bluuebunny/crossref_metadata_2025_split huggingface dataset:
O1-S08.06 Variability in the numbers and types of sex partners of female sex workers and its impact on HIV prevalence in southern India
Authors: Deering K , Shoveller J , Pickles M , Shaw S , Moses S , Blanchard J , Washington R , Ramesh B M , Isac S , Boily M C 
Published: July 2011

BackgroundHeterogeneity in the structure of sex work within and across female sex worker (FSW) populations may be an important determinant of the spread of HIV. We characterised heterogeneity in sexual structure and assessed how it influenced HIV prevalence on a population level in southern India.MethodsWe used data collected from FSWs and clients in three districts (A, B, C) in Karnataka state, India, as part of the Avahan AIDS Initiative, a large-scale targeted HIV prevention program. A deterministic model of HIV transmission among FSWs/clients was parameterised/fitted to the district (A) with the highest FSW/client HIV prevalence in 2005 (33.9%/6.2%). We conducted multiple sensitivity analyses to examine how sexual structure parameters (Abstract O1-S08.06 figure 1) influenced modelled HIV prevalence within district A and identified sources of heterogeneity that could explain differences in HIV prevalence between district A and districts B and C.Abstract O1-S08.06 Figure 1Impact of varying each sexual structure parameter through a wide range (half to double the baseline value) on peak HIV prevalence in district A.1.1Red bars=a positive correlation and grey bars=a negative correlation. Bars are arranged in the order of the absolute impact of each parameter on peak HIV prevalence.ResultsDuration of sex work (2.6-fold), duration of the repeat client/FSW relationship (1.7-fold) and numbers of clients of FSWs (1.6-fold) exhibited the largest differences across districts. In district A, doubling the numbers of clients of FSWs, numbers of visits to FSWs by clients and frequency of sex acts with repeat clients increased HIV prevalence the most. Interestingly, doubling the duration of the repeat FSW-client relationship and fraction of repeat clients decreased HIV prevalence the most (Abstract O1-S08.06 figure 1). The observed differences in the mean numbers of clients per month between districts (A:56; B:46; C:34) could alone explain most of the lower HIV prevalence in districts B and C relative to district A. Relative to that observed in district A, the lower number of sex acts with repeat clients in district B and larger FSW population size in district C could also explain these districts' lower HIV prevalence.ConclusionsThe impact of each sexual structure parameter on HIV prevalence depended on the values of other parameters, since many parameters were correlated to keep the total number of FSW-client/client-FSW partnerships equal. Although the rules defining how parameters need to be empirically validated, results demonstrate how their definition were of critical importance in influencing outcomes. The heterogeneous risk faced by FSWs needs to be recognised to explain differences in HIV prevalence, and to inform population-specific interventions capable of addressing the complexities implied by this heterogeneity.
O1-S09.01 Increased condom use and decreased HIV & STI prevalence among female sex workers following a targeted HIV prevention program in Karnataka, South India
Authors: Moses S , Ramesh B M , Isac S , Reza-Paul S , Alary M , Bradley J , Washington R , Beattie T , Blanchard J 
Published: July 2011

BackgroundWe assessed the impact of a large-scale, targeted HIV prevention program among female sex workers (FSWs) in Karnataka state, south India.MethodsIn the context of an HIV prevention program involving 18 districts, funded by the Bill & Melinda Gates Foundation, we conducted initial (R1) and two follow-up (R2 and R3) survey rounds (integrated behavioural and biological assessments), involving random samples of urban FSWs in three selected districts. The total urban FSW population size of the three districts is estimated at 8600. Initial surveys were conducted at 7–19 months following program commencement in 2004–2005, and each follow-up survey at two to three year intervals thereafter. Multivariable logistic regression models were used, with weights to account for a complex sampling design. Results presented are for the three districts combined.Results1242 FSWs participated in R1, 1238 in R2 and 1248 in R3. In R3, 98% and 92% of FSWs reported contact by a peer educator and having visited a project STI clinic, respectively. HIV prevalence declined steadily from R1 to R3, and in R3 compared to R1, there were reductions in HIV prevalence (24.8% vs 13.3%, adjusted OR (AOR)=0.59, 95% CI 0.41% to 0.86%, p=0.005); active syphilis (12.7% vs 8.8%, AOR=0.44, 95% CI 0.31% to 0.61%, p<0.001); and high-titre syphilis (6.6% vs 3.2%, AOR=0.33, 95% CI 0.21% to 0.51%, p<0.001). Trichomoniasis (Tv), chlamydial infection (Ct) and gonorrhoea (Ng) were assessed in one district in R3. From R1 to R3, Tv declined from 32.9% to 3.5% (AOR=0.07, 95% CI 0.04% to 0.15%, p<0.001); Ng from 5.4% to 0.9% (AOR 0.22, 95% CI 0.0.07% to 0.71%, p=0.01); and Ct from 10.8% to 4.6% (AOR 0.38, 95% CI 0.19% to 0.75%, p=0.006). Comparing R3 with R1 in all three districts, reported condom use at last sex increased significantly for repeat clients (60.1% to 93.9, AOR 11.2, 95% CI 7.2% to 17.5%, p<0.001); for occasional clients (81.0% to 88.2%, AOR 2.8, 95% CI 1.9% to 4.1%, p<0.001); and for regular (non-commercial) partners (24.4% to 55.9%, AOR 5.0, 95% CI 2.4% to 10.3%, p<0.001). Condom use overall was strongly associated with level of peer educator contact, having been exposed to condom demonstrations, and attendance at a program health clinic.ConclusionsOver 6 years, this large-scale HIV prevention program for FSWs achieved high rates of program coverage, high rates of condom use with clients, and significant reductions in HIV and STI prevalence. It will be important to sustain these efforts in the long term.
O1-S01.05 Estimating the rate of annual chlamydia screening uptake in US women
Authors: Heijne J , Althaus C , Herzog S , Tao G , Kent C , Low N 
Published: July 2011

