Troy Grennan

Background: We compared the prevalence of vaccine-preventable anal human papillomavirus (HPV) types among gay, bisexual, and other men who have sex with men (GBM) living in large cities in Canada from 2019 to 2021 by age and human immunodeficiency virus (HIV) status. Methods: Sexually active GBM ≥16 years were recruited in Montreal, Toronto, and Vancouver using respondent-driven sampling (RDS). Participants self-reported HPV vaccination and self-collected anal HPV specimens. We estimated the prevalence of vaccine-preventable types for participants during the 2019–2021 period. We report RDS-II-weighted prevalence and confounder-adjusted prevalence ratios (aPRs) comparing vaccinated (≥1 dose) and unvaccinated GBM using multivariable Poisson regression. Results: Among 1519 participants aged 18–83 (median 35 years), 17.6% had HIV, and 62.2%, 40.2%, and 15.0% were vaccinated in the 16–26-, 27–45-, and ≥46-year groups, respectively. Among GBM 16–26 years, HPV6/11/16/18 prevalence was lower among those vaccinated ≤23 years (aPR = 0.40, 95% CI: .20–.77), ≥3 years since first dose (aPR = 0.39; 95% CI: .18–.85), and those with ≤5 years of sexual activity before vaccination (aPR = 0.47; 95% CI: .25–.89). HPV6/11/16/18/31/33/45/52/58 prevalence was lower among those vaccinated ≤26 years in GBM aged 27–45 years (aPR = 0.81, 95% CI, .61–1.08), though this did not reach statistical significance. Conclusions: Five years after implementation of Canadian HPV vaccination programs for younger GBM, anal HPV prevalence was lower among those vaccinated at younger ages and near sexual debut.

Objectives: Doxycycline as post-exposure prophylaxis (doxy-PEP) has emerged as an efficacious strategy to reduce Chlamydia trachomatis (C. trachomatis) , Neisseria gonorrhoeae (N. gonorrhoeae) and syphilis (sexually transmitted infections (STIs)) among gay, bisexual and other men who have sex with men (GBM). There is a need to identify prescribing criteria that maximise the number of STIs averted while minimising excessive use. Design: In this prospective longitudinal cohort study with repeated measures and biobehavioural data collection, participants completed a questionnaire and tested for STIs at each visit. Setting: Community-based, population-level study conducted in three large Canadian cities between February 2017 and July 2023. Participants: 2449 GBM were recruited through respondent-driven sampling (RDS); 1998 had ≥1 follow-up visit, contributing 7551 person-years of observation. Eligible participants were aged ≥16 years, cis- or transgender men, reported sex with another man in the past 6 months and resided in Montreal, Toronto or Vancouver. Primary and secondary outcome measures: Adjusted rate ratios (aRR) of STIs, accounting for RDS recruitment, loss to follow-up and confounding were estimated using generalised estimating equations (GEE) Poisson regression. For identified STI risk factors, the proportions of STIs averted through doxy-PEP prescription (based on the efficacy of doxy-PEP for each bacterial STI) and the number needed to treat (NNT) for 1 year to avert one STI, assuming 100% adherence, were calculated. Results: Among 1998 participants, the combined incidence rate of any C. trachomatis , N. gonorrhoeae and syphilis infection was 29.5 (95%CI 27.3 to 31.9) per 100 person-years. STI risk factors that had the most impact as doxy-PEP criteria were history of any of the three STIs in the past 12 months (P12M) (aRR=2.0, 95% CI 1.8 to 2.2, 36% STI averted, NNT=2.1); ≥10 male sexual partners in the past 6 months (P6M) (aRR=3.8, 95% CI 3.0 to 4.9, 41% STI averted, NNT=2.4); HIV-pre-exposure prophylaxis (PrEP) use P6M (aRR=1.7, 95% CI 1.5 to 2.0, 29% STI averted, NNT=2.5); use of any chemsex-related substance P6M (aRR=1.2, 95% CI 1.1 to 1.4, 28% STI averted, NNT=2.6); and group sex event attendance P6M (aRR=1.2, 95% CI 1.1 to 1.3, 27% STI averted, NNT=2.3). Reporting≥10 male sex partners P6M represented the most useful criterion for syphilis prevention (52% syphilis infections averted, NNT=20). Prescribing doxy-PEP to GBM having any of the following STI risk factors, namely, ≥1 bacterial STI P12M, ≥10 male sex partners P6M, or HIV-PrEP use P6M, would substantially increase the proportion of all STI diagnoses potentially averted (60%) with minimal increase of the NNT (2.7). Conclusion: This work informs on the impact of various doxy-PEP clinical prescribing criteria and demonstrates the benefit of focusing on any of the following three criteria: ≥1 bacterial STI P12M, ≥10 male sex partners P6M or HIV-PrEP use P6M.

