Changes in Genital HPV Prevalence during 12 Years Girls-Only Bivalent HPV Vaccination: Results from a Biennial Repeated Cross-Sectional Study.

BACKGROUND: From 2009 until 2021, bivalent HPV vaccination was offered only to girls in the Netherlands. We aimed to study the impact of girls-only HPV vaccination on genital HPV prevalence among young adults. METHODS AND FINDINGS: PASSYON is a biennial repeated cross-sectional study (2009-21) among sexual health clinic clients aged 16-24 years old. Questionnaires elicited data on demographics, sexual behaviour and HPV vaccination status. Genital samples were collected and analysed using a PCR-based assay (SPF10-LiPA25). Type-specific prevalence trends of 12 high-risk (hr) genotypes were analysed as the adjusted average annual change (aAAC), estimated using Poisson GEE models. The relation between aAAC and phylogenetic distance to HPV-16/18 was assessed by means of regression and rank correlation analysis. Questionnaires and genital samples were collected from 8,889 females and 3,300 heterosexual males (HM). 4,829 females reported to be unvaccinated (54·3%). Among females (irrespective of vaccination status), prevalences of HPV-16/18/31/33/35/45 decreased significantly over time. Increasing trends were observed for HPV-39/52/56. Among both HM and unvaccinated females HPV-16/18 prevalence significantly declined, as did HPV-31 among HM. In contrast, HPV-52/58 increased significantly among HM and unvaccinated females. The type-specific aAAC correlated well with the phylogenetic distance to HPV-16/18. CONCLUSIONS: During twelve years girls-only bivalent HPV vaccination in the Netherlands, decreasing trends of the vaccine types and cross-protected types were observed among females. Herd protection of vaccine-types was observed for HM and unvaccinated females, and one cross-protected type for HM. Increasing prevalence trends of HPV types with large phylogenetic distance to the vaccine types might indicate type-replacement.

Investigating possibilities for surveillance of long term chlamydia complications in the Netherlands: A qualitative study.

OBJECTIVES: Chlamydia trachomatis (chlamydia) is one of the most reported bacterial sexually transmitted infections (STI) worldwide. Chlamydia can cause long term complications such as pelvic inflammatory disease (PID), ectopic pregnancy (EP) and tubal factor infertility (TFI). Changing testing strategies, for example reduced asymptomatic testing, influence chlamydia surveillance, highlighting the need for exploring alternative ways of monitoring chlamydia. We investigated the possibility of introducing routine surveillance of chlamydia related long term complications. METHODS: A qualitative study including 15 in-depth interviews with a purposive sample of gynaecologists, general practitioners (GP), sexual health and emergency doctors was conducted in the Netherlands in 2021-2022. A semi-structured interview guide focused on experiences with diagnosis and registration of PID, EP and TFI and how a change in asymptomatic chlamydia testing strategy might influence this. Interviews were transcribed and analysed using a thematic approach. RESULTS: Analysis showed that gynaecologists most frequently reported diagnosing PID, EP and TFI. Other professions rarely diagnose these complications, with emergency doctors only diagnosing EP. Most respondents reported unique registration codes for PID and EP, but the coding for TFI is more ambiguous. They reflected that diagnosis and registration of PID, EP and TFI are handled differently within their professions. Most respondents acknowledged registration in diagnostic codes as a useful surveillance tool. They expressed concerns in representativeness (e.g. differences in interpretation of diagnosis criteria) and data quality for surveillance. CONCLUSIONS: Patient files of gynaecologists are likely to be most complete for monitoring trends of diagnosed chlamydia related long term complications in the Netherlands. However, when establishing a chlamydia complication surveillance system, professionals should be engaged in further standardizing diagnosis and registration practices. This will improve the quality and interpretability of complication surveillance and facilitate comparison between countries.

Prevalence and risk factors for HPV seropositivity and anogenital DNA positivity among men who have sex with men: a repeated cross-sectional study.

