Kathleen N. Deering

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.

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.

A generally robust approach for testing hypotheses and setting confidence intervals for effect sizes.

Standard least squares analysis of variance methods suffer from poor power under arbitrarily small departures from normality and fail to control the probability of a Type I error when standard assumptions are violated. This article describes a framework for robust estimation and testing that uses trimmed means with an approximate degrees of freedom heteroscedastic statistic for independent and correlated groups designs in order to achieve robustness to the biasing effects of nonnormality and variance heterogeneity. The authors describe a nonparametric bootstrap methodology that can provide improved Type I error control. In addition, the authors indicate how researchers can set robust confidence intervals around a robust effect size parameter estimate. In an online supplement, the authors use several examples to illustrate the application of an SAS program to implement these statistical methods.

Condom use within non-commercial partnerships of female sex workers in southern India

BackgroundAlthough female sex workers (FSWs) report high levels of condom use with commercial sex clients, particularly after targeted HIV preventive interventions have been implemented, condom use is often low with non-commercial partners. There is limited understanding regarding the factors that influence condom use with FSWs’ non-commercial partners, and of how programs can be designed to increase condom use with these partners. The main objectives of this study were therefore to describe FSWs’ self-reported non-commercial partners, along with interpersonal factors characterizing their non-commercial partnerships, and to examine the factors associated with consistent condom use (CCU) within non-commercial partnerships.MethodsThis study used data collected from cross-sectional questionnaires administered to 988 FSWs in four districts in Karnataka state in 2006-07. We used bivariate and multivariable logistic regression analysis to examine the relationship between CCU (i.e., ‘always’ compared to ‘never’, ‘sometimes’ or ‘frequently’) with non-commercial partners of FSWs (including the respondents’ husband or main cohabiting partner [if not married] and their most recent non-paying partner [who is neither a husband nor the main cohabiting partner, and with whom the FSW had sex within the previous year]) and interpersonal factors describing these partnerships, as well as social and environmental factors. Weighting and survey methods were used to account for the cluster sampling design.ResultsOverall, 511 (51.8%) FSWs reported having a husband or cohabiting partner and 247 (23.7%) reported having a non-paying partner. CCU with these partners was low (22.6% and 40.3% respectively). In multivariable analysis, the odds of CCU with FSWs’ husband or cohabiting partner were 1.8-fold higher for FSWs whose partner knew she was a sex worker (adjusted odds ratio [AOR]: 1.84, 95% confidence intervals[CI]: 1.02-3.32) and almost 6-fold higher if the FSW was unmarried (AOR: 5.73, 95%CI: 2.79-11.76]. CCU with FSWs’ non-paying partner decreased by 18% for each one-year increase in the duration of the relationship (AOR: 0.82, 95%CI: 0.68-0.97).ConclusionsThis study revealed important patterns and interpersonal determinants of condom use within non-commercial partnerships of FSWs. Integrated structural and community-driven HIV/STI prevention programs that focus on gender and reduce sex work stigma should be investigated to increase condom use in non-commercial partnerships.

Piloting a peer-driven intervention model to increase access and adherence to antiretroviral therapy and HIV care among street-entrenched HIV-positive women in Vancouver.

A peer-driven intervention (PDI) was developed to support uptake and adherence to highly active antiretroviral therapy (HAART) among women sex workers who use illicit substances in Vancouver, because uptake and adherence continues to be suboptimal. Trends of adherence were examined among women in this program by (1) exposure to the intervention and (2) risk behaviors including drug use and unstable housing. Between January 2007 and January 2008, 20 HIV-positive women were enrolled into the PDI on a rolling basis. PDI participation included weekly peer support meetings, a health advocate (buddy) system, peer outreach service, and onsite nursing care. Adherence was measured directly with pharmacy records (PR) and indirectly with self-report and viral load (VL) outcomes. Participants attended an average of 50 (21-70) PDI meetings. Overall self-reported adherence was high (92%) and most women (11) reported increased adherence from the first to the last 13 PDI meetings attended (average increase = 18%). The number of viral load tests <or=50 copies/mL increased by 40% from the pre-PDI period (1 year before enrollment), to the PDI period (duration enrolled). PR adherence and improvements in VL outcomes were higher among participants with greater housing instability and frequency of injecting/smoking drugs. Despite a very difficult environment to provide HIV care, there is evidence to suggest that the PDI may have had a positive impact on adherence outcomes. Although this would not predict long-term treatment success, the PDI approach to HIV treatment support is a promising program for women who might otherwise be excluded from treatment altogether.

To what extent is the HIV epidemic in southern India driven by commercial sex? A modelling analysis.

Background:In south India, general population HIV prevalence estimates range from 0.5 to 3%. To focus HIV prevention efforts, it is important to understand whether HIV transmission is driven by commercial sex. Methods:A dynamic HIV/sexually transmitted infection transmission model was parameterized using data from Belgaum and Mysore in south India. Fits to sexually transmitted infection/HIV data from female sex workers (FSWs) and their clients for each district were obtained. Model HIV/herpes simplex virus-2 (HSV-2) prevalence projections for the general population were cross-validated against empirical estimates not used to fit model. The model estimated the proportion of incident HIV/HSV-2 infections due to HIV/HSV-2 transmission between FSWs/clients, their noncommercial partners and other low-risk partnerships. The relative impact of a generic intervention targeting different partnerships was explored. Results:The models general population HIV/HSV-2 prevalence projections agreed well with empirical estimates. Recent increases in condom use resulted in decreasing HIV epidemics in both settings. For men, most incident HIV/HSV-2 infections (>90%) directly result from commercial sex, whereas for women most are due to bridging infections from clients of FSWs (80–90%) with the remainder mainly due to commercial sex. Less than 1.5% of incident infections are due to low-risk partnerships. Intervention impact is maximized through targeting commercial sex but substantial impact could also be achieved through targeting noncommercial partners of clients. Discussion:In southern India, HIV transmission could be driven by FSWs and their clients. While efforts to reduce HIV transmission due to commercial sex must continue, prevention programmes should also consider strategies to prevent transmission from clients to their noncommercial partners.

