NMR Coupling Constants, Karplus Equations, and Adjusted MD Statistics: Detecting Diagnostic Torsion Angles for the Solution Geometry of 6-[α-d-Mannopyranosyl]-d-Mannopyranose (Mannobiose).

The quantitative solution conformations of 2-(hydroxymethyl)-tetrahydropyran, α-methyl-d-mannopyranoside, and 6-[α-d-mannopyranosyl]-d-mannopyranose (mannobiose) are described. Parametrized Karplus equations for redundant spin pairs across the terminal ω-torsion and the glycosidic ω-torsion for mannobiose are developed, including ω/θ-hypersurfaces for the terminal hydroxymethylene group. Experimental NMR data, algorithmic spectral simulation (clustered Hamiltonian method), molecular dynamics (MD) simulations (GLYCAM06), energy minimizations by DFT, and adjusted torsion angle populations weighted over the Karplus-type equations are used. We demonstrate that spectral simulation is a powerful tool in the refinement of initial J values obtained from static GAIO DFT calculations. We also show that only as few as one of multiple redundant torsions can be diagnostic for conformational analysis of the disaccharide.

The incubation for urethral gonorrhoea among men who have sex with men with and without oropharyngeal gonorrhoea.

We hypothesized that the incubation for urethral gonorrhoea would be longer for men with oropharyngeal gonorrhoea than those without oropharyngeal gonorrhoea. We conducted a chart review of men who have sex with men with urethral gonorrhoea symptoms at a sexual health clinic between 2019 and 2021. The incubation period was defined as the number of days between men's last sexual contact and onset of symptoms. We used a Mann-Whitney U test to compare differences in the median incubation for urethral gonorrhoea between men with and men without oropharyngeal gonorrhoea. There were 338 men with urethral symptoms (median age = 32 years; IQR: 28-39), and of these, 307 (90.1%) were tested for oropharyngeal gonorrhoea, of whom 124 (40.4%, 95% CI: 34.9-46.1) men had oropharyngeal and urethral gonorrhoea. We analyzed incubation data available for 190 (61.9%) of the 307 men, with 38.9% (74/190) testing positive for oropharyngeal gonorrhoea. The incubation for urethral gonorrhoea did not differ between 74 men (39%) with oropharyngeal gonorrhoea (median = 4 days; IQR: 2-6) and 116 men (61%) without oropharyngeal gonorrhoea (median = 2.5 days; IQR: 1-5) (p = 0.092). Research is needed to investigate gonorrhoea transmission from the oropharynx to the urethra.

Association between saliva use for masturbation and urethral gonorrhoea in men who have sex with men: A cross-sectional study.

OBJECTIVES: The saliva of individuals with oropharyngeal gonorrhoea can contain viable Neisseria gonorrhoeae. This study examined if using saliva as a lubricant for masturbation is a risk factor for urethral gonorrhoea among men who have sex with men (MSM). METHODS: In this cross-sectional study, MSM aged ≥18 years attending the Melbourne Sexual Health Centre between February 2021 and December 2023 were surveyed. Data were collected on sexual activities in the past 7 days, including receiving fellatio, condomless insertive anal sex, docking, and using saliva for masturbation. Multivariable logistic regression examined associations between these exposures and urethral gonorrhoea. RESULTS: The median age of the 3114 men was 32 (IQR: 27-40), with 4.7% (n = 145) testing positive for urethral gonorrhoea. Urethral gonorrhoea was independently associated with an increasing number of partners for condomless insertive anal sex (P < 0.001). It was not significantly associated with receiving fellatio (P = 0.613), docking (P = 0.207), or using saliva for masturbation (P = 0.117). However, of the 110 men who only used saliva for masturbation, two (1.8%) had urethral gonorrhoea, and one (0.9%) had both urethral and oropharyngeal gonorrhoea. CONCLUSION: Condomless insertive anal sex is the leading risk factor for urethral gonorrhoea and not using saliva as a lubricant for masturbation.

