Discordance in chromosomal and self-reported sex in the UK Biobank: Implications for transgender- and intersex-inclusive data collection.

There is growing need to distinguish between sex and gender. While sex is assigned at birth, gender is socially constructed and may not correspond to one's assigned sex. However, in most research studies, sex or gender is assessed in isolation or the terms are used interchangeably, which has implications for research accuracy and inclusivity. We used data from the UK Biobank to quantify the prevalence of disagreement between chromosomal and self-reported sex and identify potential reasons for discordance. Among approximately 200 individuals with sex discordance, 71% of discordances were potentially explained by the presence of intersex traits or transgender identity. The findings indicate that when describing sex- and/or gender-specific differences in health, researchers may be limited in their ability to draw conclusions regarding specific sex and/or gender health information.

Gender-Affirming Care of Transgender and Gender-Diverse Youth: Current Concepts.

Increasing numbers of transgender and gender-diverse (TGD) youth, from early puberty through late adolescence, are seeking medical services to bring their physical sex characteristics into alignment with their gender identity-their inner sense of self as male or female or elsewhere on the gender spectrum. Numerous studies, primarily of short- and medium-term duration (up to 6 years), demonstrate the clearly beneficial-even lifesaving-mental health impact of gender-affirming medical care in TGD youth. However, there are significant gaps in knowledge and challenges to such care. Long-term safety and efficacy studies are needed to optimize medical care for TGD youth.

Update in Adult Transgender Medicine.

Transgender people often face barriers in health care due to lack of access to care, lack of knowledgeable healthcare professionals, discrimination, and gaps in medical and mental health research. Existing research on transgender health has focused heavily on mental health, HIV/AIDS, sexually transmitted diseases/infections, and substance abuse. Gender-affirming hormone therapy and/or surgery allows for some alignment of biology and gender identity. Gender-affirming care may offer quality-of-life benefits, which may outweigh modest concerns related to exogenous hormone therapy. The Endocrine Society treatment guidelines were revised in 2017, and this article reviews recent data that might inform a future guideline revision. Future longitudinal research is needed to close the gap in knowledge in the field of transgender medicine.

Androgenic steroids induce pathologic scarring in a preclinical porcine model via dysfunctional extracellular matrix deposition.

Hypertrophic scarring is a major source of morbidity. Sex hormones are not classically considered modulators of scarring. However, based on increased frequency of hypertrophic scarring in patients on testosterone, we hypothesized that androgenic steroids induce abnormal scarring and developed a preclinical porcine model to explore these effects. Mini-swine underwent castration, received no testosterone (noT) or biweekly testosterone therapy (+T), and underwent excisional wounding. To create a delayed wound healing model, a subset of wounds were re-excised at 2 weeks. Scars from postoperative day 42 (POD42) and delayed wounds (POD28) were harvested 6 weeks after initial wounding for analysis via histology, bulk RNA-seq, and mechanical testing. Histologic analysis of scars from +T animals showed increased mean fibrosis area (16 mm2noT, 28 mm2+T; p = .007) and thickness (0.246 mm2noT, 0.406 mm2+T; p < .001) compared to noT. XX+T and XY+T scars had greater tensile burst strength (p = .024 and p = .013, respectively) compared to noT swine. Color deconvolution analysis revealed greater deposition of type I and type III collagen as well as increased collagen type I:III ratio in +T scars. Dermatopathologist histology scoring showed that +T exposure was associated with worse overall scarring (p < .05). Gene ontology analysis found that testosterone exposure was associated with upregulation of cellular metabolism and immune response gene sets, while testosterone upregulated pathways related to keratinization and laminin formation on pathway analysis. In conclusion, we developed a preclinical porcine model to study the effects of the sex hormone testosterone on scarring. Testosterone induces increased scar tissue deposition and appears to increase physical strength of scars via supraphysiologic deposition of collagen and other ECM factors. The increased burst strength seen in both XX and XY animals suggests that hormone administration has a strong influence on scar mechanical properties independent of chromosomal sex. Anti-androgen topical therapies may be a promising future area of research.

