The heterogeneous effect of short-term transfers for improving ART adherence among HIV-infected Tanzanian adults

A recently concluded randomized study in Tanzania found that short-term conditional cash and food transfers significantly improved HIV-infected patients' possession of antiretroviral therapy (ART) and reduced patient loss to follow-up (LTFU) (McCoy, S. I., Njau, P. F., Fahey, C., Kapologwe, N., Kadiyala, S., Jewell, N. P., & Padian, N. S. (2017). Cash vs. food assistance to improve adherence to antiretroviral therapy among HIV-infected adults in Tanzania. AIDS, 31(6), 815­825. doi:10.1097/QAD.0000000000001406 ). We examined whether these transfers had differential effects within population subgroups. In the parent study, 805 individuals were randomized to one of three study arms: standard-of-care (SOC) HIV services, food assistance, or cash transfer. We compared achievement of the medication possession ratio (MPR) ≥ 95% at 6 and 12 months and patient LTFU at 12 months between those receiving the SOC and those receiving food or cash (combined). Using a threshold value of p < 0.20 to signal potential effect measure modifiers (EMM), we compared intervention effects, expressed as risk differences (RD), within subgroups characterized by: sex, age, wealth, and time elapsed between HIV diagnosis and ART initiation. Short-term transfers improved 6 and 12-month MPR ≥ 95% and reduced 12-month LTFU in most subgroups. Study results revealed wealth and time elapsed between HIV diagnosis and ART initiation as potential EMMs, with greater effects for 6-month MPR ≥ 95% in the poorest patients (RD: 32, 95% CI: (9, 55)) compared to those wealthier (RD: 16, 95% CI: (5, 27); p = 0.18) and in newly diagnosed individuals (<90 days elapsed since diagnosis) (RD: 25, 95% CI: (13, 36)) compared to those with ≥90 days (RD: 0.3, 95% CI (−17, 18); p = 0.02), patterns which were sustained at 12 months. Results suggest that food and cash transfers may have stronger beneficial effects on ART adherence in the poorest patients. We also provide preliminary data suggesting that targeting interventions at patients more recently diagnosed with HIV may be worthwhile. Larger and longer-term assessments of transfer programs for the improvement of ART adherence and their potential heterogeneity by sub-population are warranted.

Rationale and design of a randomized study of short-term food and cash assistance to improve adherence to antiretroviral therapy among food insecure HIV-infected adults in Tanzania.

BACKGROUND: Food insecurity is an important barrier to retention in care and adherence to antiretroviral therapy (ART) among people living with HIV infection (PLHIV). However, there is a lack of rigorous evidence about how to improve food security and HIV-related clinical outcomes. To address this gap, this randomized trial will evaluate three delivery models for short-term food and nutrition support for food insecure PLHIV in Shinyanga, Tanzania: nutrition assessment and counseling (NAC) alone, NAC plus food assistance, and NAC plus cash transfers. METHODS/DESIGN: At three HIV care and treatment sites, 788 participants will be randomized into one of three study arms in a 3:3:1 ratio, stratified by site: NAC plus food assistance, NAC plus cash transfer, and NAC only. Eligible participants are: 1) at least 18 years of age; 2) living with HIV infection; 3) initiated ART in the past 90 days; and 4) food insecure, as measured with the Household Hunger Scale. PLHIV who are severely malnourished (body mass index (BMI) < 16 kg/m(2)) will be excluded. Participants randomized to receive food or cash transfers are eligible to receive assistance for up to six months, conditional on attending regularly scheduled visits with their HIV care provider. Participants will be followed for 12 months: the initial 6-month intervention period and then for another 6 months post-intervention. The primary outcome is ART adherence measured with the medication possession ratio. Secondary outcomes include 1) retention in care; 2) nutritional indicators including changes in food security, BMI, and weight gain; 3) viral suppression and self-reported ART adherence; and 4) participation in the labor force. DISCUSSION: This rigorously designed trial will inform policy decisions regarding supportive strategies for food insecure PLHIV in the early stages of treatment. The study will measure outcomes immediately after the period of support ends as well as 6 months later, providing information on the duration of the interventions' effect. The comparison of food to cash transfers will better inform policies favoring cash assistance or will provide rationale for the continued investment in food and nutrition interventions for PLHIV. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01957917.

