Kate Shannon

Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study

BACKGROUND Results of cohort studies and mathematical models have suggested that increased coverage with highly active antiretroviral therapy (HAART) could reduce HIV transmission. We aimed to estimate the association between plasma HIV-1 viral load, HAART coverage, and number of new cases of HIV in the population of a Canadian province. METHODS We undertook a population-based study of HAART coverage and HIV transmission in British Columbia, Canada. Data for number of HIV tests done and new HIV diagnoses were obtained from the British Columbia Centre for Disease Control. Data for viral load, CD4 cell count, and HAART use were extracted from the British Columbia Centre for Excellence in HIV/AIDS population-based registries. We modelled trends of new HIV-positive tests and number of individuals on HAART using generalised additive models. Poisson log-linear regression models were used to estimate the association between new HIV diagnoses and viral load, year, and number of individuals on HAART. FINDINGS Between 1996 and 2009, the number of individuals actively receiving HAART increased from 837 to 5413 (547% increase; p=0.002), and the number of new HIV diagnoses fell from 702 to 338 per year (52% decrease; p=0.001). The overall correlation between number of individuals on HAART and number of individuals newly testing positive for HIV per year was -0.89 (p<0.0001). For every 100 additional individuals on HAART, the number of new HIV cases decreased by a factor of 0.97 (95% CI 0.96-0.98), and per 1 log(10) decrease in viral load, the number of new HIV cases decreased by a factor of 0.86 (0.75-0.98). INTERPRETATION We have shown a strong population-level association between increasing HAART coverage, decreased viral load, and decreased number of new HIV diagnoses per year. Our results support the proposed secondary benefit of HAART used within existing medical guidelines to reduce HIV transmission. FUNDING Ministry of Health Services and Ministry of Healthy Living and Sport, Province of British Columbia; US National Institute on Drug Abuse; US National Institutes of Health; Canadian Institutes of Health Research.

Global epidemiology of HIV among female sex workers: influence of structural determinants

Female sex workers (FSWs) bear a disproportionately large burden of HIV infection worldwide. Despite decades of research and programme activity, the epidemiology of HIV and the role that structural determinants have in mitigating or potentiating HIV epidemics and access to care for FSWs is poorly understood. We reviewed available published data for HIV prevalence and incidence, condom use, and structural determinants among this group. Only 87 (43%) of 204 unique studies reviewed explicitly examined structural determinants of HIV. Most studies were from Asia, with few from areas with a heavy burden of HIV such as sub-Saharan Africa, Russia, and eastern Europe. To further explore the potential effect of structural determinants on the course of epidemics, we used a deterministic transmission model to simulate potential HIV infections averted through structural changes in regions with concentrated and generalised epidemics, and high HIV prevalence among FSWs. This modelling suggested that elimination of sexual violence alone could avert 17% of HIV infections in Kenya (95% uncertainty interval [UI] 1-31) and 20% in Canada (95% UI 3-39) through its immediate and sustained effect on non-condom use) among FSWs and their clients in the next decade. In Kenya, scaling up of access to antiretroviral therapy among FSWs and their clients to meet WHO eligibility of a CD4 cell count of less than 500 cells per μL could avert 34% (95% UI 25-42) of infections and even modest coverage of sex worker-led outreach could avert 20% (95% UI 8-36) of infections in the next decade. Decriminalisation of sex work would have the greatest effect on the course of HIV epidemics across all settings, averting 33-46% of HIV infections in the next decade. Multipronged structural and community-led interventions are crucial to increase access to prevention and treatment and to promote human rights for FSWs worldwide.

Prevalence and structural correlates of gender based violence among a prospective cohort of female sex workers.