Syphilis Prevalence, Incidence, and Demographic Differences in a Longitudinal Study of Young Sexual and Gender Minority Adults Assigned Male at Birth.

BACKGROUND: Syphilis rates in the United States have increased. Few studies have examined syphilis incidence and prevalence prospectively among young sexual and gender minorities (YSGM). METHODS: This study of YSGM assigned male at birth comes from a Chicago-based prospective cohort at 2 visits 6 months apart (N = 882). Syphilis cases were identified through serologic test results and self-reported history. RESULTS: In this sample, 25.1% had a lifetime prevalence, and 3.3% were incident cases with a crude incidence rate of 6.76 per 100 person-years. CONCLUSIONS: Lifetime syphilis and incidence are high in this sample of YSGM relative to general population samples.

Prevalence of Sexually Transmitted Infections Among Transgender Women With and Without HIV in the Eastern and Southern United States.

BACKGROUND: Data on the epidemiology of sexually transmitted infections (STIs) among transgender women (TGW) with and without human immunodeficiency virus (HIV) are limited. METHODS: We analyzed baseline data collected from a cohort of adult TGW across 6 eastern and southern US cities between March 2018 and August 2020 (n = 1018). Participants completed oral HIV screening, provided self-collected rectal and urogenital specimens for chlamydia and gonorrhea testing, and provided sera specimens for syphilis testing. We assessed associations with ≥1 prevalent bacterial STI using modified Poisson regression. RESULTS: Bacterial STI prevalence was high and differed by HIV status: 32% among TGW with HIV and 11% among those without HIV (demographic-adjusted prevalence ratio = 1.91; 95% confidence interval = 1.39-2.62). Among TGW without HIV, bacterial STI prevalence differed by geographic region, race and ethnicity, and gender identity, and was positively associated with reporting >1 sexual partner, hazardous alcohol use, homelessness, having safety concerns regarding transit to health care, and no prior receipt of gender-affirming health services. Among TGW with HIV, older age was inversely associated with bacterial STI. CONCLUSIONS: TGW had a high prevalence of bacterial STIs. The prevalence and correlates of bacterial STI differed by HIV status, highlighting the unique needs and risks of TGW with and without HIV. Tailored interventions may reduce sexual health-related inequities.

Transgender healthcare: metabolic outcomes and cardiovascular risk.

Transgender identity is often associated with gender dysphoria and minority stress. Gender-affirming hormone treatment (GAHT) includes masculinising or feminising treatment and is expected to be lifelong in most cases. Sex and sex hormones have a differential effect on metabolism and CVD in cisgender people, and sex hormone replacement in hypogonadism is associated with higher vascular risk, especially in ageing individuals. Using narrative review methods, we present evidence regarding metabolic and cardiovascular outcomes during GAHT and propose recommendations for follow-up and monitoring of metabolic and cardiovascular risk markers during GAHT. Available data show no increased risk for type 2 diabetes in transgender cohorts, but masculinising GAHT increases lean body mass and feminising GAHT is associated with higher fat mass and insulin resistance. The risk of CVD is increased in transgender cohorts, especially during feminising GAHT. Masculinising GAHT is associated with a more adverse lipid profile, higher haematocrit and increased BP, while feminising GAHT is associated with pro-coagulant changes and lower HDL-cholesterol. Assigned male sex at birth, higher age at initiation of GAHT and use of cyproterone acetate are separate risk factors for adverse CVD markers. Metabolic and CVD outcomes may improve during gender-affirming care due to a reduction in minority stress, improved lifestyle and closer surveillance leading to optimised preventive medication (e.g. statins). GAHT should be individualised according to individual risk factors (i.e. drug, dose and form of administration); furthermore, doctors need to discuss lifestyle and preventive medications in order to modify metabolic and CVD risk during GAHT. Follow-up programmes must address the usual cardiovascular risk markers but should consider that biological age and sex may influence individual risk profiling including mental health, lifestyle and novel cardiovascular risk markers during GAHT.