Changes in HIV post-exposure prophylaxis prescriptions before and after the introduction of HIV pre-exposure prophylaxis at a sexual health clinic in Melbourne, Australia, 2011-2021.

OBJECTIVE: HIV pre-exposure prophylaxis (PrEP) became available in Victoria, Australia, in 2016. We examined non-occupational post-exposure prophylaxis (nPEP) usage among gay, bisexual and other men who have sex with men (MSM) before and after PrEP became available. METHODS: We included MSM attending Melbourne Sexual Health Centre for nPEP between 2011 and 2021. We analysed three periods: the 'pre-PrEP' (01 Jan 2011 to 25 Jul 2016), 'PrEP before COVID-19' (26 Jul 2016 to 31 Dec 2019), and 'PrEP during COVID-19' (01 Jan 2020 to 31 Dec 2021). RESULTS: There were 222,978 consultations for MSM; 8292 (3.7%) were nPEP consultations. The proportion of nPEP consultations increased from 3.3% (3093/94263) in the pre-PrEP period to 4.3% (3843/89251) in the PrEP before COVID-19 period then dropped to 3.4% (1356/39464) during the COVID-19 period. Compared to Australian-born MSM, MSM born in Central/South America (adjusted odds ratio [aOR]: 1.75; 95% confidence interval [CI]: 1.27-2.40) had the highest odds of accessing nPEP, followed by Asian-born MSM (aOR: 1.47; 95% CI: 1.27-1.71) after adjusting for PrEP availability and COVID-19. Those newly arrived in Australia in ≤4 years had higher odds (aOR: 1.14; 95% CI: 1.05-1.22) of accessing nPEP than those living in Australia for >4 years. CONCLUSION: nPEP prescriptions declined with PrEP availability. Newly arrived overseas-born MSM who are unlikely to have access to subsidised PrEP have a higher demand of nPEP. IMPLICATIONS FOR PUBLIC HEALTH: Increasing PrEP education and ensuring equal access is vital in the drive to reduce new HIV diagnoses.

Increased syphilis testing and detection of late latent syphilis among women after switching from risk-based to opt-out testing strategy in an urban Australian sexual health clinic: a retrospective observational study.

Background: The Melbourne Sexual Health Centre (MSHC) implemented an opt-out syphilis test for women in December 2017. We aimed to examine the differences in syphilis testing uptake and confirmed syphilis cases among women after switching from risk-based to opt-out testing strategies. Methods: This was a retrospective study examining all women attending the MSHC for the first time in periods of risk-based testing (2015-2017) and opt-out testing (2018-2020). We calculated the proportion of women who tested for syphilis and the proportion of women with confirmed syphilis in each period. A chi-square test was performed to determine the differences in proportion between the risk-based testing and opt-out periods. Findings: A total of 27,481 women (i.e. 13,059 in the risk-based testing period and 14,422 in the opt-out period) were included in the final analysis, and the mean age was 26.8 years (standard deviation = 6.9). The proportion of women who were tested for syphilis at their first consultation increased from 52.8% (6890/13,059) in the risk-based testing period to 67.4% (9725/14,422) in the opt-out period (p < 0.0001). Syphilis positivity did not differ between the two periods (0.48% [33/6890] vs 0.71% [69/9725], p = 0.061) but late latent causes increased from 36.4% [12/33] to 60.9% [42/69] (p = 0.033). Interpretation: The opt-out testing strategy increased syphilis testing among women with increased detection of asymptomatic late latent syphilis. The opt-out syphilis testing strategy is beneficial in sexual health services. Health education and awareness may be required to improve syphilis testing uptake. Funding: National Health and Medical Research Council.

Treponema pallidum PCR screening at mucosal sites of asymptomatic men who have sex with men taking HIV pre-exposure prophylaxis.

