Concurrent partnerships and HIV prevalence disparities by race: linking science and public health practice

Concurrency revisited: increasing and compelling epidemiological evidence

Multiple sexual partnerships must necessarily lie at the root of a sexually transmitted epidemic. However, that overlapping or concurrent partnerships have played a pivotal role in the generalized epidemics of sub-Saharan Africa has been challenged. Much of the original proposition that concurrent partnerships play such a role focused on modelling, self-reported sexual behaviour data and ethnographic data. While each of these has definite merit, each also has had methodological limitations. Actually, more recent cross-national sexual behaviour data and improved modelling have strengthened these lines of evidence. However, heretofore the epidemiologic evidence has not been systematically brought to bear. Though assessing the epidemiologic evidence regarding concurrency has its challenges, a careful examination, especially of those studies that have assessed HIV incidence, clearly indicates a key role for concurrency.Such evidence includes: 1) the early and dramatic rise of HIV infection in generalized epidemics that can only arise from transmission through rapid sequential acute infections and thereby concurrency; 2) clear evidence from incidence studies that a major portion of transmission in the population occurs via concurrency both for concordant negative and discordant couples; 3) elevation in risk associated with partner's multiple partnering; 4) declines in HIV associated with declines in concurrency; 5) bursts and clustering of incident infections that indicate concurrency and acute infection play a key role in the propagation of epidemics; and 6) a lack of other plausible explanations, including serial monogamy and non-sexual transmission. While other factors, such as sexually transmitted infections, other infectious diseases, biological factors and HIV sub-type, likely play a role in enhancing transmission, it appears most plausible that these would amplify the role of concurrency rather than alter it. Additionally, critics of concurrency have not proposed plausible alternative explanations for why the explosive generalized epidemics occurred. Specific behaviour change messaging bringing the concepts of multiple partnering and concurrency together appears salient and valid in promoting safer individual behaviour and positive social norms.

Examining racial/ethnic disparities in sexually transmitted diseases among recent heroin-using and cocaine-using women

BACKGROUND

This study examined racial differences in the prevalence of sexual risk behaviors and their associations with sexually transmitted diseases (STDs) among recent heroin-using and cocaine-using women.

METHODS

Participants were 214 women (59% black, 41% white) who were recruited during 2002-2010 using targeted sampling to participate in a study in Baltimore, Maryland, and reported using heroin, cocaine, or crack during the previous 6 months. Participants completed self-report questionnaires about their drug use, sexual risk behaviors, and lifetime history of one of six STDs, including gonorrhea, syphilis, chlamydia, genital herpes, genital warts, or trichomoniasis.

RESULTS

More black women (50%) than white women (28%) reported a lifetime STD. Although there were no racial differences in the lifetime prevalence of sexual risk behaviors assessed, there were racial differences in the sexual behaviors associated with ever having a lifetime STD. Simple logistic regressions revealed that ever having a casual sex partner or anal sex were correlates of having a lifetime STD among black women but not among white women. Multiple logistic regression analyses revealed that ever having a casual sex partner was significantly associated with having a lifetime STD among black women, and ever trading sex for money was significantly associated with having a lifetime STD among white women.

CONCLUSIONS

Findings are consistent with national studies and elucidate racial disparities in STDs and associated sexual behaviors among recent heroin-using and cocaine-using women. Findings underscore the need to tailor STD prevention interventions differently for black and white recent heroin-using and cocaine-using women.

Change in sexual activity 12 months after ART initiation among HIV-positive Mozambicans

We assessed sexual behaviors before and 12-months after ART initiation among 277 Mozambicans attending an HIV clinic. Measured behaviors included the number of sexual partners, condom use, concurrent relationships, disclosure of HIV status, alcohol use, and partners' serostatus. Compared to before ART initiation, increases were seen 12 months after ART in the proportion of participants who were sexually active (48% vs. 64% respondents, P < 0.001) and the proportion of participants with HIV-negative or unknown serostatus partners (45% vs. 80%, P < 0.001). Almost all (96%) concurrent partnerships reported at 12 months formed after ART initiation. Although reported correct and consist condom use increased, the number of unprotected sexual relationships remained the same (n = 45). Non-disclosure of HIV-serostatus to sexual partners was the only significant predictor of practicing unprotected sex with partners of HIV-negative or unknown serostatus. Sexual activity among HIV-positive persons on ART increased 12 months after ART initiation. Ongoing secondary transmission prevention programs addressing sexual activity with multiple partners, disclosure to partners and consistent condom use with serodisconcordant partners must be incorporated throughout HIV care programs.