A dose-response relationship between exposure to a large-scale HIV preventive intervention and consistent condom use with different sexual partners of female sex workers in southern India

BackgroundThe Avahan Initiative, a large-scale HIV preventive intervention targeted to high-risk populations including female sex workers (FSWs), was initiated in 2003 in six high-prevalence states in India, including Karnataka. This study assessed if intervention exposure was associated with condom use with FSWs’ sexual partners, including a dose-response relationship.MethodsData were from a cross-sectional study (2006-07) of 775 FSWs in three districts in Karnataka. Survey methods accounted for the complex cluster sampling design. Bivariate and multivariable logistic regression was used to separately model the relationships between each of five intervention exposure variables and five outcomes for consistent condom use (CCU= always versus frequently/sometimes/never) with different sex partners, including with: all clients; occasional clients; most recent repeat client; most recent non-paying partner; and the husband or cohabiting partner. Linear tests for trends were conducted for three continuous intervention exposure variables.ResultsFSWs reported highest CCU with all clients (81.7%); CCU was lowest with FSWs’ husband or cohabiting partner (9.6%). In multivariable analysis, the odds of CCU with all clients and with occasional clients were 6.3-fold [95% confidence intervals, CIs: 2.8-14.5] and 2.3-fold [95% CIs: 1.4-4.1] higher among FSWs contacted by intervention staff and 4.9-fold [95% CIs: 2.6-9.3] and 2.3-fold [95% CIs: 1.3-4.1] higher among those who ever observed a condom demonstration by staff, respectively, compared to those who had not. A significant dose-response relationship existed between each of these CCU outcomes and increased duration since first contacted by staff (P=0.001; P=0.006) and numbers of condom demonstrations witnessed (P=0.004; P=0.026); a dose-response relationship was also observed between condom use with all clients and number of times contacted by staff (P=0.047). Intervention exposure was not associated with higher odds of CCU with the most recent repeat client, most recent non-paying partner or with the husband or cohabiting partner.ConclusionStudy findings suggest that exposure to a large-scale HIV intervention for FSWs was associated with increased CCU with commercial clients. Moreover, there were dose-response relationships between CCU with clients and increased duration since first contacted by staff, times contacted by staff and number of condom demonstrations. Additional program effort is required to increase condom use with non-commercial partners.

Evaluating large-scale HIV prevention interventions: study design for an integrated mathematical modelling approach

Background: There is an urgent need to evaluate HIV prevention interventions, thereby improving our understanding of what works, under what circumstances and what is cost effective. Objectives: To describe an integrated mathematical evaluation framework designed to assess the population-level impact of large-scale HIV interventions and applied in the context of Avahan, the Indian AIDS Initiative, in southern India. The Avahan Initiative is a large-scale HIV prevention intervention, funded by the Bill & Melinda Gates Foundation, which targets high-risk groups in selected districts of the six states most affected by the HIV/AIDS epidemic (Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh, Nagaland and Manipur) and along the national highways. Methods: One important component of the monitoring and evaluation of Avahan relies on an integrated mathematical framework that combines empirical biological and behavioural data from different subpopulations in the intervention areas, with the use of tailor-made transmission dynamics models embedded within a Bayesian framework. Results: An overview of the Avahan Initiative and the objectives of the monitoring and evaluation of the intervention is given. The rationale for choosing this evaluation design compared with other possible designs is presented, and the different components of the evaluation framework are described and its advantages and challenges are discussed, with illustrated examples. Conclusions: This is the first time such an approach has been applied on such a large scale. Lessons learnt from the CHARME project could help in the design of future evaluations of large-scale interventions in other settings, whereas the results of the evaluation will be of programmatic and public health relevance.

HIV infection among female sex workers in concentrated and high prevalence epidemics: why a structural determinants framework is needed.

Purpose of reviewThis article reviews the current state of the epidemiological literature on female sex work and HIV from the past 18 months. We offer a conceptual framework for structural HIV determinants and sex work that unpacks intersecting structural, interpersonal, and individual biological and behavioural factors. Recent findingsOur review suggests that despite the heavy HIV burden among female sex workers (FSWs) globally, data on the structural determinants shaping HIV transmission dynamics have only begun to emerge. Emerging research suggests that factors operating at macrostructural (e.g., migration, stigma, criminalized laws), community organization (e.g., empowerment) and work environment levels (e.g., violence, policing, access to condoms HIV testing, HAART) act dynamically with interpersonal (e.g., dyad factors, sexual networks) and individual biological and behavioural factors to confer risks or protections for HIV transmission in female sex work. SummaryFuture research should be guided by a Structural HIV Determinants Framework to better elucidate the complex and iterative effects of structural determinants with interpersonal and individual biological and behavioural factors on HIV transmission pathways among FSWs, and meet critical gaps in optimal access to HIV prevention, treatment, and care for FSWs globally.