Facility-based delivery in the context of Zimbabwe's HIV epidemic--missed opportunities for improving engagement with care: a community-based serosurvey.

BACKGROUND: In developing countries, facility-based delivery is recommended for maternal and neonatal health, and for prevention of mother-to-child HIV transmission (PMTCT). However, little is known about whether or not learning one's HIV status affects one's decision to deliver in a health facility. We examined this association in Zimbabwe. METHODS: We analyzed data from a 2012 cross-sectional community-based serosurvey conducted to evaluate Zimbabwe's accelerated national PMTCT program. Eligible women (≥16 years old and mothers of infants born 9-18 months before the survey) were randomly sampled from the catchment areas of 157 health facilities in five of ten provinces. Participants were interviewed about where they delivered and provided blood samples for HIV testing. RESULTS: Overall 8796 (77 %) mothers reported facility-based delivery; uptake varied by community (30-100%). The likelihood of facility-based delivery was not associated with maternal HIV status. Women who self-reported being HIV-positive before delivery were as likely to deliver in a health facility as women who were HIV-negative, irrespective of when they learned their status - before (adjusted prevalence ratio (PRa) = 1.04, 95% confidence interval (CI) = 1.00-1.09) or during pregnancy (PRa = 1.05, 95% CI = 1.01-1.09). Mothers who had not accessed antenatal care or tested for HIV were most likely to deliver outside a health facility (69%). Overall, however 77% of home deliveries occurred among women who had accessed antenatal care and were HIV-tested. CONCLUSIONS: Uptake of facility-based delivery was similar among HIV-infected and HIV-uninfected mothers, which was somewhat unexpected given the substantial technical and financial investment aimed at retaining HIV-positive women in care in Zimbabwe.

Food insecurity is a barrier to prevention of mother-to-child HIV transmission services in Zimbabwe: a cross-sectional study.

BACKGROUND: Food insecurity (FI) is the lack of physical, social, and economic access to sufficient food for dietary needs and food preferences. We examined the association between FI and women's uptake of services to prevent mother-to-child HIV transmission (MTCT) in Zimbabwe. METHODS: We analyzed cross-sectional data collected in 2012 from women living in five of ten provinces. Eligible women were ≥16 years old, biological mothers of infants born 9-18 months before the interview, and were randomly selected using multi-stage cluster sampling. Women and infants were tested for HIV and interviewed about health service utilization during pregnancy, delivery, and post-partum. We assessed FI in the past four weeks using a subset of questions from the Household Food Insecurity Access Scale and classified women as living in food secure, moderately food insecure, or severely food insecure households. RESULTS: The weighted population included 8,790 women. Completion of all key steps in the PMTCT cascade was reported by 49%, 45%, and 38% of women in food secure, moderately food insecure, and severely food insecure households, respectively (adjusted prevalence ratio (PRa) = 0.95, 95% confidence interval (CI): 0.90, 1.00 (moderate FI vs. food secure), PRa = 0.86, 95% CI: 0.79, 0.94 (severe FI vs. food secure)). Food insecurity was not associated with maternal or infant receipt of ART/ARV prophylaxis. However, in the unadjusted analysis, among HIV-exposed infants, 13.3% of those born to women who reported severe household food insecurity were HIV-infected compared to 8.2% of infants whose mothers reported food secure households (PR = 1.62, 95% CI: 1.04, 2.52). After adjustment for covariates, this association was attenuated (PRa = 1.42, 95% CI: 0.89, 2.26). There was no association between moderate food insecurity and MTCT in unadjusted or adjusted analyses (PRa = 0.68, 95% CI: 0.43, 1.08). CONCLUSIONS: Among women with a recent birth, food insecurity is inversely associated with service utilization in the PMTCT cascade and severe household food insecurity may be positively associated with MTCT. These preliminary findings support the assessment of FI in antenatal care and integrated food and nutrition programs for pregnant women to improve maternal and child health.