Effect of testosterone therapy on breast tissue composition and mammographic breast density in trans masculine individuals.

BACKGROUND: The effect of gender-affirming testosterone therapy (TT) on breast cancer risk is unclear. This study investigated the association between TT and breast tissue composition and breast tissue density in trans masculine individuals (TMIs). METHODS: Of the 444 TMIs who underwent chest-contouring surgeries between 2013 and 2019, breast tissue composition was assessed in 425 TMIs by the pathologists (categories of lobular atrophy and stromal composition) and using our automated deep-learning algorithm (% epithelium, % fibrous stroma, and % fat). Forty-two out of 444 TMIs had mammography prior to surgery and their breast tissue density was read by a radiologist. Mammography digital files, available for 25/42 TMIs, were analyzed using the LIBRA software to obtain percent density, absolute dense area, and absolute non-dense area. Linear regression was used to describe the associations between duration of TT use and breast tissue composition or breast tissue density measures, while adjusting for potential confounders. Analyses stratified by body mass index were also conducted. RESULTS: Longer duration of TT use was associated with increasing degrees of lobular atrophy (p < 0.001) but not fibrous content (p = 0.82). Every 6 months of TT was associated with decreasing amounts of epithelium (exp(ß) = 0.97, 95% CI 0.95,0.98, adj p = 0.005) and fibrous stroma (exp(ß) = 0.99, 95% CI 0.98,1.00, adj p = 0.05), but not fat (exp(ß) = 1.01, 95%CI 0.98,1.05, adj p = 0.39). The effect of TT on breast epithelium was attenuated in overweight/obese TMIs (exp(ß) = 0.98, 95% CI 0.95,1.01, adj p = 0.14). When comparing TT users versus non-users, TT users had 28% less epithelium (exp(ß) = 0.72, 95% CI 0.58,0.90, adj p = 0.003). There was no association between TT and radiologist's breast density assessment (p = 0.58) or LIBRA measurements (p > 0.05). CONCLUSIONS: TT decreases breast epithelium, but this effect is attenuated in overweight/obese TMIs. TT has the potential to affect the breast cancer risk of TMIs. Further studies are warranted to elucidate the effect of TT on breast density and breast cancer risk.

Relationship between Androgens and Vascular and Placental Function during Pre-eclampsia.

Hypertensive disorders of pregnancy (HDP) represent a substantial risk to maternal and fetal health. Emerging evidence suggests an association between testosterone and pre-eclampsia (PE), potentially mediated through androgen receptors (AR). Nevertheless, the mechanism driving this association is yet to be elucidated. On the other hand, reports of transgender men's pregnancies offer a limited and insightful opportunity to understand the role of high androgen levels in the development of HDP. In this sense, a literature review was performed from a little over 2 decades (1998-2022) to address the association of testosterone levels with the development of HDP. Furthermore, this review addresses the case of transgender men for the first time. The main in vitro outcomes reveal placenta samples with greater AR mRNA expression. Moreover, ex vivo studies show that testosterone-induced vasorelaxation impairment promotes hypertension. Epidemiological data point to greater testosterone levels in blood samples during PE. Studies with transgender men allow us to infer that exogenous testosterone administration can be considered a risk factor for PE and that the administration of testosterone does not affect fetal development. Overall, all studies analyzed suggested that high testosterone levels are associated with PE.

Getting Precise about Gender and Sex Measurement: A Primer for Epidemiologists.

Accurately measuring gender and sex is crucial in public health and epidemiology. Iteratively reexamining how variables-including gender and sex-are conceptualized and operationalized is necessary to achieve impactful research. Reexamining gender and sex advances epidemiology toward its goals of health promotion and disease elimination. While we cannot reduce the complexities of sex and gender to simply an issue of measurement, striving to capture these concepts and experiences accurately must be an ongoing dialogue and practice-to the benefit of the field and population health. We assert that epidemiology must counteract misconceptions and accurately measure gender and sex in epidemiology. We aim to summarize existing critiques and guiding principles in measuring gender and sex that can be applied in practice.