BackgroundAnnual chlamydia testing of all sexually active women aged 25 years and under followed by a repeated test 3 months after treatment is recommended by the US Centers for Disease Control and Prevention (CDC) guidelines. Data from the Healthcare Effectiveness Data and Information Set (HEDIS) estimate chlamydia test coverage at about 40% per year in the last 5 years. We used empirical data and mathematical models to determine whether observed patterns of chlamydia testing are consistent with CDC guidelines and with actual trends in chlamydia prevalence in US women aged 15–25 years.MethodsFirst, published data from women enrolled in commercial health plans from 2002 to 2006 (n=1 985 920) were used to estimate the annual chlamydia testing rate in women aged 15–25. Second, trends in chlamydia prevalence in the same age group were studied using data from 1999/2000 to 2007/2008 (n∼600 each round) from the US National Health and Nutrition Examination Survey (NHANES). We used a Susceptible-Infected-Recovered-Susceptible (SIRS) model to estimate the annual screening rate that fit the chlamydia prevalence data best. The model described a closed population with behavioural parameters reflecting people aged 15–25 years. It explicitly incorporated sexual partnerships and took into account re-infection. Finally, the model was used to examine the effect of repeated chlamydia testing 3 months after treatment on chlamydia prevalence and to calculate repeat infection rates.ResultsThe estimated rate at which women are tested for chlamydia ranges from 0.06 to 0.11 per year, which corresponds to a chlamydia test every 9 to 16 years on average and an annual coverage of roughly 10%. We found no statistical evidence that chlamydia prevalence changed between 1999 and 2008 in sexually active women aged 15–25 years taking part in NHANES. Predictions from the model of the impact of screening at a rate of 0.11 per year were consistent with the observed stable chlamydia prevalence. Repeat chlamydia testing 3 months after treatment at the estimated screening level hardly influenced population prevalence. The percentage of women with a repeat infection was highest 3.8 months after treatment.ConclusionOur study demonstrates the challenges of implementing chlamydia screening. This study suggests that low rates of chlamydia testing in the US have not reduced population chlamydia prevalence substantially.
O1-S09.02 HIV elimination without antiretroviral therapy (ART) in Southern India: modelling and projected costs
Authors: Pickles M , Vickerman P , Vassall A , Ramesh BM , Deering K , Chandrashekar S , Isac S , Moses S , Alary M , Boily M C 
Published: July 2011

BackgroundThere is widespread interest in the use of antiretroviral therapy for eliminating HIV. However, it is possible that bringing other existing interventions to scale, such as condom promotion among female sex workers (FSWs) could reduce HIV transmission to low levels in some settings. Avahan, the Indian AIDS Initiative, has attained high coverage among FSWs in southern India, achieved large increases in condom use (>90% use condoms consistently), and substantial reductions (35–60% relative decreases over 5 years) in FSW HIV prevalence have been observed in the three districts with three rounds of FSW surveys. This modelling analysis projects the long-term impact of the Avahan intervention strategy in these districts.MethodsA bespoke dynamical model of HIV transmission among FSW/clients was parameterised and fitted to district specific behavioural and STI/HIV prevalence data within a Bayesian framework. The model fits for each district were used to determine whether the long-term impact of the current level of condom use achieved through Avahan, will reduce the HIV incidence among FSWs and clients to less than 1 infection per 1000 FSWs and clients per year (elimination definition used by Granich, Lancet 2009). The probability of local elimination, time till elimination, and costs (extended from detailed costing for first 3 years in 2008 US$) and HIV infections averted of achieving this was estimated.ResultsWith the current high level of condom use in all 3 districts, the probability that the HIV incidence among FSWs and clients becoming <1 infection per 1000 by 2050 is >95%. The Abstract O1-S09.02 figure 1 suggests local elimination is likely to occur earlier in Bellary (median: 2023) than in Mysore (2028) and Belgaum (2030), with the required intervention duration being 11–35 years. The discounted cost of achieving local elimination in each of the settings is estimated to be $8-11 000 000 with 5000–11 000 HIV infections averted up to 2050.Abstract O1-S09.02 Figure 1Posterior distribution of the year when HIV indicates in FSWs and clients goes below 1 infection per 1000 FSWs and clients.ConclusionOur results suggest Avahan could result in local elimination of HIV among FSWs and clients in these districts without ART. Current discussions around the use of ART for HIV elimination should also consider other prevention strategies, especially in concentrated epidemic settings where eliminating HIV from FSWs and clients is likely to eliminate HIV in the general population. Our modest estimated costs for local elimination could be completely offset against averted ART costs.
O1-S09.03 Main results and impact analysis of annual Chlamydia screening in a large register-based programme in the Netherlands
Authors: van den Broek I V F , van Bergen J A N E A M , Fennema H S A , Götz H M , Hoebe C J P A , Over E , van der Sande M A B , Schmid B V , Op de Coul E L M 
Published: July 2011