Social network recruitment for Yo Puedo: an innovative sexual health intervention in an underserved urban neighborhood­sample and design implications.

Most existing evidence-based sexual health interventions focus on individual-level behavior, even though there is substantial evidence that highlights the influential role of social environments in shaping adolescents' behaviors and reproductive health outcomes. We developed Yo Puedo, a combined conditional cash transfer and life skills intervention for youth to promote educational attainment, job training, and reproductive health wellness that we then evaluated for feasibility among 162 youth aged 16-21 years in a predominantly Latino community in San Francisco, CA. The intervention targeted youth's social networks and involved recruitment and randomization of small social network clusters. In this paper we describe the design of the feasibility study and report participants' baseline characteristics. Furthermore, we examined the sample and design implications of recruiting social network clusters as the unit of randomization. Baseline data provide evidence that we successfully enrolled high risk youth using a social network recruitment approach in community and school-based settings. Nearly all participants (95%) were high risk for adverse educational and reproductive health outcomes based on multiple measures of low socioeconomic status (81%) and/or reported high risk behaviors (e.g., gang affiliation, past pregnancy, recent unprotected sex, frequent substance use; 62%). We achieved variability in the study sample through heterogeneity in recruitment of the index participants, whereas the individuals within the small social networks of close friends demonstrated substantial homogeneity across sociodemographic and risk profile characteristics. Social networks recruitment was feasible and yielded a sample of high risk youth willing to enroll in a randomized study to evaluate a novel sexual health intervention.

Are hormonal contraceptive users more likely to misreport unprotected sex? Evidence from a biomarker validation study in Zimbabwe.

We analyzed biomarker validation data of unprotected sex from women in Zimbabwe to determine whether condom and sexual behavior misreporting differs between users of different contraceptive methods. Self-reported sexual behavior was compared with the presence of prostate-specific antigen (PSA) in vaginal fluid, a biomarker of semen exposure. Of the 195 women who were PSA positive, 94 (48 %) reported no sex or only condom-protected sex. Hormonal contraceptive users misreported sexual behavior less than women using non-hormonal methods (45 vs. 67 %, P = 0.03). This misclassification pattern could have implications on the elevated risk of HIV infection associated with hormonal contraception in some studies.

Food insecurity, socioeconomic status, and HIV-related risk behavior among women in farming households in Tanzania.

Food insecurity (FI) is associated with higher-risk sexual behavior in some studies. However, the overlap between FI and socioeconomic status (SES) has been poorly described. The study objectives were to: (1) determine the relationship between household FI and four dimensions of SES among sexually active Tanzanian women in farming households: expenditures, assets, flooring material of the home, and land ownership; and (2) determine whether FI is associated with higher-risk sexual behavior and relationship power. In male-headed households, FI was associated with assets, flooring material, and land ownership but not expenditures. There was no association between FI and the four dimensions of SES in female-headed households. Among women in male-headed households, but not female household heads themselves, severe FI was associated with a non-significant increase in the likelihood of being in a relationship because of material goods [adjusted prevalence ratio (PRa) = 1.76, 95 % confidence interval (CI) 0.81, 3.81] and was inversely associated with being able to ask partners to use condoms (PRa = 0.47, 95 % CI 0.25, 0.88). There was not a strong association between food security and relationship power. Our findings suggest that the association between FI and HIV risk behavior may differ depending on the type of household.

HIV treatment as prevention: considerations in the design, conduct, and analysis of cluster randomized controlled trials of combination HIV prevention.