Background: Anal squamous cell carcinoma caused by human papillomavirus disproportionately affects people living with human immunodeficiency virus (HIV; PLWH), particularly gay, bisexual, and other men who have sex with men (GBM). New guidelines recommend screening and treatment of precancerous lesions. We aimed to estimate anal cancer incidence by HIV status, sex, and GBM status in British Columbia, Canada. Methods: Using administrative health databases, we assessed anal cancer stratified by HIV status, sex, and sexual orientation from 1990 to 2019. A phenotypic algorithm was used to classify GBM status. We evaluated the comparative incidence of anal cancer using Fine and Gray’s competing risks subdistribution hazards model. Hazard ratios (HR) were estimated and adjusted for age, healthcare utilization, urbanicity, and Charlson comorbidity index. Results: Among 571 anal cancer diagnoses assessed, the incidence was highest among GBM with HIV [78.09 per 100,000 person-years (PY); 95% confidence interval (CI), 61.24–99.58], followed by heterosexual males with HIV (44.49 per 100,000 PY; 95% CI, 29.56–66.95) and females with HIV (12.05 per 100,000 PY; 95% CI, 4.52–32.11). GBM with HIV experience a 76-fold increased anal cancer risk compared with heterosexual men without HIV (adjusted HR 76.08; 95% CI, 55.14–104.97). Conclusions: There is an unmet need in anal cancer prevention among PLWH. Screening strategies that are sensitive, specific, acceptable, and cost-effective are necessary. Impact: This study provides the first population-based estimates of anal cancer incidence by HIV and GBM status in British Columbia, highlighting disparities and rising trends. These findings support prioritizing targeted screening programs and improving access to care.

Background: Digital technologies are reshaping health care, making digital health literacy (DHL) a critical competency for navigating online health information. Although widely conceived and measured as a unidimensional measure of DHL, the literature increasingly supports a multidimensional framing of the eHealth Literacy Scale (eHEALS). Studies propose alternative factor structures that can better inform population-level interventions, but these studies have not accounted for the ordinal nature of eHEALS response data. Objective: This study aimed to identify and validate an alternate multidimensional structure of eHEALS accounting for its ordinal response scale. Methods: Data were drawn from the 2022 GetCheckedOnline community survey of consenting English-speaking British Columbia residents aged ≥16 years who reported sexual activity in the past 12 months. Participants were recruited through geo-targeted digital advertisements, community outreach, and in-person recruitment at public events, and community locations. DHL was measured using eHEALS, with responses collected on a 5-point Likert scale. Descriptive statistics summarized eHEALS responses using means, medians, and IQRs. Exploratory and confirmatory factor analyses were used to assess the scale’s structure using polychoric correlations and standard model fit indices. Reliability and validity were evaluated using polychoric ordinal alpha, average variance extracted, and composite reliability, with missing data addressed via multiple imputation. Results: Overall, 1657 participants met inclusion criteria with a mean age of 33.0 (SD 11.77, 95% CI 32.4-33.6) years. Among these 47.3% (95% CI 44.9%-49.7%) identified as women, 30.4% (95% CI 28.1%-32.6%) identified as racialized minorities, 80.5% (95% CI 78.5%–82.3%) reported easy internet access, and 32.2% (95% CI 30.0%-34.5%) had a bachelor’s degree or higher. Across eHEALS items, median scores were 4.0 (IQR 1.0-2.0) with excellent internal consistency (polychoric ordinal α=.92). Exploratory factor analysis supported a 3-factor solution explaining 65.7% of the variance, demonstrated through confirmatory factor analysis (χ²17=71.7, P<.001, root-mean-square error of approximation=0.059, standardized root-mean-square residual=0.026, comparative fit index=0.969, Tucker-Lewis Index=0.948). The final model included Information Navigation (standardized loadings=0.765-0.917), Resource Appraisal (0.825-0.892), and Confidence in Use (0.803 for both items), with composite reliability (0.784-0.900), and average variance extracted (0.503-0.738) supporting construct validity. Conclusions: This study confirms a multidimensional structure of eHEALS, identifying Information Navigation, Resource Appraisal, and Confidence in Use as key dimensions of DHL. This revised model enhances measurement precision, enabling more accurate identification of populations with limited DHL and informing the development of targeted, equity-oriented interventions. Future research should aim to confirm this multidimensional structure in more diverse populations and explore how distinct DHL domains influence access to digital health services in various contexts. Additionally, ongoing scale development must adapt to account for the role of emerging technologies, including artificial intelligence and social media algorithms in health care.