Early detection and treatment of syphilis will reduce the infectious period and transmission. We aimed to determine whether screening men who have sex with men (MSM) taking HIV pre-exposure prophylaxis (PrEP) for syphilis using Treponema pallidum polymerase chain reaction (PCR) could detect syphilis before the appearance of syphilis antibodies in serology. MSM attending 3-monthly PrEP clinic visits in Melbourne, Australia, were screened with a PCR assay targeting the polA gene of T. pallidum from an anal swab and an oral rinse between November 2019 and March 2020. Participants were serologically screened for syphilis using chemiluminescence immunoassay. A total of 309 asymptomatic participants provided an anal swab and oral rinse sample for T. pallidum PCR screening. Two syphilis cases (0.6%) were detected: one man had a positive serology only; another man had T. pallidum detected by PCR from an anal swab and a positive serology. PCR positivity was 0.3% (n = 1) for anal swabs and 0% (n = 0) for oral rinse. In this study, T. pallidum PCR screening at routine PrEP clinic visits did not identify additional cases of early syphilis over serological screening performed at these visits. IMPORTANCE With the ongoing syphilis epidemic in men who have sex with men (MSM), we investigated the role of using Treponema pallidum polymerase chain reaction (PCR) testing at the oral cavity and anus in MSM taking pre-exposure prophylaxis for the early detection of syphilis. We evaluated whether the PCR tests from these mucosal sites can detect syphilis infection early, before the development of syphilis antibodies in serology. Our study found two syphilis cases among 309 MSM, and only one syphilis case had a positive anal PCR swab, although serology was positive. We conclude that additional PCR testing is likely to be expensive and would not be cost effective for individuals who regularly screen for syphilis. However, future studies with a larger sample size are required.

Treponema pallidum Detection at Asymptomatic Oral, Anal, and Vaginal Sites in Adults Reporting Sexual Contact with Persons with Syphilis.

We investigated Treponema pallidum PCR positivity at mucosal sites (oral, anal, and vaginal sites) among adults who had sexual contact with a person with syphilis (syphilis contacts). All syphilis contacts had oral rinse and swab samples collected for testing. Men who have sex with men had anal swab and women had vaginal swab samples collected for testing, regardless of the presence of lesions. Of 407 persons tested, 42 (10%) had early syphilis diagnosed; of those, 19 (45%) tested positive by PCR from any anatomic site and had a positive serologic test. T. pallidum was positive from vaginal samples in 3 women, anal samples in 3 men, and oral cavity samples in 2 women and 3 men, without symptoms at those sites. Three women had no prior syphilis serologic test. T. pallidum detection at asymptomatic mucosal sites suggests early syphilis infections, particularly in cases that would conventionally be staged as latent syphilis of unknown duration.

Combinations of Sexual Activities During a Sex Episode with Recent Casual Male Partner Among Men Who Have Sex with Men: A Cross-Sectional Study.

We examined combinations of nine sexual activities that occurred during a sex episode with a recent male partner among men who have sex with men (MSM) who attended an urban sexual health clinic from April-2017 to September-2017. We collected the following sexual activities: tongue-kissing, penises touching, using saliva during mutual masturbation, performed rimming, received rimming, performed fellatio, received fellatio, insertive anal sex, and receptive anal sex. During a single-sex episode, the most common combinations of sexual activities involved all nine activities (10.6%, 166/1542). We assessed the agreement between any two sexual activities that occurred together during a sex episode. Agreement was highest for receiving rimming and receptive anal sex (kappa = 0.40; 95% CI: 0.35, 0.45), and performing rimming and insertive anal sex (kappa = 0.38; 95% CI: 0.33, 0.42). Agreement was lowest for insertive anal sex and receiving fellatio (kappa = -0.01; 95% CI: -0.05, 0.03), and receptive anal sex and insertive anal sex (kappa = -0.08; 95% CI: -0.13, 0.03). The sexual activities that occur between men are correlated with one another and this will influence transmission between anatomical sites.

Incidence and Risk Factors for Early Syphilis Among Men Who Have Sex With Men in Australia, 2013-2019: A Retrospective Cohort Study.