The rigorous evaluation of the impact of combination HIV prevention packages at the population level will be critical for the future of HIV prevention. In this review, we discuss important considerations for the design and interpretation of cluster randomized controlled trials (C-RCTs) of combination prevention interventions. We focus on three large C-RCTs that will start soon and are designed to test the hypothesis that combination prevention packages, including expanded access to antiretroviral therapy, can substantially reduce HIV incidence. Using a general framework to integrate mathematical modelling analysis into the design, conduct, and analysis of C-RCTs will complement traditional statistical analyses and strengthen the evaluation of the interventions. Importantly, even with combination interventions, it may be challenging to substantially reduce HIV incidence over the 2- to 3-y duration of a C-RCT, unless interventions are scaled up rapidly and key populations are reached. Thus, we propose the innovative use of mathematical modelling to conduct interim analyses, when interim HIV incidence data are not available, to allow the ongoing trials to be modified or adapted to reduce the likelihood of inconclusive outcomes. The preplanned, interactive use of mathematical models during C-RCTs will also provide a valuable opportunity to validate and refine model projections.

HIV prevention transformed: the new prevention research agenda.

We have entered a new era in HIV prevention whereby priorities have expanded from biomedical discovery to include implementation, effectiveness, and the effect of combination prevention at the population level. However, gaps in knowledge and implementation challenges remain. In this Review we analyse trends in the rapidly changing landscape of HIV prevention, and chart a new path for HIV prevention research that focuses on the implementation of effective and efficient combination prevention strategies to turn the tide on the HIV pandemic.

Increases in human papillomavirus detection during early HIV infection among women in Zimbabwe.

BACKGROUND: Individuals who acquire human immunodeficiency virus (HIV) may experience an immediate disruption of genital tract immunity, altering the ability to mount a local and effective immune response. This study examined the impact of early HIV infection on new detection of human papillomavirus (HPV). METHODS: One hundred fifty-five Zimbabwean women with observation periods before and after HIV acquisition and 486 HIV-uninfected women were selected from a cohort study evaluating hormonal contraceptive use and risk of HIV acquisition. Study visits occurred at 3-month intervals. Cervical swab samples available from up to 6 months before, at, and up to 6 months after the visit when HIV was first detected were typed for 37 HPV genotypes or subtypes. RESULTS: We observed ∼5-fold higher odds of multiple (≥2) new HPV detections only after HIV acquisition, relative to HIV-negative women after adjusting for sexual behavior and concurrent genital tract infections. We also observed ∼2.5-fold higher odds of single new HPV detections at visits before and after HIV acquisition, relative to HIV-uninfected women in multivariable models. CONCLUSIONS: These findings suggest that HIV infection has an immediate impact on genital tract immunity, as evidenced by the high risk of multiple new HPV detections immediately after HIV acquisition.

African women recently infected with HIV-1 and HSV-2 have increased risk of acquiring Neisseria gonorrhoeae and Chlamydia trachomatis in the Methods for Improving Reproductive Health in Africa trial.

BACKGROUND: Neisseria gonorrhoeae and Chlamydia trachomatis are 2 common causative agents of cervical bacterial sexually transmitted infections (STI). Against the background of the concurrent epidemics of STIs and HIV in sub-Saharan Africa, we examined the effect of HIV-1 and HSV-2 on acquiring N. gonorrhoeae and C. trachomatis in a cohort of southern African women at risk for HIV infection. METHODS: We examined incidence of first infection with N. gonorrhoeae and C. trachomatis in the multisite randomized controlled trial Methods for Improving Reproductive Health in Africa. Multivariable Cox proportional hazards models with time-dependent covariates were used. RESULTS: The incidence rates of C. trachomatis and N. gonorrhoeae infections were 6.14 per 100 woman-years and 2.42 per 100 women-years, respectively. In multivariable analyses, women who became infected with HIV-1 were more likely to acquire C. trachomatis (adjusted hazard ratio [adj. HR], 1.86; 95% confidence interval [CI], 1.34-2.57) and N. gonorrhoeae (adj. HR, 2.29; 95% CI, 1.47-3.56) compared with HIV-uninfected women. Similarly, HSV-2 infected women were more likely to acquire C. trachomatis (adj. HR, 1.29; 95% CI, 1.05-1.58) and N. gonorrhoeae (adj. HR, 1.57; 95% CI, 1.11-2.21). Women who were of younger age, who did not live with their primary male partner, and who changed sex partners during the study were also more likely to acquire a cervical STI. CONCLUSIONS: Women recently infected with HIV-1 and HSV-2 were at increased risk of acquiring N. gonorrhoeae and C. trachomatis. Proactive screening and treatment of these common cervical infections, particularly among those infected with HIV-1 and HSV-2, should be considered for young sexually active women in settings with a high prevalence of HIV/STIs.