OBJECTIVES: This study aimed to assess associations of potential risk factors with human papillomavirus (HPV) seropositivity among men who have sex with men (MSM) and compare these to risk factors for anal and penile (HPV) deoxyribonucleic acid (DNA)-positivity in the same study population. METHODS: Seropositivity and anal and penile HPV DNA-positivity were determined for seven high-risk HPV genotypes for MSM aged 16-24 years participating in Papillomavirus Surveillance among STI clinic Youngsters in the Netherlands (PASSYON) 2009-2021. Logistic regression models were conducted to assess risk factors for seropositivity, anal and penile HPV DNA-positivity. RESULTS: Overall, 1019 MSM were included. HPV-16 and -18 were most common for serology, and anal and penile HPV DNA-positivity. Although no clear similarities were observed for most risk factors for HPV seropositivity and anal or penile DNA positivity, receptive anal intercourse (RAI) was the strongest associated risk factor for both seropositivity ('RAI ever' adjusted odds ratio [aOR] 3.50, 95% confidence interval [CI] 1.56-7.88; 'RAI previous 6 months' aOR 2.17, 95% CI 1.44-3.26) and anal DNA-positivity ('RAI previous 6 months' aOR 1.67, 95% CI 1.09-2.56). CONCLUSIONS: Our study is suggestive of site-specific immune response after HPV infection; RAI might lead to anal HPV infections and consequently to seroconversion. Finally, as the two genotypes that are most oncogenic and preventable by all HPV vaccines were most common, our results underline the importance of gender-neutral vaccination.

Interventions Promoting Condom Use Among Youth: A Systematic Review.

In many European and other high-income, Western countries, condom use has been decreasing among youth. A variety of promotional strategies to increase condom use exists. Our systematic review aimed to identify effective elements in interventions aimed at increasing condom use in youth. We searched databases (2010-2021) for intervention studies promoting condom use among youth in Western, high-income countries. The primary outcome was condom use; the secondary outcome was sexually transmitted infection (STI) diagnoses. Effectiveness per intervention was defined based on the percentage of comparisons that showed significant increases in condom use and significant decreases in STIs. We compared the effectiveness of interventions for different participant-, intervention- and methodological characteristics. We included 74 papers describing 85 interventions in the review. Overall, the median intervention effectiveness was 33.3% (interquartile range = 0%-66.7%) for condom use and 0% (interquartile range = 0%-100%) for STI diagnoses. Intervention effectiveness for condom use was significantly higher in interventions tailored towards females and males specifically, compared with interventions applied to both sexes combined. Our findings show the difficulty in designing effective interventions to increase condom use among youth. Interventions aimed at either females or males were more effective in increasing condom use.

Diagnostic accuracy of HPV16 early antigen serology for HPV-driven oropharyngeal cancer is independent of age and sex.

A growing proportion of head and neck cancer (HNC), especially oropharyngeal cancer (OPC), is caused by human papillomavirus (HPV). There are several markers for HPV-driven HNC, one being HPV early antigen serology. We aimed to investigate the diagnostic accuracy of HPV serology and its performance across patient characteristics. Data from the VOYAGER consortium was used, which comprises five studies on HNC from North America and Europe. Diagnostic accuracy, that is, sensitivity, specificity, Cohen's kappa and correctly classified proportions of HPV16 E6 serology, was assessed for OPC and other HNC using p16INK4a immunohistochemistry (p16), HPV in situ hybridization (ISH) and HPV PCR as reference methods. Stratified analyses were performed for variables including age, sex, smoking and alcohol use, to test the robustness of diagnostic accuracy. A risk-factor analysis based on serology was conducted, comparing HPV-driven to non-HPV-driven OPC. Overall, HPV serology had a sensitivity of 86.8% (95% CI 85.1-88.3) and specificity of 91.2% (95% CI 88.6-93.4) for HPV-driven OPC using p16 as a reference method. In stratified analyses, diagnostic accuracy remained consistent across sex and different age groups. Sensitivity was lower for heavy smokers (77.7%), OPC without lymph node involvement (74.4%) and the ARCAGE study (66.7%), while specificity decreased for cases with <10 pack-years (72.1%). The risk-factor model included study, year of diagnosis, age, sex, BMI, alcohol use, pack-years, TNM-T and TNM-N stage. HPV serology is a robust biomarker for HPV-driven OPC, and its diagnostic accuracy is independent of age and sex. Future research is suggested on the influence of smoking on HPV antibody levels.

