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Introduction Women attending termination of pregnancy (TOP) clinics are a risk group for STIs, and those with STIs are at increased risk of developing postabortal complications. We explored what STI care is provided in Dutch TOP clinics, and we compared these results with the United Kingdom (UK). Methods A qualitative study including 14 semi-structured interviews with health care professionals (HCPs) in TOP clinics (Netherlands: 9, UK: 5). Interviews were recorded, transcribed, and analysed by thematic content analysis. Results In the Netherlands, azithromycin prophylaxis is routinely prescribed after a surgical TOP, but not routinely after a medical TOP. STI tests are only offered by Dutch clinics if clients are considered at high STI risk based on the intake questionnaire. High costs of STI testing form the main barrier for clients not accepting STI testing, as costs are not covered by all health insurances. Alternatively, some clinics refer women to the Public Health Service (PHS), where STI testing is free for high-risk groups. This also involves barriers as not all women go for testing. HCPs in TOP clinics that collaborate with PHSs in the Sense program (sexual and reproductive health care) experience less barriers, as free STI testing is then offered on location of the TOP clinic. Sexual health counselling in TOP clinics is often limited to birth control conversations, also in the UK. The major difference between Dutch and UK TOP clinics is that UK clinics (who are not privately owned) offer free STI testing to all clients. Conclusion HCPs in Dutch TOP clinics consider STI testing an important part of their service, but financial barriers prevent STI testing on location. In the UK, free STI care is broadly implemented in TOP clinics. Collaboration with PHSs (in Sense program) could improve STI testing and sexual health counselling in Dutch TOP clinics. Disclosure of interest statement The study is funded by the RIVM. No pharmaceutical grants were received in the development of this study.

Introduction The proportion of MSM unaware of their HIV infection is 31% in the Netherlands. People who are unaware of HIV are more likely to transmit HIV to others and are unable to benefit from (early) treatment. To improve HIV testing, it is crucial to identify characteristics of MSM who were never tested. Methods We analysed HIV testing behaviour in the Dutch sample (n = 3,787) of the European MSM Internet Survey (EMIS) in relation to socio-demographic and behavioural factors by logistic regression. Results Of the MSM, 20.5% reported to be ‘never tested for HIV’. The adjusted model showed that MSM of younger age ( 40 yrs), with lower education (2.1 CI 1.8–2.4 vs high), with lower HIV knowledge (5.5 CI 3.8–8.0 vs higher) had higher odds on ‘never tested for HIV’. Further, MSM with lower sexual risks were more likely to be never tested for HIV; MSM with no UAI Conclusion MSM with lower sexual risks were more likely to be never tested for HIV, suggesting that MSM make risk assessments to inform their choices about HIV testing. Nevertheless, MSM who never tested for HIV also showed sexual behaviour that put them at HIV risk, and are therefore important to target for HIV interventions. Disclosure of interest statement The study is funded by the RIVM. No pharmaceutical grants were received in the development of this study.

Background The 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. Methods We 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. Results Compared 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. Conclusions A 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.