Impact of learning HIV status on contraceptive use in the MIRA trial.

BACKGROUND AND METHODOLOGY: We examined the effect of becoming HIV-positive on contraceptive practices in a Phase III randomised controlled trial of the diaphragm for HIV prevention. We coded self-reported contraceptive use into seven categories of methods in order of effectiveness. We compared the proportion using each category of contraception at baseline and last visit between women who did and did not become HIV-positive. We compared changes in the proportion using each category of contraception from baseline to last visit and calculated the percentage of women that moved to a more or less effective method category or stayed the same. We examined immediate and long-term changes in contraceptive use category after learning HIV-positive status. RESULTS: A total of 4645 women remained HIV-negative and 309 became HIV-positive. The proportion using each category of contraception was similar between groups at baseline and last visit. In both groups approximately one-fifth changed to a less effective method category between baseline and last visit. Few women reported using long-acting methods. Among HIV-positive women, shorter-term changes in the proportion using each category of contraception were similar to longer-term changes, though somewhat more women were using a method in the same category 3 months after seroconversion. DISCUSSION AND CONCLUSIONS: Learning about HIV-positive status did not appear to significantly change patterns of use of effective contraceptives or the probability of switching to a more or less effective method. Information about, and access to, long-acting methods should receive more attention and be a routine part of family planning programmes and prevention trials.

A comparison of four condom-use measures in predicting pregnancy, cervical STI and HIV incidence among Zimbabwean women.

OBJECTIVE: To determine which condom-use measures best predict biological outcomes in STI/HIV-prevention research. METHODS: In a prospective cohort study of 2296 HIV-negative Zimbabwean women aged 18-35 followed for up to 2 years, the authors compared four measures of condom use (use since last visit, use at last sex, frequency of use and count of unprotected acts). The authors evaluated the performance of each in predicting incidence of pregnancy, cervical STIs (chlamydia/gonorrhoea) and HIV. RESULTS: Over follow-up, 19.3% of women became pregnant, 10.3% acquired a cervical STI, and 6.9% acquired HIV infection. In multivariable analysis, all four condom-use measures were significantly associated with a reduced pregnancy incidence; statistical tests of fit suggest that the frequency of use measure was most predictive. The time to pregnancy was longer for women who, in a typical month during the previous 3 months, reported always using condoms as compared with those who never used a condom (HR 0.19; 95% CI 0.14 to 0.26). Among those women diagnosed as having prevalent chlamydia/gonorrhoea at study enrolment, three of the four reported condom-use measures were associated with a non-significant but decreased risk of incident cervical STI. Reported condom use was associated with an increased risk for cervical STI among women without chlamydia/gonorrhoea at enrolment. None of the condom-use measures were associated with HIV infection. CONCLUSIONS: The frequency of reported condom use measure best predicted pregnancy incidence; however, the authors found no evidence for a clear 'best' condom-use measure for use in STI/HIV prevention research in this population of Zimbabwean women.

Behavior change interventions to prevent HIV infection among women living in low and middle income countries: a systematic review.