HIV and syphilis testing for women and heterosexual men aged above 25 years in the Netherlands: possibilities for targeted testing at sexual health centres.

OBJECTIVES: Targeted testing policy for HIV/syphilis at Dutch sexual health centres (SHCs) was evaluated for its efficiency in younger heterosexuals but not for heterosexuals ≥25 years. Currently, all older heterosexuals are tested for HIV/syphilis at SHCs. To explore possibilities for increased efficiency of testing in heterosexuals aged >25 years, this study aimed to identify determinants of HIV and syphilis diagnoses that could be used in targeted testing strategies. DESIGN: An observational study using surveillance data from all Dutch SHC. PARTICIPANTS: Women and heterosexual men aged >25 years visiting SHC between 2015 and 2021. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was HIV/syphilis diagnosis, determinants of a diagnosis were analysed. Based on these determinants and their applicability in SHC practice, different targeted testing scenarios were evaluated. For each scenario, the percentage of consultations involving HIV and syphilis testing and the total amount of missed HIV and syphilis diagnoses were calculated. RESULTS: 109 122 consultations were included among 75 718 individuals. The strongest determinants of HIV/syphilis diagnosis were HIV/syphilis-specific symptoms (adjusted OR (aOR) 34.9 (24.1-50.2)) and receiving partner notification (aOR 18.3 (13.2-25.2)), followed by low/middle education level (aOR 2.8 (2.0-4.0)), male sex (aOR 2.2 (1.6-3.0)) and age ≥30 years (aOR 1.8 (1.3-2.5)). When applying feasible determinants to targeted testing scenarios, HIV/syphilis testing would have been conducted in 54.5% of all consultations, missing 2 HIV and 3 syphilis diagnoses annually (13.4% and 11.4% of all diagnoses, respectively). In the scenario with the lowest number of missed HIV/syphilis diagnoses (0.3 HIV and 2 syphilis diagnoses annually), HIV/syphilis testing would have been conducted in 74.2% of all consultations. CONCLUSIONS: In any targeted testing scenario studied, HIV and/or syphilis diagnoses would have been missed. This raises the question whether it is acceptable to put any of these scenarios into practice. This study contributes to a discussion about the impact of targeted testing policy.

Projecting the development of antimicrobial resistance in Neisseria gonorrhoeae from antimicrobial surveillance data: a mathematical modelling study.