Concurrent sexual partnerships among men who have sex with men in Shenzhen, China

OBJECTIVES

The HIV epidemic spreads among men who have sex with men (MSM) in China. The objective of this study was to examine and compare HIV/AIDS knowledge and sexual risk for HIV between MSM who engaged in concurrent sexual partnerships and MSM who did not.

METHODS

A cross-sectional study using respondent driven sampling was conducted among 351 MSM in Shenzhen, China.

RESULTS

About half (49%) of respondents reported having concurrent sexual partnerships during the past 6 months. Among MSM with concurrent sexual partnerships, 62% had only male partners and 38% had both male and female partners. The proportion of inconsistent condom use was 42% among MSM with concurrent partners and 30% among MSM without. These 2 groups reported a similar level of self-perceived risk for HIV. Compared to MSM without concurrent sexual partners, those with such partners were more likely to work in entertainment venues and had a lower level of HIV/AIDS knowledge.

CONCLUSIONS

The large number of MSM engaging in concurrent sexual partnerships and the high prevalence of bisexuality could accelerate the spread of HIV to the general population unless effective HIV interventions for MSM are implemented in China.

HIV prevalence rates among men who have sex with men in the southern United States: population-based estimates by race/ethnicity

States across the U.S. lack effective ways to quantify HIV prevalence rates among men who have sex with men (MSM). We estimated population-based HIV prevalence rates among MSM in the 17 southern states by race/ethnicity. Through 2007, estimated HIV prevalence rates per 100,000 MSM ranged from 2,607.6 among white (non-Hispanic) MSM in Maryland to 41,512.9 among black (non-Hispanic) MSM in the District of Columbia. Black MSM rates significantly exceeded Hispanic and white MSM rates in each state. Significant racial/ethnic disparities in rates persisted in a sensitivity analysis examining the possibility that minority MSM populations had been underestimated in each state. Compared with black, Hispanic, and white non-MSM males, respectively, rates at the regional level were 25.2 times higher for black MSM, 43.0 times higher for Hispanic MSM, and 106.0 times higher for white MSM. State-level analysis of racial/ethnic-specific MSM HIV prevalence rates can help guide resource allocation and assist advocacy.

Multiple recent sexual partnerships and alcohol use among sexually transmitted infection clinic patients, Cape Town, South Africa

BACKGROUND

Multiple recent sex partners promote the rapid spread of sexually transmitted infections (STI), including human immunodeficiency virus. Alcohol use is also closely associated with unprotected sexual behavior, but its use has not been investigated in relation to multiple recent sex partners in southern Africa.

PURPOSE

To examine the combined risks of multiple recent sex partners and alcohol use among people seeking treatment for identified STI in Cape Town, South Africa.

METHODS

Men (n = 529) and women (n = 210) receiving STI clinic services completed anonymous surveys of sexual behaviors and substance use over a two-month retrospective period. Sexual risk was defined by frequencies of unprotected intercourse and drinking alcohol before sexual intercourse.

RESULTS

A total of 264 (31%) participants reported 2 or more sex partners in the previous 2 months; 87% of these partnerships occurred within 1 month of each other. Substantially greater multiple recent partners, including a greater fraction of sexual relationships estimated concurrently, were observed among men than women. Alcohol use was common in the sample, and drinking in sexual contexts was associated with multiple partners. Moderator analyses failed to show that alcohol use played a significant role in unprotected sex with multiple recent partners.

CONCLUSIONS

Multiple recent partners and drinking appear independently related to unprotected sex, and both multiple partners and alcohol use should be targeted in human immunodeficiency virus risk reduction interventions.

