Prevalence of drug use during sex among swingers and perceived benefits and risks - a cross-sectional internet survey in the Netherlands.

OBJECTIVES: Drug use during sex has been associated with sexually transmitted infections (STI). While a growing body of research has investigated drug use during sex among men who have sex with men, data in swingers is limited. Swingers are heterosexual couples who have sex with others and singles who have sex with these couples. Our study assessed the prevalence of drug use during sex and perceived benefits and risks among swingers. METHODS: In 2018, 1005 swingers completed an online questionnaire that was advertised at Dutch swinger-websites. We assessed the associations between drug use during sex <6 months (any drug use excluding alcohol and erection medicines) and sociodemographic characteristics, alcohol use and condomless sex using backward multivariable logistic regression analysis. We compared drug use, motives, beliefs and experienced effects between heterosexual male, bisexual male and female drug-using swingers using χ2-tests. RESULTS: Drug use during sex was reported by 44% (443/1005): 51% in women, 44% in bisexual men and 39% in heterosexual men (P<0.01). Condomless vaginal (46%) and anal sex (22%) was higher in drug-using swingers (vs 34% and 13% in non-drug-using swingers, P<0.001). Among drug-using swingers, XTC (92%), GHB (76%) and laughing gas (69%) were mostly used. Prolonging sex (68%) and increasing arousal (66%) were the most reported motives. Most reported positive effects were feeling happy (78%) and increasing energy (78%). Ninety-four per cent considered drug use to be pleasurable. The most reported negative effect was feeling tired (53%), 7% reported that they might become addicted or felt uncomfortable having sex without drugs. CONCLUSION: This study among a large group of swingers shows that drug use during sex is highly prevalent. STI clinics should discuss drug use during sex among swingers and provide information on safer sex and drug use, while acknowledging the perceived benefits, such as the increased quality of sex.

Sexually transmitted infections in male heterosexual Dutch clients who visited German cross-border female sex workers; a 3 year retrospective study.

BACKGROUND: Some male heterosexual clients prefer to visit a cross-border Female Sex Worker (FSW) because of cheaper sex and unsafe sex practices, and may therefore be at risk for sexually transmitted infections (STI). The objective of this study was to assess whether having commercial cross-border sex is an independent risk factor for being diagnosed with a STI. METHODS: An observational retrospective study was performed using data of 8 Dutch STI clinics bordering Germany, between 2011 and 2013. All male heterosexual clients of FSWs were selected and data on country of FSW visit and occurrence of STI were used for multivariable regression analysis. RESULTS: The study population consisted of 2664 clients of FSW. Most clients visited the Netherlands (82.4%), followed by visits to another country (beyond cross-border) (9.9%) and cross-border visits (7.8%). Clients of FSW were less likely to be STI positive when they were younger than 25 years(OR = 0.6, 95%CI 0.4 to 0.8 25-44 years and OR = 0.5, 95%CI 0.4 to 0.7 older than 45 years), and more likely when they had 20 or more sex partners in the last 6 months (OR = 2.9, 95%CI 1.9 to 4.4), did not use a condom during last sexual contact (OR = 2.2, 95%CI 1.6 to 2.9) and made cross-border visits (OR = 1.7, 95%CI 1.1 to 2.6). CONCLUSIONS: As cross-border visits appears to be a novel independent risk factor for STI in clients of FSW, this group should therefore be advised on STI prevention.

Repeat Chlamydia trachomatis testing among heterosexual STI outpatient clinic visitors in the Netherlands: a longitudinal study.