BACKGROUND: The World Health Organization recommends changing the first-line antimicrobial treatment for gonorrhoea when ≥ 5% of Neisseria gonorrhoeae cases fail treatment or are resistant. Susceptibility to ceftriaxone, the last remaining treatment option has been decreasing in many countries. We used antimicrobial resistance surveillance data and developed mathematical models to project the time to reach the 5% threshold for resistance to first-line antimicrobials used for N. gonorrhoeae. METHODS: We used data from the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) in England and Wales from 2000-2018 about minimum inhibitory concentrations (MIC) for ciprofloxacin, azithromycin, cefixime and ceftriaxone and antimicrobial treatment in two groups, heterosexual men and women (HMW) and men who have sex with men (MSM). We developed two susceptible-infected-susceptible models to fit these data and produce projections of the proportion of resistance until 2030. The single-step model represents the situation in which a single mutation results in antimicrobial resistance. In the multi-step model, the sequential accumulation of resistance mutations is reflected by changes in the MIC distribution. RESULTS: The single-step model described resistance to ciprofloxacin well. Both single-step and multi-step models could describe azithromycin and cefixime resistance, with projected resistance levels higher with the multi-step than the single step model. For ceftriaxone, with very few observed cases of full resistance, the multi-step model was needed to describe long-term dynamics of resistance. Extrapolating from the observed upward drift in MIC values, the multi-step model projected ≥ 5% resistance to ceftriaxone could be reached by 2030, based on treatment pressure alone. Ceftriaxone resistance was projected to rise to 13.2% (95% credible interval [CrI]: 0.7-44.8%) among HMW and 19.6% (95%CrI: 2.6-54.4%) among MSM by 2030. CONCLUSIONS: New first-line antimicrobials for gonorrhoea treatment are needed. In the meantime, public health authorities should strengthen surveillance for AMR in N. gonorrhoeae and implement strategies for continued antimicrobial stewardship. Our models show the utility of long-term representative surveillance of gonococcal antimicrobial susceptibility data and can be adapted for use in, and for comparison with, other countries.

Global Type-Specific Genital Human Papillomavirus Prevalence in Men, by Sexual Orientation: A Systematic Review and Meta-Analysis.

BACKGROUND: Knowledge on genital type-specific human papillomavirus (HPV) prevalence among men is important for prevention of HPV-related cancers and other diseases. Men who have sex with men (MSM) have higher anal prevalence than men who have sex with women only (MSW) but for genital HPV this is unclear. We performed a systematic review and meta-analysis of type-specific genital HPV prevalence among men, by sexual orientation. METHODS: MEDLINE and Embase were used for searching publications reporting on male genital HPV prevalence with data from November 2011 onwards. A random-effects meta-analysis was conducted estimating pooled type-specific and grouped external genital and urethral HPV prevalence. Subgroup analyses were conducted for sexual orientation. RESULTS: Twenty-nine studies were eligible. Of those, 13 studies reported prevalence among MSM, 5 among MSW, and 13 studies did not stratify by sexual orientation. The most common genotypes were HPV-6 and HPV-16 for both anatomical locations, although heterogeneity was high. HPV prevalence was similar among studies reporting on MSW, MSM, and men with unknown sexual orientation. CONCLUSIONS: Genital HPV is common among men, with HPV-6 and HPV-16 being the most common genotypes. Type-specific HPV genital prevalence appears to be similar among MSM and MSW, which contrasts with earlier findings on anal HPV.

Identifying Sexually Transmitted Infection Risk Groups Based on Behavioral and Psychological Characteristics Among Heterosexuals During the COVID-19 Pandemic.

BACKGROUND: Measures to reduce coronavirus disease (COVID-19) transmission may impact sexual health. We aimed to examine the impact of COVID-19 on sexual behavior and sexually transmitted infection (STI) testing and to characterize individuals who were at high STI risk. METHODS: Dutch heterosexual males and females who participated in a cohort study in 2016 to 2018 were invited to fill out 2 questionnaires again in 2020 (age, 21-28 years). We used behavioral and psychological data from: prelockdown (September 2019 to February 2020), lockdown (March to May 2020), and postlockdown (June to August 2020). Behavior change was compared between subgroups identified with latent class analysis. RESULTS: Four latent classes were identified (n = 238). Individuals in class 1 (48% of study population) and class 2 (36%) were at low STI risk and reported mostly steady partnerships. Individuals in class 3 (9%) and class 4 (7%) reported multiple casual partners prelockdown. Class 4 was characterized by lower condom use and health goals, negative infection prevention attitudes, and higher impulsiveness compared with class 3. Furthermore, same/increased partner numbers during lockdown (class 3, 18%; class 4, 56%) and postlockdown (class 3, 36%; class 4, 42%) compared with prelockdown was often reported. Of individuals who wanted an STI test during the pandemic, 62% in class 3 and 56% in class 4 did not get tested, mainly because they were unable to get an appointment. CONCLUSIONS: A subgroup of individuals, characterized by low health goals, negative infection prevention attitudes, and high impulsiveness, engaged in high-risk behavior during the pandemic. Identifying these individuals may help provide appropriate health care during strict lockdowns and after relaxation of measures.