Background: We aimed to examine the incidence of syphilis in men who have sex with men (MSM) and identify subgroups of MSM at a higher risk of syphilis infection. Methods: We conducted a retrospective cohort study of MSM attending a sexual health clinic in Australia, during 2013-2019, who had at least 2 syphilis serological tests during the study period. The incidence of syphilis was expressed as per 100 person-years. A cox regression analysis was conducted to identify risk factors for syphilis. Results: A total of 24 391 individual MSM (75 086 consultations) were included. A total of 1404 new syphilis cases were diagnosed with an incidence of 3.7/100 person-years (95% confidence interval, 3.5-3.9). Syphilis incidence was higher in MSM with human immunodeficiency virus ([HIV] 9.3/100 person-years) than in MSM taking HIV pre-exposure prophylaxis (PrEP) (6.9/100 person-years) or HIV-negative MSM not taking PrEP (2.2/100 person-years). Risk factors associated with high incidence of syphilis included the following: MSM with HIV (adjusted hazard ratio [aHR] 2.7), MSM taking HIV PrEP (aHR 2.1), past history of syphilis infection (aHR 2.4), injecting drug use (aHR 2.7), condomless anal sex (aHR 1.7), >4 sexual partners in the last 12 months (aHR 1.2), and concurrent sexually transmitted infection (chlamydia and gonorrhoea) (aHR 1.6). Conclusions: The incidence of syphilis remains high among MSM, particularly in subgroups with associated risk factors for syphilis infections. These data highlight the need for biomedical and behavioral interventions to be targeted to subgroups of MSM at the highest risk of syphilis infection.

Assortative Sexual Mixing by Age, Region of Birth, and Time of Arrival in Male-Female Partnerships in Melbourne, Australia.

BACKGROUND: Patterns of sexual mixing may be influenced by demographic factors where individuals show a preference for partners with particular traits and may have different levels of risk for HIV and sexually transmitted infection transmission. We aimed to explore age differences and mixing by region of birth among male-female partnerships. METHODS: Male-female partnerships who presented to Melbourne Sexual Health Centre in Australia between 2015 and 2019 were investigated. Age and country of birth of sexual partners were collected. We calculated the age differences between partners and created tables demonstrating partnership mixing by age groups and by international region of birth. RESULTS: A total of 2112 male-female partnerships (i.e., 4224 individuals) were included. The median age was 27 years (interquartile range, 23-31 years). Between men and women in partnerships, the median age difference was 1 year. Nearly half of all individuals (49.1% [2072 of 4224]) were in a partnership with another individual in the same 5-year interval age group as their own, and a majority of individuals (58.5% [2334 of 3988]) were in a partnership with another individual from the same region of birth when compared with other regions. CONCLUSIONS: There is a strong assortative sexual mixing pattern by age and region of birth among male-female partnerships in Melbourne, Australia. These results may have applications in further research to understand sexually transmitted infection transmission among clients attending sexual health centers, particularly those born overseas.

Sexual activities and condom use among heterosexual men and women engaged in mixed-gender group sex events in Melbourne, Australia.

BACKGROUND: Few studies investigate group sex among heterosexuals. The aim of this study was to provide an exploration of characteristics and practices among heterosexual men and women who engage in group sex. METHOD: We conducted a cross-sectional survey between May 2019 and March 2020 among heterosexual men and women attending a sexual health clinic in Melbourne, Australia. Participants were asked whether they had participated in group sex (sex involving more than two participants) in the past 3months, the size of the most recent event, sexual activities in which they engaged, and condom use. RESULTS: Of 3277 heterosexuals surveyed (1509 women and 1768 men), the mean age was 29.9years (s.d. 8.8) and more than half (56.0%, n =1834) were born outside Australia. One in 20 participants (5.4%) had engaged in group sex in the past 3months with the number of events ranging 1-10times. Kissing was the most common activity in group sex, and women were significantly more likely to kiss a same-sex partner than men. Overall, of 165 participants who engaged in vaginal sex, 57 (34.5%) reported always using condoms and changing condoms between consecutive partners. Of the 100 men and women who had condomless vaginal sex, 79 (79.0%) received or performed fellatio after condomless vaginal sex. CONCLUSION: About two-thirds of heterosexuals who engaged in group sex neither used condoms nor changed condoms between partners in the most recent group sex event. Safe sex messages on changing condoms between partners and between sexual activities should be reinforced for sexually transmitted infections prevention.