High HIV prevalence and diagnosis rates in New York City black men

We sought to identify population and subpopulation disparities in rates of HIV diagnosis and prevalence among black males 13 years and older in New York City. We used population-based data from the New York City HIV/AIDS surveillance registry and US Census 2000 to calculate HIV prevalence in 2006 and HIV diagnosis rates in 2007. Black males were the largest demographic group of new HIV diagnoses (n = 1,161, 33%) and persons living with HIV/AIDS in New York City (n = 24,294, 29%) and had the highest diagnosis rates (1.7 per 1,000 population) and prevalence (3.7%). Prevalence and diagnosis rates among black males were higher in higher-poverty neighborhoods than in lower-poverty neighborhoods (p < 0.01). However, very high prevalence (19.3%) was found among black males in three adjacent Manhattan neighborhoods with relatively low poverty rates, and where overall diagnosis rates among black males (7.4 per 1,000) and proportions attributable to men who have sex with men (60.0%) were high. HIV-related disparities exist not only between black males and other groups but also within black males. Success addressing the citywide HIV epidemic will be linked to success in the various portions of this highly affected, heterogeneous population.

A decade of modelling research yields considerable evidence for the importance of concurrency: a response to Sawers and Stillwaggon

In their recent article, Sawers and Stillwaggon critique the "concurrency hypothesis" on a number of grounds. In this commentary, I focus on one thread of their argument, pertaining to the evidence derived from modelling work. Their analysis focused on the foundational papers of Morris and Kretzschmar; here, I explore the research that has been conducted since then, which Sawers and Stillwaggon leave out of their review. I explain the methodological limitations that kept progress on the topic slow at first, and the various forms of methodological development that were pursued to overcome these. I then highlight recent modelling work that addresses the various limitations Sawers and Stillwaggon outline in their article. Collectively, this line of research provides considerable support for the modelling aspects of the concurrency hypothesis, and renders their critique of the literature incomplete and obsolete. It also makes clear that their call for "an end (or at least a moratorium) to research on sexual behaviour in Africa" that pertains to concurrency is unjustified.

Concurrent partnerships and HIV: an inconvenient truth

The strength of the evidence linking concurrency to HIV epidemic severity in southern and eastern Africa led the Joint United Nations Programme on HIV/AIDS and the Southern African Development Community in 2006 to conclude that high rates of concurrent sexual partnerships, combined with low rates of male circumcision and infrequent condom use, are major drivers of the AIDS epidemic in southern Africa. In a recent article in the Journal of the International AIDS Society, Larry Sawers and Eileen Stillwaggon attempt to challenge the evidence for the importance of concurrency and call for an end to research on the topic. However, their "systematic review of the evidence" is not an accurate summary of the research on concurrent partnerships and HIV, and it contains factual errors concerning the measurement and mathematical modelling of concurrency.Practical prevention-oriented research on concurrency is only just beginning. Most interventions to raise awareness about the risks of concurrency are less than two years old; few evaluations and no randomized-controlled trials of these programmes have been conducted. Determining whether these interventions can help people better assess their own risks and take steps to reduce them remains an important task for research. This kind of research is indeed the only way to obtain conclusive evidence on the role of concurrency, the programmes needed for effective prevention, the willingness of people to change behaviour, and the obstacles to change.

Racial and ethnic disparities in sexual risk behaviors and STDs during young men's transition to adulthood

CONTEXT

Racial and ethnic health disparities are an important issue in the United States. The extent to which racial and ethnic differences in STDs among youth are related to differences in socioeconomic characteristics and risky sexual behaviors requires investigation.

METHODS

Data from three waves of the National Survey of Adolescent Males (1988, 1990-1991 and 1995) were used to examine 1,880 young men's history of STDs and their patterns and trajectories of sexual risk behavior during adolescence and early adulthood. Multinomial and logistic regression analyses were conducted to test whether racial and ethnic differences in STDs are due to the lower socioeconomic status and higher levels of risky sexual behavior among minority groups.