BACKGROUND: Chlamydia infections are common in both men and women, are often asymptomatic and can cause serious complications. Repeat testing in high-risk groups is therefore indicated. In the Netherlands, guidelines on repeat chlamydia testing differ between testing facilities, and knowledge on repeat testing behaviour is limited. Here, we analyse the current repeat testing behaviour of heterosexual STI clinic visitors, and aim to identify groups for which repeat testing advice could be advantageous. METHODS: Longitudinal surveillance data from all Dutch STI outpatient clinics were used, which included all STI clinic consultations carried out among heterosexual men and women between June 2014 and December 2015. Repeat testing was defined as returning to the same STI clinic between 35 days and 12 months after initial consultation. We calculated chlamydia positivity at repeat test stratified by initial test result and time between consultations. Logistic regression analyses were used to identify predictors of repeat testing, and predictors of having a chlamydia positive repeat test. RESULTS: In total, 140,486 consultations in 75,487 women and 46,286 men were available for analyses. Overall, 15.4% of women and 11.1% of men returned to the STI clinic within the study period. Highest chlamydia positivity at repeat test was seen 3-5 months after initial positive test. Among both women and men, repeat testing was associated with non-Western ethnicity, having had more than two sex partners in the past 6 months, reporting STI symptoms, having a history of STI, and having a chlamydia positive initial test. Among repeat testers, chlamydia positive repeat test was most strongly associated with younger age, followed by a chlamydia positive initial test. CONCLUSIONS: Repeat testing most often resulted in a positive test result among young heterosexuals (<25) and heterosexuals of any age with a chlamydia infection at the initial consultation. Further efforts are needed to determine optimal repeat testing strategies.

Sexually transmitted infections among female sex workers tested at STI clinics in the Netherlands, 2006-2013.

BACKGROUND: Specialised sexually transmitted infection (STI) clinics in the Netherlands provide STI care for high-risk groups, including female sex workers (FSW), at the clinic and by outreach visiting commercial sex workplaces with a permit. The objective was to investigate the STI positivity rate and determinants of an STI diagnosis among FSW tested by STI clinics in the Netherlands. METHODS: Sexually transmitted infection clinics report demographic, behavioural and diagnostic information of every consultation to the National Institute for Public Health and the Environment. We analysed all consultations of FSW between 2006 and 2013. Trends in STI positivity rate (chlamydia, gonorrhoea, infectious syphilis, HIV and hepatitis B) were analysed using χ(2) for trend and logistic regression was used to analyse determinants associated with an STI diagnosis. Differences between consultations at the STI clinic and consultations during outreach were analysed using χ(2) tests. RESULTS: The positivity rate for any STI (overall 9.5 %) was stable from 2006 to 2013. Chlamydia positivity rate (overall 7.1 %) decreased (p < 0.001) and gonorrhoea positivity rate (overall 2.6 %) increased (p < 0.001). For gonorrhoea, the highest positivity rate was found oropharyngeal (2.0 %). Characteristics associated with STI were a younger age [adjusted odds ratio (aOR) 0.96, 95 % confidence interval (CI) 0.95-0.97 per year], a previous STI diagnosis (aOR 1.63, 95 % CI 1.38-1.92) and being notified for an STI by partner notification (aOR 2.61, 95 % CI 2.0-3.40). The STI positivity rate was significantly lower among FSW tested at outreach locations (8.6 %) compared to FSW tested at the STI clinic (11.7 %, p < 0.001). CONCLUSIONS: The STI positivity rate among FSW remained stable, but underlying this was a decreasing chlamydia trend and an increasing gonorrhoea trend, suggesting a shift in STI risks among FSW over time. Condom use during oral sex should be promoted since oropharyngeal gonorrhoea was frequently diagnosed and because of the potential spread of antimicrobial resistant gonococci.

Neurosyphilis in the mixed urban-rural community of the Netherlands.