Cancer in people who identify as lesbian, gay, bisexual, transgender, queer, or gender-nonconforming.

BACKGROUND: Individuals who identify as lesbian, gay, bisexual, transgender, queer, intersex, or gender-nonconforming (LGBTQ+) experience discrimination and minority stress that may lead to elevated cancer risk. METHODS: In the absence of population-based cancer occurrence information for this population, this article comprehensively examines contemporary, age-adjusted cancer risk factor and screening prevalence using data from the National Health Interview Survey, Behavioral Risk Factor Surveillance System, and National Youth Tobacco Survey, and provides a literature review of cancer incidence and barriers to care. RESULTS: Lesbian, gay, and bisexual adults are more likely to smoke cigarettes than heterosexual adults (16% compared to 12% in 2021-2022), with the largest disparity among bisexual women. For example, 34% of bisexual women aged 40-49 years and 24% of those 50 and older smoke compared to 12% and 11%, respectively, of heterosexual women. Smoking is also elevated among youth who identify as lesbian, gay, or bisexual (4%) or transgender (5%) compared to heterosexual or cisgender (1%). Excess body weight is elevated among lesbian and bisexual women (68% vs. 61% among heterosexual women), largely due to higher obesity prevalence among bisexual women (43% vs. 38% among lesbian women and 33% among heterosexual women). Bisexual women also have a higher prevalence of no leisure-time physical activity (35% vs. 28% among heterosexual women), as do transgender individuals (30%-31% vs. 21%-25% among cisgender individuals). Heavier alcohol intake among lesbian, gay, and bisexual individuals is confined to bisexual women, with 14% consuming more than 7 drinks/week versus 6% of heterosexual women. In contrast, prevalence of cancer screening and risk reducing vaccinations in LGBTQ+ individuals is similar to or higher than their heterosexual/cisgender counterparts except for lower cervical and colorectal cancer screening among transgender men. CONCLUSIONS: People within the LGBTQ+ population have a higher prevalence of smoking, obesity, and alcohol consumption compared to heterosexual and cisgender people, suggesting a higher cancer burden. Health systems have an opportunity to help inform these disparities through the routine collection of information on sexual orientation and gender identity to facilitate cancer surveillance and to mitigate them through education to increase awareness of LGBTQ+ health needs.

Considerations in gender-affirming hormone therapy in transgender and gender diverse patients undergoing liver transplantation.

Liver transplantation is lifesaving for patients with end-stage liver disease. Similar to the role of transplantation for patients with end-stage liver disease, gender-affirming hormone therapy (GAHT) can be lifesaving for transgender and gender diverse (TGGD) patients who experience gender dysphoria. However, management of such hormone therapy during the perioperative period is unknown and without clear guidelines. Profound strides can be made in improving care for TGGD patients through gender-affirming care and appropriate management of GAHT in liver transplantation. In this article, we call for the transplant community to acknowledge the integral role of GAHT in the care of TGGD liver transplant candidates and recipients. We review the current literature and describe how the transplant community is ethically obligated to address this health care gap. We suggest tangible steps that clinicians may take to improve health outcomes for this minoritized patient population.

Association between Serum Estradiol and Cardiovascular Health among Transgender Adults Using Gender-Affirming Estrogen Therapy.

INTRODUCTION: Gender-affirming estrogen therapy (GAET) is commonly used for feminization in transgender and non-binary (TNB) individuals, yet the optimal rate of change (ROC) in estradiol levels for cardiovascular health is unclear. We examined the association between serum estradiol levels and cardiovascular-related mortality, adverse events, and risk factors in TNB adults using GAET. METHODS: Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE and Web of Science were systematically searched (inception-April 2023) for original articles reporting serum estradiol levels and cardiovascular-related mortality, adverse events, and risk factors in TNB adults using GAET. Data extraction was completed in duplicate following PRISMA guidelines. Stratified random effects meta-analyses using serum estradiol ROC (serum estradiolbaseline-serum estradiolfollow-up/study duration) was used to assess longitudinal studies (Low:0

Breast and cervical cancer screenings across gender identity: results from the Behavioral Risk Factor Surveillance System before and during the COVID-19 pandemic.