BackgroundChlamydia screening programmes can only work when they motivate sufficient persons at risk to get tested regularly. The outcomes of the Chlamydia Screening Implementation (CSI) in the Netherlands are novel and valuable because of the large scale of the programme (315 000 young persons targeted), its systematic nature (invitations based on municipal registers) and its multiple screening rounds (annual invitations in three consecutive years).MethodsFrom April 2008 to March 2010, Chlamydia Screening was offered annually to municipal-registered 16–29 year olds in three regions of the Netherlands. A phased implementation was applied by grouping clusters in three random, risk-stratified blocks. Participation and positivity rates were compared between blocks submitted to 1, 2 or 3 screening rounds (3rd round only partially completed). The effect of the repeated screening rounds on the prevalence of Chlamydia in the whole target group was estimated by weighting procedures comparing demographic characteristics of participants and target group.ResultsThe participation rate in the first round was 16% among all invitees and 20% among the sexually active target population (M13%, F 25%). The participation fell down to 11% in blocks invited two times and 9% in the block invited three times, whereas it was 13% in the control block invited in round two only. The positivity rate in round one was 4.2% among all participants. Positivity rates decreased significantly to 4.0% in blocks screened twice and to 3.5% in the block screened thrice (p=0.04); in the control block 4.3% tested positive. The population prevalence was estimated at 2.6% in Amsterdam, 3.8% in Rotterdam and 2.4% in South Limburg. The prevalence declined over the three screening rounds, but declines were not significant (see Abstract O1-S09.03 figure 1).Abstract O1-S09.03 Figure 1Estimated Chlamydia prevalence among young people invited for Chlamydia screening 1, 2 or 3 times at annual intervals, as compared to a control group invited only once. [*bars indicate high-low estimates for South Limburg, an adaptation to correct for participant selection.ConclusionsThe participation in the CSI project was lower than expected and declined with repeated invitation. Chlamydia positivity rates were reduced by 17% in clusters screened three times, whereas these stayed high in control groups. Only a small and non-significant impact on population prevalence was measured. Further extrapolation of the findings in a simulation model suggest a limited impact on Chlamydia prevalence after 10 years of screening and estimates of cost-effectiveness do not support a nationwide roll-out of this programme in the Netherlands.
O1-S09.04 Modelled impact of changing participation rates on effectiveness of population based chlamydia screening
Authors: Schmid B V , van den Broek I V F , Op de Coul E L M , van Bergen J E A M , Fennema J S A , Götz H M , Hoebe C J P A , Kretzschmar M 
Published: July 2011