Objective To examine the prevalence and structural correlates of gender based violence against female sex workers in an environment of criminalised prostitution. Design Prospective observational study. Setting Vancouver, Canada during 2006-8. Participants Female sex workers 14 years of age or older (inclusive of transgender women) who used illicit drugs (excluding marijuana) and engaged in street level sex work. Main outcome measure Self reported gender based violence. Results Of 267 female sex workers invited to participate, 251 women returned to the study office and consented to participate (response rate of 94%). Analyses were based on 237 female sex workers who completed a baseline visit and at least one follow-up visit. Of these 237 female sex workers, 57% experienced gender based violence over an 18 month follow-up period. In multivariate models adjusted for individual and interpersonal risk practices, the following structural factors were independently correlated with violence against female sex workers: homelessness (adjusted odds ratio for physical violence (aORphysicalviolence) 2.14, 95% confidence interval 1.34 to 3.43; adjusted odds ratio for rape (aORrape) 1.73, 1.09 to 3.12); inability to access drug treatment (adjusted odds ratio for client violence (aORclientviolence) 2.13, 1.26 to 3.62; aORphysicalviolence 1.96, 1.03 to 3.43); servicing clients in cars or public spaces (aORclientviolence 1.50, 1.08 to 2.57); prior assault by police (aORclientviolence 3.45, 1.98 to 6.02; aORrape 2.61, 1.32 to 5.16); confiscation of drug use paraphernalia by police without arrest (aORphysicalviolence 1.50, 1.02 to 2.41); and moving working areas away from main streets owing to policing (aORclientviolence 2.13, 1.26 to 3.62). Conclusions Our results demonstrate an alarming prevalence of gender based violence against female sex workers. The structural factors of criminalisation, homelessness, and poor availability of drug treatment independently correlated with gender based violence against street based female sex workers. Socio-legal policy reforms, improved access to housing and drug treatment, and scale up of violence prevention efforts, including police-sex worker partnerships, will be crucial to stemming violence against female sex workers.

Mapping violence and policing as an environmental-structural barrier to health service and syringe availability among substance-using women in street-level sex work

BACKGROUND Within street-based sex work and substance-using populations, there is growing evidence to support the role of place, both physical setting and social meanings attached to place, in mediating the effectiveness and reach of health and harm reduction services. METHODS Social mapping was used to explore how health service and syringe availability may be impacted at the geographic level by avoidance of physical settings due to violence and policing among women in street-level sex work. Through a community-based research partnership and extensive peer-led outreach over a 6-month period, women were invited to participate in interview-questionnaires and mapping of their community, working conditions, and access to resources. Results were compiled used ArcGIS software and GIS street maps. In secondary analysis, logistic regression was used to model the geographic association (using likelihood ratio and significance at p<0.05) and stratified models were run to assess differential patterns of avoidance based on age, ethnicity and drug use. RESULTS The findings reveal a significant geographic relationship between a heavily concentrated core area of health and syringe availability and avoidance of physical settings due to violence and policing by 198 women in street-level sex work in Vancouver, Canada. Of particular concern, this correlation is significantly elevated among younger and Aboriginal women, active injection drug users, and daily crack cocaine smokers, suggesting significant environmental-structural barriers to interventions among these vulnerable populations. CONCLUSIONS The resultant displacement of sex work to primarily industrial settings and side streets pushes women further from health and social supports and reduces access to safer injection and drug use paraphernalia. This study offers important evidence for environmental-structural level prevention and safer environment interventions, supported by legal reforms, that facilitate safer sex work environments, including spatial programming, peer-based prevention, outreach and mobile resources, and peer-supervised safer sex work settings.

Expansion of HAART coverage is associated with sustained decreases in HIV/AIDS morbidity, mortality and HIV transmission: the "HIV Treatment as Prevention" experience in a Canadian setting.

Background There has been renewed call for the global expansion of highly active antiretroviral therapy (HAART) under the framework of HIV treatment as prevention (TasP). However, population-level sustainability of this strategy has not been characterized. Methods We used population-level longitudinal data from province-wide registries including plasma viral load, CD4 count, drug resistance, HAART use, HIV diagnoses, AIDS incidence, and HIV-related mortality. We fitted two Poisson regression models over the study period, to relate estimated HIV incidence and the number of individuals on HAART and the percentage of virologically suppressed individuals. Results HAART coverage, median pre-HAART CD4 count, and HAART adherence increased over time and were associated with increasing virological suppression and decreasing drug resistance. AIDS incidence decreased from 6.9 to 1.4 per 100,000 population (80% decrease, p = 0.0330) and HIV-related mortality decreased from 6.5 to 1.3 per 100,000 population (80% decrease, p = 0.0115). New HIV diagnoses declined from 702 to 238 cases (66% decrease; p = 0.0004) with a consequent estimated decline in HIV incident cases from 632 to 368 cases per year (42% decrease; p = 0.0003). Finally, our models suggested that for each increase of 100 individuals on HAART, the estimated HIV incidence decreased 1.2% and for every 1% increase in the number of individuals suppressed on HAART, the estimated HIV incidence also decreased by 1%. Conclusions Our results show that HAART expansion between 1996 and 2012 in BC was associated with a sustained and profound population-level decrease in morbidity, mortality and HIV transmission. Our findings support the long-term effectiveness and sustainability of HIV treatment as prevention within an adequately resourced environment with no financial barriers to diagnosis, medical care or antiretroviral drugs. The 2013 Consolidated World Health Organization Antiretroviral Therapy Guidelines offer a unique opportunity to further evaluate TasP in other settings, particularly within generalized epidemics, and resource-limited setting, as advocated by UNAIDS.