Background Chlamydia infections are frequently found in young persons and ethnic minorities. Ethnicity can be defined in different ways. In this study, ethnic disparities in Chlamydia trachomatis positivity in the Netherlands were assessed comparing two definitions of ethnicity. The study objective was to determine which definition is most useful to discriminate persons at risk for Chlamydia infection. Methods Chlamydia positivity rates in persons aged 16−29 years, were investigated using data from the first round of the Chlamydia Screening Implementation (CSI, 2008−2009) and surveillance data from specialised at STI centres in the Netherlands (2009), comparing self-defined ethnicity and ethnicity based on the country of birth of a person and his parents (first and second generation immigrants). The relation between ethnicity and Chlamydia positivity rates were evaluated using logistic regression, adjusting for age, sex and SES, in both data sets. Results Overall, the Chlamydia positivity rate was 13 % in the STI centres, and 5% in CSI. Being a young (first or second generation) immigrant was associated with Chlamydia positivity in both CSI (adjusted OR 2.3 [95% CI 2.0 to 2.6]) and the STI centres (adjusted OR 1.4 [95% CI 1.3 to 1.5]). Classifying the population by self-defined ethnicity resulted in a considerable group labelling themselves as Dutch (57% of the immigrants in CSI and 60% of those in the STI centres), especially second generation immigrants (72% in CSI and 80% in the STI centres). Self-defined non-Dutch ethnicity showed similar associations with testing positive in CSI (OR 2.4 [95% CI 2.1 to 2.7]) and the STI centres (OR 1.2 [95% CI 1.0 to 1.3]), but the model basing ethnicity on country of birth of a person and his parents had a better fit (higher likelihood). Self-defined ethnicity may allow for more personal input, this however also makes it a dynamic variable: in the second round of CSI, 15% of the immigrants identified themselves by a different ethnicity than in the first round see Abstract P1-S4.02 Figure 1. Conclusions Both self-defined ethnicity and ethnicity based on the country of birth of a person and his parents, can be used to detect young persons at a higher risk of Chlamydia infection. However the definition of ethnicity based on the country of birth explains variation in the Chlamydia data better and is objective and constant, whereas self-defined ethnicity would disregard a large part of the young population at higher risk for Chlamydia infection.

Background A register- and Internet-based chlamydia screening started in 2008 among 16–29 year olds in Amsterdam, Rotterdam and South-Limburg, aiming to reduce population prevalence of chlamydia infections. Automated respondent reminders by letter, email and SMS were used to encourage and optimise participation. The contribution of reminders on package request and sample return was examined in relation to characteristics of the target population. Methods On average, 280 000 persons were annually invited by means of a personal letter. Individuals who did not respond to the invitation letter received a reminder letter after 1 month. Email- and SMS reminders were sent to individuals who requested a test kit and did not return a sample or did not check their test results online. We evaluated the effect of reminders on response and participation rates in two screening rounds. Logistic regression analyses were conducted to identify determinants of providing a GSM number, late response (requesting a test package after a reminder letter), and late participation (returning a sample after email/SMS reminders). Results The overall package request rate in the first round increased from 12% to 20% (see Abstract P2-S8.06 Figure 1) after the reminder letter (in round 2 from 8% to 14%). The proportion of individuals returning a sample increased from 10% to 16% after email/SMS reminders (in round 2 from 7% to 11%). Of all respondents, 99% provided an email address and 72% a GSM number. Factors associated with providing a GSM number were younger age (16–24 yrs), non-Dutch background, lower educational level, symptoms of an STI, and sexual risk behaviour in the past 6 months (p Conclusions Respondents’ willingness to provide an email address or GSM number for communication during the screening procedure was high. Factors associated with providing a GSM number were also related to chlamydia positivity. Automated respondents reminders by letter influenced response rates (package request) and resulted in reaching more people at higher risk. Email- and SMS reminders contributed substantially to participation rates (sample return).

Background The impact of a Chlamydia screening programme can be measured by the incremental amount of Chlamydia tests performed and cases detected as compared to the throughput in regular care. In the Netherlands, regular STI care is provided by specialised STI-centres (aimed at high-risk groups) and General Practitioners (GP9s, basic opportunistic screening and care for symptomatic cases). An annual register-based Chlamydia screening programme is implemented in three regions since 2008. Methods The number of persons tested and cases detected in the Chlamydia Screening among 16–29 year olds in Amsterdam, Rotterdam and South Limburg, 2008–2010, were compared to consultations and diagnoses in this age group reported in surveillance data from STI centres in the regions and estimates of STI care in general practices in these regions, 2007–2010. Round 3 data are based on the first 6 months of the year. Results The baseline testing rates (at STI centers and by GP9s in year pre-screening) were 10% in Rotterdam, 13% in Amsterdam and 6% in South-Limburg. CSI increased testing rates steeply in the first year to 26–30% in the cities and 17% in Limburg; this decreased to 20–21% and 13% in round 3, still doubling testing rates as compared to baseline. Positivity rates at regular STI-care facilities are higher than in CSI: 12–15% in regular care vs 4–5% in CSI; therefore the addition of CSI to case-finding in the three regions was lower than that to testing: the screening programme added about 41% on top of the cases found in regular care in round 1, but this decreased to 20% in round 3 due to lower participation and positivity rates in consecutive rounds. Conclusions By comparison to regular testing at STI centers and in general practice, the Chlamydia Screening had a major contribution towards the number of young people tested for Chlamydia in the three regions. The addition towards case-finding was lower, because the case-detection rate of the screening programme was lower than that in regular care. The Screening programme did not seem to affect the number of patients seen in regular care, but double “consumers” cannot be excluded.