OBJECTIVE: Neurosyphilis is caused by dissemination into the central nervous system of Treponema pallidum. Although the incidence of syphilis in the Netherlands has declined since the mid-1980s, syphilis has re-emerged, mainly in the urban centres. It is not known whether this also holds true for neurosyphilis. METHODS: The epidemiology of neurosyphilis in Dutch general hospitals in the period 1999-2010 was studied in a retrospective cohort study. Data from the Dutch sexually transmitted infection (STI) clinics were used to analyse the number of patients diagnosed with syphilis in this period. RESULTS: An incidence of neurosyphilis of 0.47 per 100 000 adults was calculated, corresponding with about 60 new cases per year. This incidence was higher in the western (urbanised) part of the Netherlands, as compared with the more rural areas (0.6 and 0.4, respectively). The number of patients diagnosed with syphilis in STI clinics increased from 150 to 700 cases in 2004 and decreased to 500 new cases in 2010. The sex ratio was in favour of men, yielding a percentage of 90% of the syphilis cases and of 75% of the neurosyphilitic cases. The incidence of neurosyphilis was highest in men aged 35-65 years, and in women aged 75 years and above. The most frequently reported clinical manifestation of neurosyphilis was tabes dorsalis. In this study, 15% of the patients were HIV seropositive. CONCLUSION: The incidence of neurosyphilis in a mixed urban-rural community such as the Netherlands is comparable to that in other European countries. Most patients are young, urban and men, and given the frequent atypical manifestations of the disease reintroduction of screening for neurosyphilis has to be considered.

Standard symptom- and sexual history-based testing misses anorectal Chlamydia trachomatis and neisseria gonorrhoeae infections in swingers and men who have sex with men.

BACKGROUND: Currently, individuals at risk for sexually transmitted diseases (STDs) are tested extragenitally only if indicated, most often when there is a history of self-reported symptoms or self-reported anal sex. The sensitivity of such selective symptom- and sexual history-based testing for detection of anorectal STD has not been determined. METHODS: All men having sex with men (MSM) and swingers (heterosexual couples who have sex with other heterosexual couples and their self-identified heterosexual sex partners) attending our STD clinic (consults: n = 1690) from January 2010 until February 2011 were universally tested for urogenital, anorectal, and oropharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae infections (STD). We compared STD prevalence at anorectal site based on universal versus selective testing. RESULTS: Sensitivity of selective symptom- and sexual history-based testing for anorectal STD was 52% for homosexual MSM, 40% for bisexual MSM, 43% for bisexual male swingers, 40% for heterosexual male swingers, and 47% for female swingers. CONCLUSIONS: Universal testing of STD clinic clients who were MSM and swingers yielded more than half of all anorectal STD infections and is more sensitive for identifying anorectal STD infections compared with selective testing. Universal testing may be a more effective strategy for interrupting the ongoing transmission in high-risk sexual networks.

New statistical technique for analyzing MIC-based susceptibility data.

Seventeen laboratories participated in a cooperative study to validate the regional susceptibility testing of Neisseria gonorrhoeae in The Netherlands. International reference strains were distributed. Each laboratory determined the MICs of ciprofloxacin, penicillin, and tetracycline, for each strain by Etest. To explore a more transparent assessment of quality and comparability, a statistical regression model was fitted to the data that accounted for the censoring of the MICs. The mean MICs found by all of the laboratories except three were closer than one 2-fold dilution step to the overall mean, and the mean MICs of each antimicrobial agent were close to the MICs for the international reference strains. This approach provided an efficient tool to analyze the performance of the Dutch decentralized gonococcal resistance monitoring system and confirmed good and comparable standards.

STD coinfections in The Netherlands: Specific sexual networks at highest risk.

BACKGROUND: Specific subpopulations infected with multiple bacterial sexually transmitted diseases (STDs) may facilitate ongoing STD transmission. To identify these subpopulations we determined the extent of concurrent incident STD infections and their risk factors among the high-risk population seen at Dutch STD clinics. METHODS: STD surveillance data submitted routinely by STD clinics to the National Institute for Public Health on demographics, sexual behavior, STD testing, and diagnoses for the period 2004-2007 were analyzed. RESULTS: Bacterial STD coinfections were diagnosed concurrently in 2120 (7%) of the 31,754 incident bacterial STD diagnoses (chlamydia, gonorrhea, infectious syphilis). In univariate logistic regression analyses, coinfections were significantly more often diagnosed in men who have sex with men (MSM, OR = 5.4) than in heterosexuals. Multivariate analyses showed a significant interaction between age and sexual preference. Subsequent stratified analyses by sexual preference showed a linear rise in coinfections with age in MSM. In heterosexuals, by contrast, bacterial coinfections peaked in those aged 19 or less; they had 27% of coinfections, while having only 14% of monodiagnoses and 10% of consultations. Heterosexual STD clinic attendees of Surinamese or Antillean origin were significantly at higher risk for coinfection (OR = 6.5) than all other ethnicities. CONCLUSIONS: Attendees belonging to specific sexual networks, such as MSM, ethnic groups, and young heterosexuals were at increased risk for STD coinfections. The different trend with age in MSM versus heterosexuals suggests that these 2 high-risk networks have different determinants of higher risk, such as age-related sexual risk-taking, biologic susceptibility, and insufficient knowledge or compliance with prevention measures. Prevention should therefore be targeted differently towards specific sexual networks.