RESULTS

Young black men reported the highest rates of sexual risk and STDs at each wave and across waves. Compared with white men, black and Latino men had higher odds of maintaining high sexual risk and increasing sexual risk over time (odds ratios, 1.7-1.9). In multivariate analyses controlling for socioeconomic characteristics, black men were more likely than white men to have a history of STDs (3.2-5.0); disparities persisted in analyses controlling for level of risky sexual behavior.

CONCLUSIONS

Race and ethnicity continue to differentiate young black and Latino men from their white peers in terms of STDs. Prevention programs that target different racial and ethnic subgroups of adolescent men and address both individual- and contextual-level factors are needed to curb STD incidence.

The reliability of sexual partnership histories: implications for the measurement of partnership concurrency during surveys

OBJECTIVES

To measure the reliability of sexual partnership histories collected during survey interviews and to assess the impact of measurement error on survey estimates of partnership concurrency.

METHODS

We used sociocentric data collected on Likoma Island (Malawi). Up to five of the respondents' most recent sexual partners were identified in population rosters. We assessed interpartner agreement (IPA) in reports of sexual partnerships (i.e. whether partners concordantly report that they have had sexual relations with each other) and its association with respondent and partnership characteristics. We estimated the extent of bias in the point prevalence of concurrency and the duration of overlap between concurrent partnerships according to two scenarios: one in which only partnerships reported by both partners were considered as 'true' ('concordant scenario'), and one in which partnerships reported by either partner were included ('complete scenario').

FINDINGS

IPA was low in nonmarital relations, but was significantly higher in ongoing than in dissolved nonmarital relations. IPA was further associated with the number of other partners the respondents or their partner(s) had, as well as with the duration of ongoing partnerships. Biases in measurements of the prevalence of concurrent partnerships were large: concurrent partnerships were rare in the concordant scenario, but common in the complete scenario. This was particularly true among never married women. Estimates of the average duration of overlap between concurrent partnerships derived from self-reported survey data were also biased, particularly among married respondents.

CONCLUSION

Future empirical tests of the 'concurrency hypothesis' and interventions targeting concurrent partnerships should take reporting biases into account.

Concurrent sexual partnerships among youth in urban Kenya: Prevalence and partnership effects

Research on concurrent sexual partnerships is hindered by lack of accurate partnership data. Using unique life-history calendar data from a population-based sample of youths aged 18-24 in urban Kenya, we estimated the prevalence and correlates of concurrency. In the sixth month before the survey, 3.5 per cent of females and 4.0 per cent of males were engaged in concurrent sexual partnerships. In the previous 9.5 years, males experienced more concurrent partnerships than females and they were of shorter duration. Using survival analysis, we find that the characteristics of initial partnerships affect entry into a second (concurrent) relationship. For females, geographic separation from a partner increases the risk of concurrency, while concurrency is positively associated with the duration of the initial relationship for males. For both sexes, the perception of partner infidelity increases the risk, suggesting that concurrency expands individuals' sexual networks and bridges additional networks involving partners' other sexual partners.

Social network characteristics and HIV sexual risk behavior among urban African American women

HIV/AIDS has emerged as a significant health threat for African American women with well-documented disparities. The purpose of this study was to assess the association between social network characteristics and high-risk sexual behaviors among a sample of urban African American women at risk of heterosexually acquired HIV/STIs. We performed a cross-sectional study of baseline data collected from the CHAT study, a randomized HIV-prevention trial targeting urban HIV-at-risk women in Baltimore, MD. Our primary outcomes were risky sexual behaviors defined as either (a) two or more sexual partners or (b) having a risky sex partner within the past 90 days. Bivariable and multivariable logistic regression examining the associations between individual and social network factors and our two outcomes of interest were conducted. The study population included 513 sexually active African American women with a mean age of 41.1 years. High levels of unemployment (89.5%), depressive symptoms (60.0%), and drug use (68.8%) were present among this high-risk urban cohort. Controlling for individual factors including participant drug use, age, and depression, having two or more sex partners within the past 90 days was associated with having a larger personal network (OR = 1.11; 95% CI, 1.06 and 1.17); more network members who pitched in to help (OR = 1.22; 95% CI, 1.04 and 1.44), provided financial support (OR = 1.33; 95% CI, 1.11 and 1.60), or used heroin or cocaine (OR = 1.26; 95% CI, 1.14 and 1.40). Having a risky sexual partner within the past 90 days was associated with having a larger social network (OR = 1.06; 95% CI, 1.00 and 1.12) and having more social networks who used heroin or cocaine (OR = 1.30; 95% CI, 1.14 and 1.49).In summary, social network characteristics are associated with HIV sexual risk behaviors among African American urban women. Social-network-based interventions that promote norms pertaining to HIV risk reduction and provide social support are needed for African American women at risk of heterosexually acquired HIV/STIs.