Doxycycline pre-exposure prophylaxis (doxyPrEP) has shown potential in preventing bacterial sexually transmitted infections, but the impact on the microbiome is unknown. This study assessed rectal microbiome changes over 48 weeks in 41 participants on HIV PrEP (tenofovir disoproxil fumarate/emtricitabine) enrolled in an open-label, randomized pilot trial comparing immediate (100 mg PO daily started immediately and continued to week 48) versus deferred doxyPrEP (100 mg PO daily starting at week 24, continued to week 48) in HIV-negative gay and bisexual men (Clinical Trial #: NCT02844634). Primary study outcomes included feasibility, adherence, and tolerability of the dual PrEP regimen, while exploratory outcomes included rectal microbiome changes. We performed 16S rRNA sequencing from participants that collected baseline, week 24, and week 48 samples. Microbial composition did not significantly change over time in either study arm as measured by individual taxa levels, or alpha and beta diversity at the genus level. A slight decrease ( < 10%) in alpha diversity was observed at the phylum level in the immediate arm, but not the deferred arm. This study shows doxyPrEP use results in minimal compositional changes in the microbiome over 12 months. Further research is needed to explore the impact of doxycycline for STI prevention on microbiome function and antimicrobial resistance.

BACKGROUND Digital technologies are reshaping health care, making digital health literacy (DHL) a critical competency for navigating online health information. Although widely conceived and measured as a unidimensional measure of DHL, the literature increasingly supports a multidimensional framing of the eHealth Literacy Scale (eHEALS). Studies propose alternative factor structures that can better inform population-level interventions, but these studies have not accounted for the ordinal nature of eHEALS response data. OBJECTIVE This study aimed to identify and validate an alternate multidimensional structure of eHEALS accounting for its ordinal response scale. METHODS Data were drawn from the 2022 GetCheckedOnline community survey of consenting English-speaking British Columbia residents aged ≥16 years who reported sexual activity in the past 12 months. Participants were recruited through geo-targeted digital advertisements, community outreach, and in-person recruitment at public events, and community locations. DHL was measured using eHEALS, with responses collected on a 5-point Likert scale. Descriptive statistics summarized eHEALS responses using means, medians, and IQRs. Exploratory and confirmatory factor analyses were used to assess the scale’s structure using polychoric correlations and standard model fit indices. Reliability and validity were evaluated using polychoric ordinal alpha, average variance extracted, and composite reliability, with missing data addressed via multiple imputation. RESULTS Overall, 1657 participants met inclusion criteria with a mean age of 33.0 (SD 11.77, 95% CI 32.4-33.6) years. Among these 47.3% (95% CI 44.9%-49.7%) identified as women, 30.4% (95% CI 28.1%-32.6%) identified as racialized minorities, 80.5% (95% CI 78.5%–82.3%) reported easy internet access, and 32.2% (95% CI 30.0%-34.5%) had a bachelor’s degree or higher. Across eHEALS items, median scores were 4.0 (IQR 1.0-2.0) with excellent internal consistency (polychoric ordinal α=.92). Exploratory factor analysis supported a 3-factor solution explaining 65.7% of the variance, demonstrated through confirmatory factor analysis (χ²17=71.7, P<.001, root-mean-square error of approximation=0.059, standardized root-mean-square residual=0.026, comparative fit index=0.969, Tucker-Lewis Index=0.948). The final model included Information Navigation (standardized loadings=0.765-0.917), Resource Appraisal (0.825-0.892), and Confidence in Use (0.803 for both items), with composite reliability (0.784-0.900), and average variance extracted (0.503-0.738) supporting construct validity. CONCLUSIONS This study confirms a multidimensional structure of eHEALS, identifying Information Navigation, Resource Appraisal, and Confidence in Use as key dimensions of DHL. This revised model enhances measurement precision, enabling more accurate identification of populations with limited DHL and informing the development of targeted, equity-oriented interventions. Future research should aim to confirm this multidimensional structure in more diverse populations and explore how distinct DHL domains influence access to digital health services in various contexts. Additionally, ongoing scale development must adapt to account for the role of emerging technologies, including artificial intelligence and social media algorithms in health care.