Background Reinfections remain challenging in the control of Chlamydia trachomatis (Ct). In a systematic internet-based Ct Screening programme (CSI) in the Netherlands, all Ct-positive participants automatically received a test kit after 6 months to facilitate discovery of reinfections. Determinants for reinfection for two screening rounds, treatment and partner notification are discussed. Methods CSI-home-based testkits can be requested online after register based postal invitation. Infected participants get a referral letter for their health provider to get treatment for themselves and their current partner; expartners can be alerted by the participant and request a test kit via the website. Participants fill in a questionnaire on sexual behaviour voluntarily. Ct-positives answer questions about treatment and partner notification 10 days after checking their results. Infected participants who do not check their result online receive it by postal letter. After 6 months retest kits are automatically sent to previously infected participants. Results Overall, 3185 participants (4.1%) tested positive; 7% of Ct-positives did not check their result online and received a postal letter. The majority (86%) of Ct-positive participants who answered the treatment questionnaire (response 43%) was treated within 2 weeks after checking their result online; 80% of those with a current relationship reported their partner had also been treated and 16% of those with past relationships notified ex-partners via the website. One third of the ex-partners participated, 28% of whom were Ct-positive. After 6 months, 3055 participants received a retest kit and 66% responded. The reinfection rate was 8.8%. Results of the questionnaire revealed 75% of retest-positives had been treated for the initial infection and 70% had had their partner treated, while these proportions were 87% and 80% among retest-negatives. At higher risk for reinfections were young people ( Conclusions The uptake of retesting was successful counting two third with automatically sent testkits 6 months after screening. Reinfection rates were high, especially among known risk-groups. Questionnaire results show that follow-up of (partner) treatment after Chlamydia infections could be improved.

Background Partner notification (PN) is crucial for STI control. We developed SuggestATest.nl (SAT), an internet-based notification system for verified diagnoses of STI/HIV, that uses an index-chosen method per partner (email, text messaging, postal letter or a gay dating site; anonymous or non-anonymous). SAT was piloted at the Public Health STI clinics in Amsterdam and Rotterdam, the Netherlands. It was offered additional to counselling by the nurse. Method We evaluated SAT use and effectiveness from March-July 2012. Numbers/method of sent SAT notifications were extracted from the SAT database, and epidemiological data from electronic patient records. Determinants for SAT use (age, sex, ethnicity, partners, STI) were assessed using logistic regression analysis. Results Of 1184 index-clients receiving a SAT code, 160 (14%) notified through SAT. They sent 588 notifications (median 2), 82% by text messaging and 16% by email; 86% was non-anonymous. Univariate analysis of SAT use in heterosexuals showed that people with only 1 partner used SAT less often than others; this was the only significant predictor. In MSM, the STI diagnosed was the only significant univariate factor, with MSM with syphilis using SAT more often than MSM having other STI. Among all 67 SAT users in Rotterdam, 56% (225/402) of their eligible partners were notifiable, and 95% (213/225) of those were notified using SAT. In 17 MSM, 36% (87/239) of eligible partners were notifiable, and 97 (111% of 87) were notified in SAT. Of all notified partners, 56% entered SAT to see the STI they were notified for, and 20% visited the STI clinic in Amsterdam/Rotterdam. STI positivity in partners was lower in those notified by SAT (28%, n = 116) than in those with contact cards (45%, n = 152; p Conclusion SAT is a valuable addition for supporting partner notification and management, although challenges as non-notifiable partners are not solved by SAT.