Empiricism and theorizing in epidemiology and social network analysis

The connection between theory and data is an iterative one. In principle, each is informed by the other: data provide the basis for theory that in turn generates the need for new information. This circularity is reflected in the notion of abduction, a concept that focuses on the space between induction (generating theory from data) and deduction (testing theory with data). Einstein, in the 1920s, placed scientific creativity in that space. In the field of social network analysis, some remarkable theory has been developed, accompanied by sophisticated tools to develop, extend, and test the theory. At the same time, important empirical data have been generated that provide insight into transmission dynamics. Unfortunately, the connection between them is often tenuous and the iterative loop is frayed. This circumstance may arise both from data deficiencies and from the ease with which data can be created by simulation. But for whatever reason, theory and empirical data often occupy different orbits. Fortunately, the relationship, while frayed, is not broken, to which several recent analyses merging theory and extant data will attest. Their further rapprochement in the field of social network analysis could provide the field with a more creative approach to experimentation and inference.

HIV among people who use drugs: a global perspective of populations at risk

This article examines the epidemiology of HIV among selected subgroups of drug users around the world who are "most at risk"--men who have sex with men, female sex workers, prisoners, and mobile populations. The underlying determinants of HIV infection among these populations include stigma, physical and sexual violence, mental illness, social marginalization, and economic vulnerability. HIV interventions must reach beyond specific risk groups and individuals to address the micro-level and macro-level determinants that shape their risk environments. Public health interventions that focus on the physical, social, and health policy environments that influence HIV risk-taking in various settings are significantly more likely to impact the incidence of HIV and other blood-borne and sexually transmitted infections across larger population groups.

Timing is everything: international variations in historical sexual partnership concurrency and HIV prevalence

BACKGROUND

Higher prevalence of concurrent partnerships is one hypothesis for the severity of the HIV epidemic in the countries of Southern Africa. But measures of the prevalence of concurrency alone do not adequately capture the impact concurrency will have on transmission dynamics. The importance of overlap duration and coital exposure are examined here.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a comparison of data from three studies of sexual behavior carried out in the early 1990s in Uganda, Thailand and the US. Using cumulative concurrency measures, the three countries appeared somewhat similar. Over 50% of both Thai and Ugandan men reported a concurrency within the last three partnerships and over 20% reported a concurrency in the last year, the corresponding rates among US men were nearly 20% for Blacks and Hispanics, and about 10% for other racial/ethnic groups. Concurrency measures that were more sensitive to overlap duration, however, showed large differences. The point prevalence of concurrency on the day of interview was over 10% among Ugandan men compared to 1% for Thai men. Ugandan concurrencies were much longer duration - a median of about two years - than either the Thai (1 day) or US concurrencies (4-9 months across all groups), and involved 5-10 times more coital risk exposure with the less frequent partner. In the US, Blacks and Hispanics reported higher prevalence, longer duration and greater coital exposure than Whites, but were lower than Ugandans on nearly every measure. Together, the differences in the prevalence, duration and coital exposure of concurrent partnerships observed align with the HIV prevalence differentials seen in these populations at the time the data were collected.

CONCLUSIONS/SIGNIFICANCE

There were substantial variations in the patterns of concurrent partnerships within and between populations. More long-term overlapping partnerships, with regular coital exposure, were found in populations with greater HIV epidemic severity.