Syphilis proctitis is a rare manifestation of syphilis, a bacterial sexually transmitted infection caused by Treponema pallidum. Syphilis proctitis can mimic other conditions including inflammatory bowel disease, lymphogranuloma venereum and anal or rectal cancer. We describe a case of a man in his 60s presenting with a variety of anorectal symptoms, where the definitive diagnosis was challenging, leading to diagnostic delay and a protracted symptom course due to difficulties in identifying and treating this rare manifestation of syphilis. After extensive investigations and various treatments, a diagnosis of syphilis was made, and treatment resulted in complete resolution of symptoms within 1 month. This case highlights several issues for clinicians to consider during the diagnostic workup and management of patients presenting with anal symptoms and, in the context of a global upsurge in syphilis, serves as a reminder to remain vigilant to unusual and rare manifestations of infectious syphilis.

Background: Men who have sex with men (MSM) and transgender women experience high sexually transmitted infection (STI) rates. This study evaluated the feasibility of doxycycline pre-exposure prophylaxis (doxyPrEP) for STI prevention in these key populations. Methods: Sexually-active MSM and transgender women without human immunodeficiency virus (HIV) with prior syphilis were recruited. Participants initiated HIV PrEP with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) daily for 48 weeks and were randomized 1:1 to daily doxyPrEP for 48 weeks (immediate arm), or doxyPrEP initiated at 24 weeks (deferred arm). Primary outcomes included adherence, measured using questionnaires, along with tolerability; STI incidence (chlamydia, gonorrhea, syphilis) was a secondary outcome. Nasal carriage of Staphylococccus aureus was assessed serially for doxycycline resistance. Results: Fifty-two participants were enrolled into the immediate (n = 26) and deferred (n = 26) arms. At 48 weeks, self-reported adherence (≥95%) was 75.0% versus 66.7% (P = .538) for TDF/FTC, and 70.8% versus 61.9% (P = .526) for doxycycline in the immediate versus deferred arms, respectively. No doxyPrEP-related serious adverse events occurred. Incidence of any STI at 24 weeks was reduced in the immediate versus deferred arms, and over 48 weeks, being on doxycycline (vs being off; ie, first 24 weeks of deferred arm) was associated with STI reduction (adjusted odds ratio [aOR] 0.36; 95% confidence interval [CI]: .15–.89). Emergent doxycycline-resistant S. aureus was identified in six individuals, with five in the immediate arm (P = .077). Conclusions: Dual HIV/doxyPrEP is feasible and associated with a significant reduction in incident STI. Further evaluation of dosing strategies, efficacy and impact on antimicrobial resistance is warranted.