Trends in sexually transmitted infections in the Netherlands, combining surveillance data from general practices and sexually transmitted infection centers.

BACKGROUND: Sexually transmitted infections (STI) care in the Netherlands is primarily provided by general practitioners (GPs) and specialized STI centers. STI surveillance is based on data from STI centers, which show increasing numbers of clients. Data from a GP morbidity surveillance network were used to investigate the distribution in the provision of STI care and the usefulness of GP data in surveillance. METHODS: Data on STI-related episodes and STI diagnoses based on ICPC codes and, for chlamydia, prescriptions, were obtained from GP electronic medical records (EMRs) of the GP network and compared to data from STI centers from 2002 to 2007. Incidence rates were estimated for the total population in the Netherlands. RESULTS: The incidence of STI-consultations and -diagnoses increased substantially in recent years, both at GPs and STI centers. The increase in consultations was larger than the increase in diagnoses; Chlamydia incidence rose especially at STI centers. GPs were responsible for 70% of STI-related episodes and 80-85% of STI diagnoses. STI centers attract relatively younger and more often male STI-patients than GPs. Symptomatic STIs like Herpes genitalis and genital warts were more frequently diagnosed at GPs and chlamydia, gonorrhea and syphilis at STI centers. CONCLUSIONS: GPs fulfill an important role in STI care, complementary to STI centers. Case definitions of STI could be improved, particularly by including laboratory results in EMRs. The contribution of primary care is often overlooked in STI health care. Including estimates from GP EMRs can improve the surveillance of STIs.

Sexual behaviour and STI testing among Dutch swingers: A cross-sectional internet based survey performed in 2011 and 2018.

BACKGROUND: Swingers, heterosexuals who, as couples, practice mate swapping or group sex with other couples or heterosexual singles, are at risk for sexually transmitted infections (STIs). Therefore, the aim of this study was to assess changes in sexual behaviour and STI testing behaviour, as well as predictors of STI testing. METHODS: Two cross-sectional studies were performed, using the same internet survey in 2011 and 2018. For trend analysis, sexual behaviour and STI testing behaviour were used. Socio-demographics, swinger characteristics, sexual behaviour, and psycho-social variables were used to assess predictors of STI testing in the past year, using multivariable regression analysis. RESULTS: A total of 1173 participants completed the survey in 2011, and 1005 in 2018. Condom use decreased for vaginal (73% vs. 60%), oral (5% vs. 2%), and anal sex (85% vs. 75%). STI positivity was reported in 23% and 30% of the participants, respectively, although testing for STI was comparable between both years (~65%). The following predictors of STI testing were significant: being female (OR = 1.9, 95%CI: 1.2-2.9), having a high swinging frequency (>12 times a year, OR = 3.7, 95%CI: 1.9-7.3), swinging at home (OR = 1.6, 95%CI: 1.0-2.7), receiving a partner notification (OR = 1.7, 95%CI: 1.2-2.6), considering STI testing important (OR = 4.3, 95%CI: 2.2-8.5), experiencing no pressure from a partner to test (OR = 0.6, 95%CI: 0.3-0.9), partners test for STI regularly (OR = 10.0, 95%CI: 6.2-15.9), perceiving STI testing as an obligation (OR = 2.1, 95%CI: 1.3-3.5), experiencing no barriers such as being afraid of testing (OR = 1.9, 95%CI: 1.2-3.1), limited opening hours (OR = 1.6, 95%CI: 1.0-2.4), and forgetting to plan appointments (OR = 3.0, 95%CI: 2.0-4.6). CONCLUSIONS: Swingers exhibit self-selection for STI testing based on their sexual behaviour. However, STI prevention efforts are still important considering the increasing numbers of reported STIs, the decreased use of condom use, and the one-third of swingers who were not tested in the previous year.

