stable housing a lower risk (adjusted relative hazard 0.05, 95% CI 0.3, 0.9) with a similar trend for those being housed for less time. Young adult PWID experiencing both recent and chronic states of being unhoused are at elevated risk for HCV infection. Importantly for this group of PWID, our findings indicate that some frequency of residential housing significantly reduces HCV infection risk.

Aims

To test the value of phosphatidylethanol (PEth) as a biomarker for alcohol consumption among injecting drug users (IDUs).

Methods

As part of a longitudinal study of young IDUs, dried blood spots and self-reported alcohol by structured interview were collected at baseline. We compared self-reported alcohol use to detectable PEth (≥8 ng/ml) in the blood spots as well as the relationships between quantitative PEth results and quantity measures of alcohol consumption.

Results

There were strong associations between PEth and self-reported categorical measures of alcohol consumption (all P < 0.01). There was high specificity for reporting abstaining from alcohol; 94% of those who reported not consuming alcohol in the prior month tested negative for PEth. PEth was well correlated with measures of alcohol use (e.g. with reported number of days drinking in the prior month: Spearman r = 0.70 (P < 0.001)).

Conclusions

The positive correlation of PEth with reported alcohol consumption suggests that PEth may be a useful marker in settings where alcohol consumption is difficult to assess, or to corroborate or invalidate self-reported measures of alcohol consumption.

BACKGROUND:While HIV and unintended pregnancies are both occupational risks faced by female sex workers, the epidemiology of pregnancy and its drivers in this population remains understudied. This includes Cambodia, where the drivers of pregnancy among female entertainment and sex workers (FESW) remain unknown. The current study aimed to examine factors associated with incident pregnancy, as well as describe contraceptive use among FESW in Phnom Penh, Cambodia. METHODS:This analysis drew from the Young Women's Health Study (YWHS)-2, a 12-month observational cohort of 220 FESW aged 15-29 years, conducted between August 2009 and August 2010. Interviewer-administered questionnaires were conducted at baseline and quarterly thereafter, alongside HIV and pregnancy testing. Bivariate and multivariable extended Cox regression analysis was used to examine correlates of incident pregnancy. RESULTS:At baseline, 6.8% of participants were pregnant, and only 10.8% reported using hormonal contraceptives, with 11.3% reporting an abortion in the past 3 months. Pregnancy incidence was high, at 22/100 person-years (95% CI: 16.3-30.1). In multivariable analysis, younger age (19-24 years versus 25-29 years) (Adjusted Hazards Ratio (AHR): 2.28; 95% Confidence Interval (CI) 1.22-4.27), lower income (400,000-600,000 Riel (≤150$USD) versus > 600,000 Riel (> 150$USD)) (AHR 2.63; 95% CI 1.02-6.77) positively predicted pregnancy, while higher self-reported condom self-efficacy were associated with reduced pregnancy incidence (AHR 0.89; 95% CI 0.81-0.98). CONCLUSIONS:Results document high incidence of pregnancy and unmet reproductive health needs among FESWs in Cambodia. Findings point to an urgent need for multi-level interventions, including venue-based HIV/STI and violence prevention interventions, in the context of legal and policy reform. High pregnancy incidence in this population may also undermine recruitment and retention into HIV prevention intervention trials. The exploration of innovative and comprehensive sex worker-tailored sexual and reproductive health service models, also as part of HIV prevention intervention trials, is warranted.

Background

The current opioid epidemic across the United States has fueled a surge in the rate of new hepatitis C virus (HCV) infections among young persons who inject drugs (PWIDs). Paramount to interrupting transmission is targeting these high-risk populations and understanding the underlying network structures facilitating transmission within these communities.

Methods

Deep sequencing data were obtained for 52 participants from 32 injecting partnerships enrolled in the U-Find-Out (UFO) Partner Study, which is a prospective study of self-described injecting dyad partnerships from a large community-based study of HCV infection in young adult PWIDs from San Francisco. Phylogenetically linked transmission events were identified using traditional genetic-distance measures and viral deep sequence phylogenies reconstructed to determine the statistical support of inferences and the direction of transmission within partnerships.

Results

Using deep sequencing data, we found that 12 of 32 partnerships were genetically similar and clustered. Three additional phylogenetic clusters were found describing novel putative transmission links outside of the injecting relationship. Transmission direction was inferred correctly for 5 partnerships with the incorrect transmission direction inferred in more than 50% of cases. Notably, we observed that phylogenetic linkage was most often associated with a lower number of network partners and involvement in a sexual relationship.

Conclusions

Deep sequencing of HCV among self-described injecting partnerships demonstrates that the majority of transmission events originate from outside of the injecting partnership. Furthermore, these findings caution that phylogenetic methods may be unable to routinely infer the direction of transmission among PWIDs especially when transmission events occur in rapid succession within high-risk networks.