We conducted a systematic review of behavioral change interventions to prevent the sexual transmission of HIV among women and girls living in low- and middle-income countries. PubMed/MEDLINE, Web of Science, the Cochrane Library, and other databases and bibliographies were systematically searched for trials using randomized or quasi-experimental designs to evaluate behavioral interventions with HIV infection as an outcome. We identified 11 analyses for inclusion reporting on eight unique interventions. Interventions varied widely in intensity, duration, and delivery as well as by target population. Only two analyses showed a significant protective effect on HIV incidence among women and only three of ten analyses that measured behavioral outcomes reduced any measure of HIV-related risk behavior. Ongoing research is needed to determine whether behavior change interventions can be incorporated as independent efficacious components in HIV prevention packages for women or simply as complements to biomedical prevention strategies.

Acceptability and use of the diaphragm and Replens lubricant gel for HIV prevention in Southern Africa.

The acceptability and use of the diaphragm and lubricant gel were assessed as part of a large randomized controlled trial to determine the effectiveness of the methods in women's HIV acquisition. 2,452 intervention-arm women were enrolled at five Southern African clinics and followed quarterly for 12-24 months. Acceptability and use data were collected by face-to-face interviews at Month 3 and Exit. Participants were "very comfortable" with the physical mechanics of diaphragm use throughout the trial, and approval of the gel consistency, quantity and the applicator was high. At Exit, consistent disclosure of use (AOR 1.97, 95% CI: 1.10-3.55); an overall high diaphragm rating (AOR 1.84, 95% CI: 1.45-2.34) and perception of partner approval (AOR 1.75, 95% CI: 1.35-2.26) were the most significant acceptability factors independently associated with consistent use. Despite being female-initiated, disclosure of use to male partners and his perceived approval of the products were factors significantly associated with their consistent use.

Financial incentives to promote retention in care and viral suppression in adults with HIV initiating antiretroviral therapy in Tanzania: a three-arm randomised controlled trial.

BACKGROUND: Financial incentives promote use of HIV services and might support adherence to the sustained antiretroviral therapy (ART) necessary for viral suppression, but few studies have assessed a biomarker of adherence or evaluated optimal implementation. We sought to determine whether varying sized financial incentives for clinic attendance effected viral suppression in patients starting ART in Tanzania. METHODS: In a three-arm, parallel-group, randomised controlled trial at four health facilities in Shinyanga region, Tanzania, adults aged 18 years or older with HIV who had started ART within the past 30 days were randomly assigned (1:1:1) using a tablet-based application (stratified by site) to receive usual care (control group) or to receive a cash incentive for monthly clinic attendance in one of two amounts: 10 000 Tanzanian Shillings (TZS; about US$4·50) or 22 500 TZS (about $10·00). There were no formal exclusion criteria. Participants were masked to the existence of two incentive sizes. Incentives were provided for up to 6 months via mobile health technology (mHealth) that linked biometric attendance monitoring to automated mobile payments. We evaluated the primary outcome of retention in care with viral suppression (<1000 copies per mL) at 6 months using logistic regression. This trial is registered with ClinicalTrials.gov, NCT03351556. FINDINGS: Between April 24 and Dec 14, 2018, 530 participants were randomly assigned to an incentive strategy (184 in the control group, 172 in the smaller incentive group, and 174 in the larger incentive group). All participants were included in the primary intention-to-treat analysis. At 6 months, approximately 134 (73%) participants in the control group remained in care and had viral suppression, compared with 143 (83%) in the smaller incentive group (risk difference [RD] 9·8, 95% CI 1·2 to 18·5) and 150 (86%) in the larger incentive group (RD 13·0, 4·5 to 21·5); we identified a positive trend between incentive size and viral suppression (p trend=0·0032), although the incentive groups did not significantly differ (RD 3·2, -4·6 to 11·0). Adverse events included seven (4%) deaths in the control group and 11 (3%) deaths in the intervention groups, none related to study participation. INTERPRETATION: Small financial incentives delivered using mHealth can improve retention in care and viral suppression in adults starting HIV treatment. Although further research should investigate the durability of effects from short-term incentives, these findings strengthen the evidence for implementing financial incentives within standard HIV care. FUNDING: National Institute of Mental Health at the US National Institutes of Health.