Changes in the Syphilis Rapid Plasma Reagin Titer Between Diagnosis and Treatment.

BACKGROUND: We compared the rapid plasma reagin (RPR) titer on the day of initial presentation with that on the day of syphilis treatment to inform clinical practice as to whether a repeated RPR test should be recommended. METHODS: We undertook a retrospective study between 1 March 2011 and 31 December 2020 at the Melbourne Sexual Health Centre in Australia among individuals who underwent syphilis serology on the day of initial presentation and the day of treatment, if the latter were within 14 days after initial presentation. We calculated the percentage of individuals with a ≥4-fold change in RPR titer, stratified by the time between initial presentation and treatment and by syphilis stage. RESULTS: Among the 766 included syphilis cases, the median duration between initial presentation and treatment was 6 days (interquartile range, 5-7 days). Of these cases, 14.8% (n = 113) had a ≥4-fold increase or decrease during this interval. The number of cases with a ≥4-fold increase or decrease in RPR titer increased with increasing time between initial presentation and treatment, from 5.7% (n = 6) 1-3 days after initial presentation to 26.2% (n = 27) at 10-14 days (Ptrend < .001). There was no significant difference in the number of cases with a ≥4-fold increase or decrease in RPR titer between syphilis stages (P = .66). CONCLUSIONS: Our data support the recommendation of repeating the RPR titer if the day of initial presentation and the day of treatment are different, even when treatment is within a few days after initial presentation.

Non-conventional interventions to prevent gonorrhea or syphilis among men who have sex with men: A scoping review.

Objectives: We assessed nonconventional interventions that did not traditionally focus on increasing condom use and/or testing among men who have sex with men (MSM) and the evidence for these interventions. Methods: Guided by the Participants, Concept and Context (PCC) framework, we searched five online databases from inception to 9 August 2021 for original research on interventions that do not focus on increasing condom use and/or testing to prevent gonorrhea and/or syphilis in MSM. Two researchers screened titles and abstracts to assess eligibility, reviewed articles' full text and resolved discrepancies through discussion. We charted relevant study information, and the included studies were critically appraised. Results: Of 373 articles retrieved, 13 studies were included. These studies were conducted in Australia (n = 3), Belgium (n = 2), China (n = 3), the Netherlands (n = 1) and the US (n = 4). Two randomized controlled trials (RCTs) of doxycycline as pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) reduced any STI incidence (gonorrhea, syphilis, or chlamydia), but only doxycycline PEP significantly reduced syphilis incidence. Six studies of interventions that facilitated self-collection, self-examination, and self-testing, found varied evidence for gonorrhea and/or syphilis prevention. Four RCTs and one single-arm trial examined the efficacy of mouthwash, but the evidence remains inconclusive on whether mouthwash use can prevent transmission between men. Conclusion: We found evidence for doxycycline PEP in reducing syphilis incidence, evidence on the use of mouthwash to prevent gonorrhea transmission between men remains inconclusive. More evidence is needed for interventions that do not focus on increasing condom use and/or testing to prevent gonorrhea and/or syphilis.

Adherence to weekly anal self-examination among men who have sex with men for detection of anal syphilis.