Increased risk of subsequent chlamydia infection among women not tested at the anorectal anatomical location.

BACKGROUND: Universal anorectal testing for Chlamydia trachomatis (chlamydia) among women is not recommended in many countries, while anorectal chlamydia infections are common. Missed anorectal infections might cause sequelae at the genital site if autoinoculation from the anorectum is possible, but evidence is limited. This study investigates the association between potentially missed anorectal infections and subsequent genital chlamydia infections in women, using not being tested at the anorectal site as a proxy for having a potentially missed anorectal infection. METHODS: We included all women with a repeat chlamydia test within 1 year (with at least a genital test) from the Dutch sexual health centre surveillance between 2014 and 2019. Multilevel logistic regression analyses were used to identify determinants of genital chlamydia infection at the repeat test, with anorectal testing at the previous chlamydia test as the main determinant. RESULTS: A total of 40 217 women were included in the analyses, of whom 15.4% tested chlamydia-positive genitally at their second test. Not being tested anorectally at the first test was an independent risk factor for genital chlamydia infection at the repeat test (adjusted OR 1.24, 95% CI 1.15 to 1.33). This association was in the same range as most other significant risk factors in the model: low education level, no condom use, STI symptoms and previous STI diagnosis. Young age (<20 years) (2.67, 2.39-2.98) and those who received partner notification (3.11, 2.91-3.31) showed stronger associations. The findings were robust; correcting for interactions and a sensitivity analysis stratifying by chlamydia infection at first visit did not show significant differences in the adjusted OR of not being tested anorectally at first test. CONCLUSION: The results are suggestive of an autoinoculation process from the anorectal to the genital anatomical site in women. To enhance chlamydia control, future studies on the role of extragenital testing and autoinoculation in chlamydia transmission are needed.

Time for change: Transitions between HIV risk levels and determinants of behavior change in men who have sex with men.

As individual sexual behavior is variable over time, the timing of interventions might be vital to reducing HIV transmission. We aimed to investigate transitions between HIV risk levels among men who have sex with men (MSM), and identify determinants associated with behavior change. Participants in a longitudinal cohort study among HIV-negative MSM (Amsterdam Cohort Studies) completed questionnaires about their sexual behavior during biannual visits (2008-2017). Visits were assigned to different HIV risk levels, based on latent classes of behavior. We modelled transitions between risk levels, and identified determinants associated with these transitions at the visit preceding the transition using multi-state Markov models. Based on 7,865 visits of 767 participants, we classified three risk levels: low (73% of visits), medium (22%), and high risk (5%). For MSM at low risk, the six-month probability of increasing risk was 0.11. For MSM at medium risk, the probability of increasing to high risk was 0.08, while the probability of decreasing to low risk was 0.33. For MSM at high risk, the probability of decreasing risk was 0.43. Chemsex, erection stimulants and poppers, high HIV risk perception, and recent STI diagnosis were associated with increased risk at the next visit. High HIV risk perception and young age were associated with decreasing risk. Although the majority of MSM showed no behavior change, a considerable proportion increased HIV risk. Determinants associated with behavior change may help to identify MSM who are likely to increase risk in the near future and target interventions at these individuals, thereby reducing HIV transmission.

Where to go to in chlamydia control? From infection control towards infectious disease control.