Background The number of newly diagnosed HIV infections among men who have sex with men (MSM) has gradually increased in the Netherlands during the past decade. However, the current HIV surveillance system cannot differentiate recent HIV infections from longstanding HIV infections. We determined the proportion of recent HIV infections (RI) and estimated HIV incidence using Recent Infection Testing Algorithm (RITA) among newly diagnosed HIV infections among MSM in Amsterdam and Rotterdam. Methods Plasma samples (n = 251) collected from newly HIV-diagnosed MSM during 2009–2011 at the STI clinics in Amsterdam and Rotterdam were analysed in the study. To test for recent infections, anti-HIV avidity index (AI) was measured in plasma with Architect HIV Ag/Ab Combo immunoassay. Samples were classified as recent if the AI was ≤ 0.80. Data on viral load, CD4 count and previous HIV testing were incorporated in the RITA algorithm to minimise false recent infections. HIV incidence and 95% confidence intervals (CI) were estimated using previously described methods. Results Of the 251 samples from MSM, 83 were classified as recent by the avidity index. Five cases were reclassified as non-recent based on low CD4 count (n = 2) and viral load (n = 2) and history of HIV infection (n = 1) and thus, 78/251 (31%) infections were determined as recent on RITA. Proportions of RIs in 2009, 2010 and 2011 were 32%, 28% and 33%, respectively. The estimate for combined incidence was 1.5% per year (95% CI 1.17–1.83). No significant changes over time were observed. Conclusions This study estimated the proportion of RIs and HIV incidence among MSM in the Netherlands using the RITA algorithm for the first time. The proportion of RIs was comparable to similar studies in other European countries such as the UK, which however used different methodology.

Background Prediction of Chlamydia trachomatis (Ct) infection is important to identify subjects at high risk. We aimed to develop Ct prediction rules with different levels of detail in information, i.e. with readily available registries only and with additional detailed questionnaires. Methods In the Chlamydia Screening Implementation (CSI) study all inhabitants of Rotterdam and Amsterdam aged 16–29 were invited yearly from 2008 until 2011 for home based urine testing. This resulted in 80,385 unique participants of whom 3,440 were infected. In addition to registry data (gender, age, ethnicity, neighbourhood level socioeconomic status [SES]) participants were asked to fill in a questionnaire on education, STI history, symptoms, partner information and sexual behaviour. We developed prediction rules based on registry risk factors only and with additional questionnaire risk factors by multilevel logistic regression to account for clustering within neighbourhoods. We assessed the discriminative ability by the area under the receiver operating characteristic curve (AUC). The models were internally validated with a bootstrap procedure. Results Strong registry based predictors for Ct infection were young age (especially for women) and either Surinamese, Antillean or Sub-Sahara-African ethnicity. SES was of minor importance especially when questionnaire predictors were added. From the questionnaire, low to intermediate education level, ethnicity of the partner (non-Dutch) and having sex with casual partners showed strong associations with Ct infection. The AUC at internal validation was 0.67 based on registry risk factors only and 0.75 when questionnaire risk factors were added. To find 80% of the Chlamydia infections approximately 50% of the population needed to be screened when using the prediction rule including questionnaire risk factors. Conclusion The registry based prediction rule can potentially facilitate selective Ct screening at population level, with further refinement at the individual level by including questionnaire risk factors.