Biomarker validation of reports of recent sexual activity: results of a randomized controlled study in Zimbabwe.

Challenges in the accurate measurement of sexual behavior in human immunodeficiency virus (HIV) prevention research are well documented and have prompted discussion about whether valid assessments are possible. Audio computer-assisted self-interviewing (ACASI) may increase the validity of self-reported behavioral data. In 2006-2007, Zimbabwean women participated in a randomized, cross-sectional study that compared self-reports of recent vaginal sex and condom use collected through ACASI or face-to-face interviewing (FTFI) with a validated objective biomarker of recent semen exposure (prostate-specific antigen (PSA) levels). Of 910 study participants, 196 (21.5%) tested positive for PSA, an indication of semen exposure during the previous 2 days. Of these 196 participants, 23 (11.7%) reported no sex in the previous 2 days, with no difference in reported sexual activity between interview modes (12.5% ACASI vs. 10.9% FTFI; Fisher's exact test: P = 0.72). In addition, 71 PSA-positive participants (36.2%) reported condom-protected vaginal sex only; their reports also indicated no difference between interview modes (33.7% ACASI vs. 39.1% FTFI; P = 0.26). Only 52% of PSA-positive participants reported unprotected sex during the previous 2 days. Self-report was a poor predictor of recent sexual activity and condom use in this study, regardless of interview mode, providing evidence that such data should be interpreted cautiously.

Biomedical interventions to prevent HIV infection: evidence, challenges, and way forward.

Intensive research efforts for more than two decades have not yet resulted in an HIV vaccine of even moderate effectiveness. However, some progress has been made with other biomedical interventions, albeit on the basis of inconsistent levels of evidence. The male condom, if used correctly and consistently, has been proven in observational studies to be very effective in blocking HIV transmission during sexual intercourse; and, in three randomised trials, male circumcision was protective against HIV acquisition among men. Treatment of sexually transmitted infections, a public health intervention in its own right, has had mixed results, depending in part on the epidemic context in which the approach was assessed. Finally, oral and topical antiretroviral compounds are being assessed for their role in reduction of HIV transmission during sexual intercourse. Research on biomedical interventions poses formidable challenges. Difficulties with product adherence and the possibility of sexual disinhibition are important concerns. Biomedical interventions will need to be part of an integrative package that includes biomedical, behavioural, and structural interventions. Assessment of such multicomponent approaches with moderate effects is difficult. Issues to be considered include the nature of control groups and the effect of adherence on the true effectiveness of the intervention.

Sexual network structure among a household sample of urban african american adolescents in an endemic sexually transmitted infection setting.

BACKGROUND: Sexual networks play an important role in the transmission of sexually transmitted infections (STIs) and HIV. However, because of the challenges of collecting network data, relatively few empirical reports exist about the structure of sexual networks in general population samples. This study describes the structure of the sexual networks of a household sample of urban black adolescents living in an area with moderate endemic STI rates. METHODS: Random digit dialing was used to recruit a household sample of black adolescents from the Bayview-Hunter's Point neighborhood of San Francisco. Participants' recent partners and partners of partners were recruited through snowball sampling. Biologic samples were tested for current infection with gonorrhea or chlamydia. Social network analysis methods were used to describe the characteristics of the resulting sexual networks. RESULTS: One hundred and sixty-six sexually active participants were connected to 388 network members in 159 separate sexual network components. Despite relatively high prevalence of bacterial STIs (13%), components were small (3.5 people on average, and half involved only 2 people), linear and acyclic. Females were less central in their networks than males by local measures but just as central when overall structure was taken into account. CONCLUSIONS: Our results confirm, in a new setting, previous observations that sexual network structures necessary for endemic transmission of gonorrhea and chlamydia are sparsely connected.