OBJECTIVES: The clinical and public health relevance of widespread case finding by testing for asymptomatic chlamydia infections is under debate. We wanted to explore future directions for chlamydia control and generate insights that might guide for evidence-based strategies. In particular, we wanted to know the extent to which we should pursue testing for asymptomatic infections at both genital and extragenital sites. METHODS: We synthesised findings from published literature and from discussions among national and international chlamydia experts during an invitational workshop. We described changing perceptions in chlamydia control to inform the development of recommendations for future avenues for chlamydia control in the Netherlands. RESULTS: Despite implementing a range of interventions to control chlamydia, there is no practice-based evidence that population prevalence can be reduced by screening programmes or widespread opportunistic testing. There is limited evidence about the beneficial effect of testing on pelvic inflammatory disease prevention. The risk of tubal factor infertility resulting from chlamydia infection is low and evidence on the preventable fraction remains uncertain. Overdiagnosis and overtreatment with antibiotics for self-limiting and non-viable infections have contributed to antimicrobial resistance in other pathogens and may affect oral, anal and genital microbiota. These changing insights could affect the outcome of previous cost-effectiveness analysis. CONCLUSION: The balance between benefits and harms of widespread testing to detect asymptomatic chlamydia infections is changing. The opinion of our expert group deviates from the existing paradigm of 'test and treat' and suggests that future strategies should reduce, rather than expand, the role of widespread testing for asymptomatic chlamydia infections.

Modelling the impact of tailored behavioural interventions on chlamydia transmission.

Behavioural interventions tailored to psychological characteristics of an individual can effectively achieve risk-reducing behaviour. The impact of tailored interventions on population-level chlamydia prevalence is unknown. We aimed to assess the impact on overall chlamydia prevalence five years after the introduction of an intervention aimed at increasing self-efficacy, social norms, attitudes and intentions towards condom use (i.e., condom intervention), and an intervention aimed at increasing health goals and decreasing impulsiveness (i.e., impulsiveness intervention). A pair model, informed by longitudinal psychological and behavioural data of young heterosexuals visiting sexual health centers, with susceptible-infected-susceptible structure was developed. The intervention effect was defined as an increased proportion of each subgroup moving to the desired subgroup (i.e., lower risk subgroup). Interventions tailored to subgroup-specific characteristics, assuming differential intervention effects in each subgroup, more effectively reduced overall chlamydia prevalence compared to non-tailored interventions. The most effective intervention was the tailored condom intervention, which was assumed to result in a relative reduction in chlamydia prevalence of 18% versus 12% in the non-tailored scenario. Thus, it is important to assess multiple psychological and behavioural characteristics of individuals. Tailored interventions may be more successful in achieving risk-reducing behaviour, and consequently, reduce chlamydia prevalence more effectively.

The Rhythm of Risk: Sexual Behaviour, PrEP Use and HIV Risk Perception Between 1999 and 2018 Among Men Who Have Sex with Men in Amsterdam, The Netherlands.

HIV risk perception plays a crucial role in the uptake of preventive strategies. We investigated how risk perception and its determinants changed between 1999 and 2018 in an open, prospective cohort of 1323 HIV-negative men who have sex with men (MSM). Risk perception, defined as the perceived likelihood of acquiring HIV in the past 6 months, changed over time: being relatively lower in 2008-2011, higher in 2012-2016, and again lower in 2017-2018. Irrespective of calendar year, condomless anal intercourse (AI) with casual partners and high numbers of partners were associated with higher risk perception. In 2017-2018, condomless receptive AI with a partner living with HIV was no longer associated with risk perception, while PrEP use and condomless AI with a steady partner were associated with lower risk perception. We showed that risk perception has fluctuated among MSM in the past 20 years. The Undetectable equals Untransmittable statement and PrEP coincided with lower perceived risk.

The impact of STI test results and face-to-face consultations on subsequent behavior and psychological characteristics.