Background: Men who have sex with men (MSM) practicing exclusively receptive anal sex are more likely to present with secondary than primary syphilis, implying primary anorectal lesions may be missed. If men could detect anorectal lesions by regular anal self-examination, the duration of infectiousness could be reduced. This study aimed to examine adherence to weekly anal self-examination. Method: We conducted a longitudinal feasibility study examining the adherence to weekly anal self-examinations among MSM attending a sexual health clinic in Melbourne, Australia between December 2020 and June 2021. Adherence to weekly anal self-examinations over 12 weeks was assessed from a logbook and 4-weekly surveys. Participants who identified abnormalities in their anus were recommended to seek medical review. Results: Of the 30 men who completed the study, anal self-examination was performed at least weekly for 308 of 360 person-weeks (86% of the weeks, 95% CI: 82-89). The mean adherence was 3.6 (95% CI: 3.3-3.9) examinations per 4-weeks per person in Weeks 1-4, 3.5 (95% CI: 3.1-3.8) in Weeks 5-8 and 3.3 (95% CI: 2.9-3.7) in Weeks 9-12 (P trend = 0.06). Six men (20%, 6/30) were seen for medical review after they identified abnormalities, whilst eight men (27%, 8/30) reported abnormalities, but did not seek medical review. No participants were diagnosed with syphilis during the study period. Conclusion: We conclude that men adhered well to weekly anal self-examination. Therefore, it is feasible to trial this as a routine practice among MSM. Future studies should investigate possible reductions in adherence over time and ways to increase medical review for abnormalities that men find.

Kissing, fellatio, and analingus as risk factors for oropharyngeal gonorrhoea in men who have sex with men: A cross-sectional study.

Background: Our aim was to determine whether exposure to the anatomical sites (oropharynx, penis, or anus) of male partners of men who have sex with men (MSM) were independent risk factors for oropharyngeal gonorrhoea after adjusting for exposures to these sites. Methods: In this cross-sectional study, we invited MSM who attended the Melbourne Sexual Health Centre (MSHC) in Victoria, Australia between 26-November 2018 and 31-December 2020 to complete a survey of their sexual practices in the past three months. We collected data on the number of male partners with whom men engaged in sexual activities that exposed their oropharynx to their partners' oropharynx (kissing), penis (fellatio), and anus (rimming or analingus). Only men who were aged ≥16 years, tested for oropharyngeal gonorrhoea and did not have indeterminate or invalid results were included in the final analysis. We conducted univariable and multivariable logistic regression analyses to investigate associations between oropharyngeal gonorrhoea and the three exposures to the oropharynx. Findings: The median age of the 2,322 men who completed the survey was 31 years (IQR: 26-40), and 5·2% (n = 120) were diagnosed with oropharyngeal gonorrhoea. Our univariate analysis showed that oropharyngeal gonorrhoea was significantly associated with increasing number of kissing (p trend<0·0001), rimming (p trend<0·0001) and fellatio (p trend<0·0001) partners. After adjusting for all three exposures, oropharyngeal gonorrhoea was associated with increasing number of kissing (p trend =0·014) and rimming partners (p trend = 0·037) but not fellatio (p trend = 0·61). Interpretation: Our data suggest kissing and rimming are important practices in oropharyngeal gonorrhoea transmission in MSM Novel interventions which target the oropharynx are required for gonorrohoea prevention. Funding: Australian National Health and Medical Research Council.

Exploring the Use of "Nudges" to Improve HIV and Other Sexually Transmitted Infection Testing Among Men Who Have Sex with Men.

Behavioral economics and its applied branch "nudging" can improve individual choices in various health care settings. However, there is a paucity of research using nudges to improve regular testing for HIV and other sexually transmitted infections (STIs). The study examined which reminder system and message type men who have sex with men (MSM) preferred to remind them to undergo regular 3-monthly HIV and STI testing. A cross-sectional survey study was conducted among MSM attending a sexual health clinic in Melbourne, Australia between 13 January and 5 March 2020, exploring the preferred method of reminder and framing of the message. Descriptive statistics and logistic regression were used to analyze the data. A total of 309 responses were received. The majority of the participants (90%) preferred short messaging service (SMS) as the reminder method for HIV/STI testing compared to other types (e.g., email or instant messaging). More than a third of the participants (45%) showed a preference for a neutrally framed reminder message (Your next check-up is now due. Please phone for an appointment), while one-third (35%) preferred a personalized message (Hi [first name], you are due for your next check-up. Please phone for an appointment). Younger men were more likely to favor positive framed messages than older men who favored neutrally framed messages (p < .01). SMS was the preferred reminder method for regular HIV/STI testing. Reminder messages that were neutrally framed, personalized or positive framed messages were preferred over negative or social norm messages.