Determinants of frequent and infrequent STI testing and STI diagnosis related to test frequency among men who have sex with men in the eastern part of the Netherlands: a 6-year retrospective study.

OBJECTIVE: Men who have sex with men (MSM) remain vulnerable to sexually transmitted infections (STIs) and are advised to be tested at least twice a year. The aim of this study was to assess the determinants of test frequency and their associations with an STI diagnosis. DESIGN: A 6-year retrospective study. SETTING: 5 STI clinics in the eastern part of the Netherlands. PARTICIPANTS: MSM whose mean test interval was 6 months or more were grouped as 'infrequently tested' (n=953), and those with a mean test interval less than 6 months were grouped as 'frequently tested' (n=658). PRIMARY AND SECONDARY OUTCOME MEASURES: Test frequency and STI diagnosis and determinants. RESULTS: MSM who were ever diagnosed with an STI (OR=1.4, 95% CI 1.1 to 1.7), MSM who had never had STI symptoms (OR=0.8, 95% CI 0.6 to 1.0), and MSM who had ever had sex with both men and women (OR=0.6, 95% CI 0.5 to 0.8) were more often frequently tested. Moreover, in both groups, MSM who had ever been notified by a partner (OR=2.2, 95% CI 1.7 to 2.9 infrequently tested; OR=2.0, 95% CI 1.4 to 2.9 frequently tested), MSM who had ever had STI symptoms (OR=1.6, 95% CI 1.2 to 2.1 infrequently tested; OR=1.8, 95% CI 1.3 to 2.6 frequently tested) and MSM who were ever diagnosed with HIV (OR=2.7, 95% CI 1.5 to 4.6 infrequently tested; OR=6.8, 95% CI 2.6 to 17.5 frequently tested) were more likely to be diagnosed with an STI. CONCLUSIONS: Among MSM visiting STI clinics, those who were ever diagnosed with HIV were more often diagnosed with an STI, but did not visit STI clinics more frequently than HIV-negative MSM. This highlights the necessity of encouraging MSM who are diagnosed with HIV to have STI tests more frequently.

[More efficient testing policy at STI clinics]. / Doelmatiger testbeleid van soa-poliklinieken GGD.

OBJECTIVE: To assess the efficiency of the testing policy change in 2012 in sexually transmitted infection (STI) outpatient clinics: persons who attend the clinic and are aged < 25 years without other risk factors are initially tested only for chlamydia, and only in the event of a positive test result will they be tested for other STIs. Other possible changes in the STI testing policy were explored. DESIGN: Explorative study. METHOD: To test the new policy, data from STI outpatient clinics from 2011 were used for the risk group "young people under 25 years of age without other STI risks". Other groups who visited STI outpatient clinic were selected from the data from the STI outpatient clinics from 2012. Test cost savings and missed STIs were calculated if STI outpatient clinic attendees from these risk groups first received only a chlamydia or a combination test (chlamydia and gonorrhoea). Test cost savings were divided by the number of missed STIs as a measure of efficiency. RESULTS: The policy change led to an annual test cost saving of € 1.1 million but missed 31 gonorrhoea infections (€ 36,200 at the cost of one missed gonorrhoea infection). Using a combination test for chlamydia and gonorrhoea in heterosexual individuals visiting the clinic aged < 25 years and not from a STI-endemic country could lead to test costs savings of € 3.8 million. Savings at the cost of one missed STI would be about € 350,000; 4 HIV and 7 syphilis infections would have been missed. CONCLUSION: The national policy change has led to a substantial reduction in test costs. The policy measure would be even more efficient if a combination test for chlamydia and gonorrhoea were applied. Testing using a combination test in all heterosexual individuals who attend the clinic and are aged < 25 years and not from an STI-endemic country would lead to additional savings.