Sexually transmitted infection (STI) testing without face-to-face counselling is increasingly offered at sexual health centers (SHC), and ordering self-sampling tests online is becoming more popular. However, the impact of testing without counselling on behavior is unknown. We examine the impact of STI testing with and without consultation and the combined effect of a positive test result and treatment consultation, on behavioral and psychological characteristics over time. Data from a longitudinal study among heterosexual SHC visitors aged 18-24 years was used. The impact of a test consultation (participants who tested chlamydia negative with vs. without consultation) and treatment consultation/positive test result (participants who tested chlamydia positive vs. negative), was assessed by comparing behavioral and psychological characteristics before testing (baseline), and at three-week and six-month follow-up, using generalized estimating equation models. Changes after testing were similar between participants who tested chlamydia negative with and without test consultation, namely decreased risk perception, shame, number of partners, and increased knowledge. However, participants who tested chlamydia positive reported stronger increases in health goals and intentions towards condom use, and stronger decreases in the number of partners and stigma, compared to participants who tested negative. Furthermore, condom use increased in chlamydia positive, and decreased in chlamydia negative participants. A treatment consultation/positive test result had a risk-reducing impact on behavioral and psychological characteristics, whereas the impact of a test consultation was limited. Since the majority of young heterosexuals test chlamydia negative, alternative interventions (e.g., online) achieving risk-reducing behavior change targeted to individuals who tested negative are needed.

Longitudinal Patterns of Sexually Transmitted Infection Risk Based on Psychological Characteristics and Sexual Behavior in Heterosexual Sexually Transmitted Infection Clinic Visitors.

BACKGROUND: Great heterogeneity in sexually transmitted infections (STI) risk exists, and investigating individual-level characteristics related to changes in STI risk over time might facilitate the development and implementation of effective evidence-based behavior change interventions. The aim of this study was to identify longitudinal patterns of STI risk based on psychological and behavioral characteristics. METHODS: A longitudinal study was conducted among heterosexual STI clinic visitors aged 18 to 24 years. Latent classes based on behavioral and psychological characteristics at baseline, and transitions from 1 latent class to another at 3-week, 6-month, and 1-year follow-up, were identified using latent transition analysis. RESULTS: Four latent classes were identified that could be differentiated by psychological and behavioral characteristics and STI risk: overall low-risk (10%), insecure high-risk (21%), condom-users (38%), and confident high-risk (31%). Although the majority of the total study population did not move to another latent class over time, the size of the overall low-risk group increased from 10% at baseline to 30% after 1 year. This was mainly due to transitions from the insecure high-risk, condom-users, and confident high-risk class at 3-week follow-up to the overall low-risk class at 6-month follow-up. CONCLUSIONS: Distinct subgroups among heterosexual STI clinic visitors can be differentiated from each other by multiple psychological and behavioral characteristics, and these characteristics reflecting the risk of acquiring STI are consistent over the course of 1 year in most individuals. An integral approach, adapting behavioral interventions to match multiple psychological and behavioral characteristics of high-risk subgroups, might be more effective in controlling STI transmission.

Placing sexually transmitted infection surveillance data in perspective by using national probability sample surveys.

BACKGROUND: Many European countries do not have comprehensive sexually transmitted infection (STI) surveillance in place. The objective was to investigate whether national probability sample surveys are useful in placing STI surveillance into perspective. METHODS: We used data from the Dutch national cross-sectional probability sample survey on sexual health 2016 (18-34-year-old sexually active individuals). Descriptive analyses were performed regarding STI testing (last year). Test numbers were extrapolated from the survey and compared with surveillance data from sexual health centres (SHCs) (complete) and general practitioners (GPs) (representative estimates from 7% of all GPs). Statistical differences in characteristics between SHC attendees and general population (according to weighted survey participants) were determined using χ2 statistic. Predictors of recent testing at GPs or SHCs were determined using multinomial multivariable logistic regression. RESULTS: Of the 17 222 survey invitees, 3217 (19%) were eligible for analyses. Testing uptake was higher in women (17.2%, 14.8-20.0%) than men (11.5%, 9.1-14.3%). The majority of tests were conducted by GPs followed by SHCs and hospitals. Number of tests extrapolated from the survey was similar to SHC surveillance data, but higher than GP surveillance data (women only). Testing at SHCs was associated with high-risk behaviour and with living in highly urbanized areas. Low education level and older age were, next to high-risk behaviour factors, determinants of testing at GPs. CONCLUSIONS: National probability sample surveys are useful for placing STI surveillance data into perspective by providing insights in testing patterns in the general population and identifying strengths and weaknesses of national surveillance systems.