Adaptive networks: Coevolution of disease and topology

Adaptive networks have been recently introduced in the context of disease propagation on complex networks. They account for the mutual interaction between the network topology and the states of the nodes. Until now, existing models have been analyzed using low complexity analytical formalisms, revealing nevertheless some novel dynamical features. However, current methods have failed to reproduce with accuracy the simultaneous time evolution of the disease and the underlying network topology. In the framework of the adaptive susceptible-infectious-susceptible (SIS) model of Gross [Phys. Rev. Lett. 96, 208701 (2006)]10.1103/PhysRevLett.96.208701, we introduce an improved compartmental formalism able to handle this coevolutionary task successfully. With this approach, we analyze the interplay and outcomes of both dynamical elements, process and structure, on adaptive networks featuring different degree distributions at the initial stage.

Modelling sexual transmission of HIV: testing the assumptions, validating the predictions

PURPOSE OF REVIEW

To discuss the role of mathematical models of sexual transmission of HIV: the methods used and their impact.

RECENT FINDINGS

We use mathematical modelling of 'universal test and treat' as a case study to illustrate wider issues relevant to all modelling of sexual HIV transmission.

SUMMARY

Mathematical models are used extensively in HIV epidemiology to deduce the logical conclusions arising from one or more sets of assumptions. Simple models lead to broad qualitative understanding, whereas complex models can encode more realistic assumptions and, thus, be used for predictive or operational purposes. An overreliance on model analysis in which assumptions are untested and input parameters cannot be estimated should be avoided. Simple models providing bold assertions have provided compelling arguments in recent public health policy, but may not adequately reflect the uncertainty inherent in the analysis.

Efficacy of a single-session HIV prevention intervention for black women: a group randomized controlled trial

SisterLove Inc., a community-based organization (CBO) in Atlanta, Georgia, evaluated the efficacy of its highly interactive, single-session HIV prevention intervention for black women, the Healthy Love Workshop (HLW). HLW is delivered to pre-existing groups of women (e.g., friends, sororities) in settings of their choosing. Eligible groups of women were randomly assigned to receive the intervention (15 groups; 161 women) or a comparison workshop (15 groups; 152 women). Behavioral assessments were conducted at baseline and at 3- and 6-month follow-ups. Among sexually active women at the 3-month follow-up, HLW participants were more likely than comparison participants to report having used condoms during vaginal sex with any male partner or with a primary male partner, and to have used condoms at last vaginal, anal or oral sex with any male partner. At the 6-month follow-up, HLW participants were more likely to report condom use at last vaginal, anal or oral sex with any male partner, and having an HIV test and receiving their test results. The study findings suggest that a single-session intervention delivered to pre-existing groups of black women is an efficacious approach to HIV prevention. This study also demonstrates that a CBO can develop and deliver a culturally appropriate, effective HIV prevention intervention for the population it serves and, with adequate resources and technical assistance, rigorously evaluate its intervention.

Rethinking the role of the local community in HIV epidemic spread in sub-Saharan Africa: a proximate-determinants approach

The spread of HIV in sub-Saharan Africa continues largely unabated. To improve prevention interventions, a better understanding of the determinants of HIV infection is required. Conceptual frameworks can guide epidemiological investigation and prevent a misguided focus on single risk factors in isolation. Existing frameworks of HIV infection focus on transmission. However, the transmitting individual is rarely known. By contrast, data on individual HIV acquisition are available from longitudinal studies and tests for recent HIV infection. From the perspective of individuals susceptible to HIV, it is important to distinguish between factors determining the individual's biological disposition and sexual behavior and community-level factors, which can affect both HIV acquisition and the likelihood that a sex partner chosen from a community will be infected with HIV and transmit the infection. We propose a framework that takes the susceptible individual as a starting point and links distal, proximate and biological determinants of HIV infection at both the individual and the community level. We describe three necessary ingredients for the use of the framework (identification of the relevant community, multilevel analysis and methods for causal inference).