Human papillomavirus vaccine coverage in male-male partnerships attending a sexual health clinic in Melbourne, Australia.

We aimed to investigate the sexual mixing by human papillomavirus (HPV) vaccination status in male-male partnerships and estimate the proportion of male-male partnerships protected against HPV. We analyzed male-male partnerships attending the Melbourne Sexual Health Center between 2018 and 2019. Data on self-reported HPV vaccination status were collected. Newman's assortativity coefficient was used to examine the sexual mixing by HPV vaccination status. Assortativity refers to the tendency of individuals to have partners with similar characteristics (i.e. same vaccination status). Of 321 male-male partnerships where both men reported their HPV vaccination status, 52.6% (95% CI: 47.0-58.2%) partnerships had both men vaccinated, 32.1% (95% CI: 27.0-37.5%) partnerships had only one man vaccinated, and 15.3% (95% CI: 11.5-19.7%) had both men unvaccinated. The assortativity on HPV vaccination status was moderate (assortativity coefficient = 0.265, 95% CI: 0.196-0.335). There were about 15% of male-male partnerships where both men were not protected against HPV. Interventions targeting vaccinated individuals to encourage their unvaccinated partners to be vaccinated might increase the HPV vaccine coverage.

Using machine learning approaches to predict timely clinic attendance and the uptake of HIV/STI testing post clinic reminder messages.

Timely and regular testing for HIV and sexually transmitted infections (STI) is important for controlling HIV and STI (HIV/STI) among men who have sex with men (MSM). We established multiple machine learning models (e.g., logistic regression, lasso regression, ridge regression, elastic net regression, support vector machine, k-nearest neighbour, naïve bayes, random forest, gradient boosting machine, XGBoost, and multi-layer perceptron) to predict timely (i.e., within 30 days) clinic attendance and HIV/STI testing uptake after receiving a reminder message via short message service (SMS) or email). Our study used 3044 clinic consultations among MSM within 12 months after receiving an email or SMS reminder at the Melbourne Sexual Health Centre between April 11, 2019, and April 30, 2020. About 29.5% [899/3044] were timely clinic attendance post reminder messages, and 84.6% [761/899] had HIV/STI testing. The XGBoost model performed best in predicting timely clinic attendance [mean [SD] AUC 62.8% (3.2%); F1 score 70.8% (1.2%)]. The elastic net regression model performed best in predicting HIV/STI testing within 30 days [AUC 82.7% (6.3%); F1 score 85.3% (1.8%)]. The machine learning approach is helpful in predicting timely clinic attendance and HIV/STI re-testing. Our predictive models could be incorporated into clinic websites to inform sexual health care or follow-up service.

A cross-sectional survey on attitudes of men who have sex with men towards anal self-examination for detection of anal syphilis.

Studies suggest men who have sex with men (MSM) practising receptive anal sex are more likely to present with secondary syphilis, implying primary anorectal lesions are likely to be missed. If men could detect anorectal lesions in the primary stage by regular anal self-examination (ASE), transmission could be reduced by early diagnosis and treatment. We aimed to explore the attitudes of MSM on performing ASE to detect primary anorectal syphilis. An online anonymous cross-sectional survey among MSM over 18 years of age living in Australia, was conducted between July and November 2020 and recruitment was from a sexual health clinic and social media. A total of 568 MSM completed the survey (median age: 34 [IQR 27-45]): 32% (183) had previously performed ASE. Among 66% (374) who had never performed ASE, 68% (250) would consider performing ASE in the future with a preferred median frequency of 2 times per 4 weeks (IQR 1-4), whilst men who were already performing ASE were performing it at median 1 per 4 weeks (IQR 0.2-3). Almost two-thirds of MSM who had never performed ASE were willing to adopt ASE practice in the future. Studies are required to determine the effectiveness of ASE for syphilis detection.