BackgroundThe Chlamydia Screening Implementation (CSI) is a Dutch large-scale pilot of an internet-based self-sampling Chlamydia trachomatis (Ct) screening program for 16–29-year-old men and women. The effectiveness of CSI can be estimated from changes in the positivity rate of the sampled individuals, but shifts in health-care use and CSI participation rates makes modelling a valuable alternative approach for estimating screening effectiveness.MethodsWe simulated the spread of Ct in a heterosexual population of age 13–65, using sexual survey data to parametrise a dynamic sexual contact network. A screening program was implemented in the model by constructing “participation trees”, which capture the likelihood to participate given an individuals participation history, as observed in the CSI program. Currently available health-care options to test for and treat Ct were also implemented in the model as a baseline (including trends in their usage), against which the effect of screening could be compared. In order to estimate the long-term effects of screening on the Ct prevalence in the Netherlands, future participation rates were estimated from trends in the yearly number of new participants, and by extrapolation of the participation trees.ResultsCompared to a baseline scenario, there is a moderate additional effect of 3 years of screening: the estimated Ct prevalence for the target population (16–29) dropped from 2.8% to 1.7% in large cities, and from 1.9% to 1.2% in more rural regions. As repeated invitees were likely not to participate, the largest effect of screening occurred in its first year when everyone in the target population was invited for the first time. After 3 years, the largest effect of screening on the Ct prevalence had been reached. Due to the anticipated further decrease in participation rates the long-term decrease in Ct prevalence is estimated to be in the range of 0.5–0.7 and 0.4–0.6 per cent-points in urban and rural regions, respectively.ConclusionsA continued population based screening program has a permanent additional effect on lowering the Ct prevalence in the Netherlands, but the size of this effect is strongly tied to the participation rate in the targeted population. Therefore, the accuracy of long-term predictions of screening effectiveness depends on a good model implementation of the available data on participation behaviour.
O1-S10.02 HIV and bacterial STI testing among men who have sex with men in the USA
Authors: Rosenberger J G , Van Der Pol B , Herbenick D , Novak D S , Reece M , Fortenberry J D 
Published: July 2011

PurposeGrowing literature has documented the extent to which bacterial sexually transmitted infections (STI) facilitate transmission/acquisition of HIV. Due to the disproportionate impact of HIV on men who have sex with men (MSM), public health messaging encourages routine STI and HIV screening among this population. This study sought to document testing behaviours among MSM in the US and understand factors associated with STI testing.MethodsData were collected via an internet survey from 27 756 18–80 year old MSM members of an online sexual networking website. Measures included sociodemographics, STI/HIV testing behaviours, STI/HIV diagnoses, and lifetime sexual behaviour history.ResultsParticipants' mean age was 39.0 years, ethnicities included white (84.5%), Latino (6.4%), African American (3.5%), and most (79.9%) identified as homosexual. Over half (54.2%) indicated they were not in a romantic relationship, and nearly all (88.9%) had been sexually active with more than one partner in the past year. Testing rates (past year) were similar for both HIV(65.4%) and STI (60.8%), yet testing in the past 6 months differed with men reporting more frequent STI testing (63.8%) compared to HIV (46.5%); rates of infection in the previous 2 years included gonorrhoea (4.5%), Chlamydia (4.1%), and HIV (3.2%), with lifetime HIV infection rate being 12.5%. Among men living with HIV infection, rates of bacterial STI testing in the past year were higher (76.1%), with gonorrhoea and Chlamydia rates being 8.6% and 7.6% respectively. Both race and sexual orientation were predictive of bacterial STI testing in the past year, with non-white and bisexual men being less likely to have done so (p<0.01).ConclusionsThese data provide a large scale assessment of HIV and STI testing among MSM in the US Findings from this study highlight gaps in screening between bacterial STI and HIV and suggest a need to promote services that offer HIV and STI testing simultaneously.
O1-S11.05 Adolescent sexual intercourse and neighbourhood social disorder
Authors: Wiehe S , Kwan M P , Hoch S , Brooks B W , Burgess A , Wilson J , Fortenberry J D 
Published: July 2011

BackgroundLittle is known about how and where an adolescent lives and spends time relates to her health-related behaviours. Social disorder, or where crime occurs, is associated with various health outcomes but few have considered its association with adolescent sexual behaviour. Our objective was to assess whether contextual exposure to social disorder is correlated with self-reported sexual intercourse among adolescent girls.Design and MethodsGirls (N=48), aged 14–16, were recruited from a single geographic urban area and monitored for 1 week using a GPS-enabled cell phone. Adolescents completed an ACASI survey on self-reported sexual intercourse in the last 30 days. In addition to recorded home and school address, phones transmitted location data every 5 min (travel points). Using ArcGIS, we defined social disorder as aggregated point-level Unified Crime Report data within a 200 metre Euclidian buffer from home and each travel point. Using Stata, we analysed how social disorder exposures differed among girls who reported having sex or not.ResultsGirls reporting sexual activity spent less time at home (30.9% vs 55.7%, p<0.001) and more time at least 5 km away from home (29.5% vs 12.4%, p=0.01). Girls who reported sex in the last 30 days lived in areas of higher social disorder than girls not reporting sex (p=0.01). There were no significant differences in exposure to social disorder based on travel data among girls reporting sex or not, however. Exposure to social disorder varied by school/non-school day as well as time of day. [Abstract O1-S11.05 figure 1].Abstract O1-S11.05 Figure 1Average 200 m crime counts by time of day/day of week and self-reported sexual intercourse in the last 30 days.ConclusionsEven within neighbourhoods, social disorder surrounding the home as defined by crime within a 1-block radius correlates with adolescent sexual intercourse behaviour. Although adolescents reporting having sex are less likely to spend time at home and more likely to be further from home than girls not reporting sex, the areas where they travel to are not different in terms of social disorder.