Who drops out and when? Predictors of non-response and loss to follow-up in a longitudinal cohort study among STI clinic visitors.

INTRODUCTION: Response rates in health research are declining, and low response rates could result in biased outcomes when population characteristics of participants systematically differ from the non-respondents. Few studies have examined key factors of non-response beyond demographic characteristics, such as behavioral and psychological factors. The aim of the current study was to identify predictors of non-response and loss to follow-up in a longitudinal sexual health study. MATERIALS AND METHODS: A longitudinal cohort study (iMPaCT) was conducted from November 2016 to July 2018 among heterosexual STI clinic visitors aged 18-24 years. At four different time points in one year, data was collected on sexual behavior, psychological determinants and chlamydia infections. The national STI surveillance database provided data on demographic, behavioral and sexual health-related characteristics for non-respondents. Predictors of non-response at baseline and of loss to follow-up were identified using multivariable logistic regression analyses. RESULTS: In total, 13,658 STI clinic visitors were eligible to participate, of which 1,063 (8%) participated. Male gender, low/medium education level, young age (≤ 20 years) and having a non-Dutch migration background were significant predictors of non-response at baseline. Furthermore, non-respondents at baseline were more likely to report STI-related symptoms, to have been notified by a partner, to have had condomless sex, and to have had ≤ 2 partners in the past six months, compared to participants. Psychological predictors of loss to follow-up differed between STI clinic regions, but low perceived importance of health at baseline was associated with loss to follow-up in all regions. The baseline chlamydia positivity rate was significantly higher in the non-respondents (17%) compared to the participants (14%), but was not a predictor of loss to follow-up. DISCUSSION: Targeted recruitment aimed at underrepresented groups in the population based on demographic, behavioral and psychological characteristics, might be necessary to decrease loss to follow-up, and to prevent non-response bias in health research.

Impact of sexual trajectories of men who have sex with men on the reduction in HIV transmission by pre-exposure prophylaxis.

Changes in sexual risk behavior over the life course in men who have sex with men (MSM) can influence population-level intervention efficacy. Our objective was to investigate the impact of incorporating sexual trajectories describing long-term changes in risk levels on the reduction in HIV prevalence by pre-exposure prophylaxis (PrEP) among MSM. Based on the Amsterdam Cohort Study data, we developed two models of HIV transmission in a population stratified by sexual behavior. In the first model, individuals were stratified into low, medium and high risk levels and did not change their risk levels. The second model had the same stratification but incorporated additionally three types of sexual behavior trajectories. The models assumed universal antiretroviral treatment of HIV+ MSM, and PrEP use by high risk HIV- MSM. We computed the relative reduction in HIV prevalence in both models for annual PrEP uptakes of 10% to 80% at different time points after PrEP introduction. We then investigated the impact of sexual trajectories on the effectiveness of PrEP intervention. The impact of sexual trajectories on the overall prevalence and prevalence in individuals at low, medium and high risk levels varied with PrEP uptake and time after PrEP introduction. Compared to the model without sexual trajectories, the model with trajectories predicted a higher impact of PrEP on the overall prevalence, and on the prevalence among the medium and high risk individuals. In low risk individuals, there was more reduction in prevalence during the first 15 years of PrEP intervention if sexual trajectories were not incorporated in the model. After that point, at low risk level there was more reduction in the model with trajectories. In conclusion, our study predicts that sexual trajectories increase the estimated impact of PrEP on reducing HIV prevalence when compared to a population where risk levels do not change.