Violence, Condom Negotiation, and HIV/STI Risk Among Sex Workers

This article focuses on the link between violence against sex workers and condom use which is key to understanding why some sex worker populations are particularly vulnerable to elevated rates of HIV/STI infection compared with the general population.

A Systematic Review of the Correlates of Violence Against Sex Workers

We conducted a systematic review in June 2012 (updated September 2013) to examine the prevalence and factors shaping sexual or physical violence against sex workers globally. We identified 1536 (update = 340) unique articles. We included 28 studies, with 14 more contributing to violence prevalence estimates. Lifetime prevalence of any or combined workplace violence ranged from 45% to 75% and over the past year, 32% to 55%. Growing research links contextual factors with violence against sex workers, alongside known interpersonal and individual risks. This high burden of violence against sex workers globally and large gaps in epidemiological data support the need for research and structural interventions to better document and respond to the contextual factors shaping this violence. Measurement and methodological innovation, in partnership with sex work communities, are critical.

Occupational stigma as a primary barrier to health care for street-based sex workers in Canada

Individuals working in the sex industry continue to experience many negative health outcomes. As such, disentangling the factors shaping poor health access remains a critical public health priority. Within a quasi-criminalised prostitution environment, this study aimed to evaluate the prevalence of occupational stigma associated with sex work and its relationship to barriers to accessing health services. Analyses draw on baseline questionnaire data from a community-based cohort of women in street-based sex work in Vancouver, Canada (2006–2008). Of a total of 252 women, 141 (55.9%) reported occupational sex work stigma (defined as hiding occupational sex work status from family, friends and/or home community), while 125 (49.6%) reported barriers to accessing health services in the previous six months. In multivariable analysis, adjusting for sociodemographic, interpersonal and work environment risks, occupational sex work stigma remained independently associated with an elevated likelihood of experiencing barriers to health access. Study findings indicate the critical need for policy and societal shifts in views of sex work as a legitimate occupation, combined with improved access to innovative, accessible and non-judgmental health care delivery models for street-based sex workers that include the direct involvement of sex workers in development and implementation.

Potential community and public health impacts of medically supervised safer smoking facilities for crack cocaine users.

There is growing evidence of the public health and community harms associated with crack cocaine smoking, particularly the risk of blood-borne transmission through non-parenteral routes. In response, community advocates and policy makers in Vancouver, Canada are calling for an exemption from Health Canada to pilot a medically supervised safer smoking facility (SSF) for non-injection drug users (NIDU). Current reluctance on the part of health authorities is likely due to the lack of existing evidence surrounding the extent of related harm and potential uptake of such a facility among NIDUs in this setting. In November 2004, a feasibility study was conducted among 437 crack cocaine smokers. Univariate analyses were conducted to determine associations with willingness to use a SSF and logistic regression was used to adjust for potentially confounding variables (p < 0.05). Variables found to be independently associated with willingness to use a SSF included recent injection drug use (OR = 1.72, 95% CI: 1.09–2.70), having equipment confiscated or broken by police (OR = 1.96, 95% CI: 1.24–2.85), crack bingeing (OR = 2.16, 95% CI: 1.39–3.12), smoking crack in public places (OR = 2.48, 95% CI: 1.65–3.27), borrowing crack pipes (OR = 2.50, 95% CI: 1.86–3.40), and burns/ inhaled brillo due to rushing smoke in public places (OR = 4.37, 95% CI: 2.71–8.64). The results suggest a strong potential for a SSF to reduce the health related harms and address concerns of public order and open drug use among crack cocaine smokers should a facility be implemented in this setting.

Community-based HIV prevention research among substance-using women in survival sex work: The Maka Project Partnership

Substance-using women who exchange sex for money, drugs or shelter as a means of basic subsistence (ie. survival sex) have remained largely at the periphery of HIV and harm reduction policies and services across Canadian cities. This is notwithstanding global evidence of the multiple harms faced by this population, including high rates of violence and poverty, and enhanced vulnerabilities to HIV transmission among women who smoke or inject drugs. In response, a participatory-action research project was developed in partnership with a local sex work agency to examine the HIV-related vulnerabilities, barriers to accessing care, and impact of current prevention and harm reduction strategies among women in survival sex work. This paper provides a brief background of the health and drug-related harms among substance-using women in survival sex work, and outlines the development and methodology of a community-based HIV prevention research project partnership. In doing so, we discuss some of the strengths and challenges of community-based HIV prevention research, as well as some key ethical considerations, in the context of street-level sex work in an urban setting.