[Gonococci change more quickly than prescribing practices; resistance to frequently prescribed antibiotics]. / Gonokok wijzigt sneller dan voorschrijfgedrag: resistentie tegen veel voorgeschreven antibiotica.

Gonococcal resistance to antibiotics is increasing worldwide. In patients tested in Dutch STI clinics in 2009, gonococcal resistance to ciprofloxacin was over 50%. Ceftriaxone, a third-generation cephalosporin, has been the first-choice medication since 2004. General practitioners treated 25% of their gonorrhoea patients with ciprofloxacin in 2010. There is a need for up-to-the-minute, dynamic guidelines for treating gonorrhoea as well as the more systematic use of an up-to-date digital prescription system.

Improved tracing of hepatitis B virus transmission chains by phylogenetic analysis based on C region sequences.

An effective vaccine is available for the hepatitis B virus (HBV), which is a very contagious human pathogen. The prevalence of chronic HBV infection is very low in the Netherlands (<0.5%), and no universal vaccination is in place. Instead, a program of vaccination for targeted groups at high risk of HBV exposure has been implemented. Because transmission of HBV can occur by various routes, the effectiveness of this targeted vaccination strategy is difficult to assess. Molecular typing data for the surface protein encoding gene of HBV isolates, in combination with epidemiological data, provide some insight into the main transmission routes. Due to the low mutation rate of the HBV genome, many isolates have identical S region sequences, which hampers phylogenetic analysis and identification of transmission chains. The molecular epidemiological analysis of acute HBV isolates based on the surface and core protein encoding regions were compared. The nucleotide diversity found in the C region was statistically significant greater (1.5 times) than in the S region, and phylogenetic analysis based on the C region showed a higher resolution. C region analysis resulted in an almost 50% reduction of genotype A isolates with identical sequences. C region analysis also indicated that no long-chain transmission of genotype D strains is occurring in the Netherlands, as all genotype D isolates have unique C region sequences. Defining the goals of molecular typing of HBV isolates should precede the choice for phylogenetic analysis on the basis of either C or S region sequences.

Fat and K-ras mutations in sporadic colorectal cancer in The Netherlands Cohort Study.

Associations between dietary intake of various fats and specific K-ras mutations in colorectal cancer (CRC) were investigated within the framework of The Netherlands Cohort Study on diet and cancer (NLCS). After 7.3 years of follow-up and with exclusion of the first 2.3 years, 448 colon and 160 rectal cancer patients and 2948 subcohort members (55-69 years at baseline) were available for data-analyses. Mutation analysis of the K-ras gene was performed on all archival colon and rectal adenocarcinoma specimens. Case-cohort analyses were used to compute adjusted incidence rate ratios (RR) and 95% confidence intervals (CI) for colon and rectal cancer cases and for K-ras mutation subgroups. The intake of total, saturated and monounsaturated fat was not significantly associated with colon or rectal cancer. High intake of dietary polyunsaturated fat and, specifically, linoleic acid is associated with an increased risk of mutated K-ras colon tumours. The RRs for 1 SD of increase of polyunsaturated fat and linoleic acid were 1.21 (95% CI 1.05-1.41) and 1.22 (95% CI 1.05-1.42), respectively, and similar associations were observed for both G > A transitions and G > T or G > C transversions in the colon. In contrast, no significant associations were observed with rectal cancer risk, overall nor with specific K-ras mutation status. A high intake of polyunsaturated fat, in particular linoleic acid, may be an important dietary risk factor for K-ras mutated colon tumours, possibly by generating G > A transitions or G > T or G > C transversions in the K-ras oncogene.