Background Partner notification (PN) is seen as a vital tool to break HIV/STI transmission chains. In the Netherlands, studies assessing PN effectiveness were lacking. Here, we evaluated effectiveness of current PN practises in STI clinics to provide recommendations to further enhance PN. Methods PN outcomes were collected through a newly developed registration system from index patients with HIV, syphilis, and gonorrhoea visiting five STI centres in 2010–2011. PN outcomes for men who have sex with men (MSM) and heterosexuals included partners: at risk, notifiable, notified, tested and diagnosed with STI/HIV. Results Of all index patients newly diagnosed with HIV/STI (N = 388) for whom PN was indicated, 312 MSM, 35 heterosexual men and 41 women reported respectively 2042, 126 and 82 partners at risk (6.5, 3.6 and 2.0 partners per index). Proportions of notifiable partners differed significantly by sexual preference (MSM: 46%, heterosexual men: 63%, women: 87%, p Conclusions The major challenge in PN among MSM remains the large proportion of unnotifiable (anonymous) partners, whereas among heterosexuals a higher percentage partners were lost during the actual notification process. Therefore, newly developed interventions, e.g.anonymous internet-based PN or PN training, should be tailored to specific risk-groups.

Objective To assess the association between chlamydia (CT)-test results and subsequent sexual risk behaviour change in a register based Chlamydia Screening (CSI) programme consisting of four screening rounds. Methods All participants in the CSI programme, who had completed questionnaires and corresponding CT-test results in ≥ 2 rounds, were included. Measurements in round four were excluded, because of low participation rates. Sexual risk behaviour parameters contained the use of condoms, number of partners and having casual, concurrent or new partners. Generalised estimating equations (GEE) were used to assess the influence of the test result on the change in sexual risk behaviour in the subsequent round. Analysis were adjusted for sexual preference, having a steady or casual partner, age and number of rounds participated. Results Of 9360 included participants, 80.5% (n = 7536) and 19.5% (n = 1824) completed CT-testing and questionnaires in respectively two and three rounds. Across all rounds, a significant difference in change of sexual risk behaviour could be found: participants who tested CT-positive in the previous round more often reported reduced risk behaviour (more use of condoms with a casual partner (32.1% vs 24.1%, p = 0.018), less having sex with a casual partner (21.7% vs 15.3%, p = 0.001), lower number of sex partners (38.5% vs 24.7%, p Conclusion Sexual risk behaviour change was associated with previous CT-test results. Participants who tested CT-positive more often positively changed their sexual risk behaviour compared to participants with a negative test result in the previous round.

Background In cervical cancer screening, uptake of screening is approximately 10% higher if a woman is invited by her General Practitioner (GP) compared to invitation by Municipal Public Health Service (PHS). A large register-based selective Chlamydia Screening Programme is implemented in Amsterdam (Netherlands) since 2008 by the PHS. We wanted to evaluate whether response rates in Chlamydia screening where higher if invitational letters are sent by a persons9 GP and not by PHS. Methods Based on the municipal registers, annually all 140 000 persons in Amsterdam aged 16–29 yr are invited with a postal letter to participate. Further procedures are internet-based: requesting test-packages, obtaining results, even partner-referral, can be realised via the internet and the unique identifier provided in the personal letter. In one part of the city, the Southeast inner-city area, GP-registers of six health centre are matched with the list of invitees extracted from the municipal register. In the invitational letter these matched eligible9s are personally addressed by their GP and not by the physician of the PHS. Participation rates from invitees of GP and PHS in the same geographical town area are compared in three screenings-rounds (r 3 not yet fully completed). Results In these four town area9s in each screening round annually 13 500 persons are invited, of which 35% by the GP and 65% by PHS. In screenings-round 1, the response to invitations by the GP was slightly higher than the response to invitations sent by the PHS in 3 out of 4 neighbourhoods where this was piloted (overall GPs: 16.2% [range: 15.3%–29.1%]; overall PHS: 14.9% [14.4%–21.6%], p=0.023). In round 2 and 3 the difference was not significant (GP vs MHS: r2 10.3%–10.2%; r3 9.5% vs 9.4%). (Abstract O5-S4.01 figure 1). Conclusions In the first screening-round uptake was slightly higher among GP-invited, but this effect was lost in subsequent screening-rounds. Inviting universally via the PHS is logistically easier and yields the same response rate.

Background Chlamydia 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). Methods From 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. Results The 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). Conclusions The 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.