PURPOSE: Although national medical organizations often neglect to include trans and gender diverse (TGD) people in their breast and cervical cancer screening recommendations, the World Profession Association of Transgender Health recommends that TGD people who are at risk for these cancers follow existing guidelines for cisgender women. Despite WPATH's recommendations, TGD people are less likely to get screened in large part due to discrimination. The COVID-19 pandemic has limited access to cancer screenings among cisgender people, but it is unknown how this has impacted TGD people. METHODS: Using national survey data from the Behavioral Risk Factors Surveillance System (BRFSS), we examined differences in cervical and breast cancer screening noncompliance across gender identity at two time points: before and during the COVID-19 pandemic. RESULTS: Screening noncompliance increased during the COVID-19 pandemic among cisgender and TGD people (e.g., transgender men, gender non-conforming people). Compared to cisgender women, transgender men and gender non-conforming respondents had higher odds of breast cancer screening noncompliance before and during COVID-19. Transgender men had lower odds of cervical cancer screening noncompliance than cisgender women before COVID-19, but higher odds during the pandemic. Gender non-conforming respondents also had lower odds of cervical cancer screening noncompliance during COVID-19 compared to cisgender women. CONCLUSIONS: Screening noncompliance for breast and cervical cancer was more common among TGD people than cisgender women; while these disparities existed before the COVID-19 pandemic, they were exacerbated during the pandemic. Future work should move beyond descriptive statistics and elucidate underlying causes to inform interventions.

Impact of Telemedicine on Access to Care for Rural Transgender and Gender-Diverse Youth.

OBJECTIVE: To explore the impact of telemedicine on access to gender-affirming care for rural transgender and gender diverse youth. STUDY DESIGN: A retrospective analysis of data drawn from the electronic medical records of a clinic that provides approximately 10 000 adolescent and young adult visits per year and serves patients seeking gender health care. The no-show rate was examined as a proxy for access to care due to anticipated challenges with recruiting a representative sample of a historically marginalized population. Logistic regression with generalized estimating equations was conducted to model the association between the odds of a no-show visit and covariates of interest. RESULTS: Telemedicine visits, rural home address, gender health visits, longer travel time, and being younger than 18 years old were associated with lower odds of a no-show in univariate models (n = 17 928 visits). In the adjusted model, the OR of no-shows for gender health visits was 0.56 (95% CI 0.42-0.74), adjusting for rurality, telemedicine, age (< or >18 years), and travel time to the clinic. CONCLUSIONS: In this study, telemedicine was associated with reduced no-shows overall, and especially for rural, transgender and gender diverse youth, and patients who hold both identities. Although the no-show rate does not fully capture barriers to access, these findings provide insight into how this vulnerable population may benefit from expanded access to telemedicine for rural individuals whose communities may lack providers with the skills to serve this population.

A Holistic Framework for the Evaluation of Kidney Function in a Gender-Diverse Landscape.

The most commonly used equations to estimate glomerular filtration rate incorporate a binary male-female sex coefficient, which has important implications for the care of transgender, gender-diverse, and nonbinary (TGD) people. Whether "sex assigned at birth" or a binary "gender identity" is most appropriate for the computation of estimated glomerular filtration rate (eGFR) is unknown. Furthermore, the use of gender-affirming hormone therapy (GAHT) for the development of physical changes to align TGD people with their affirmed gender is increasingly common, and may result in changes in serum creatinine and cystatin C, the biomarkers commonly used to estimate glomerular filtration rate. The paucity of current literature evaluating chronic kidney disease (CKD) prevalence and outcomes in TGD individuals on GAHT makes it difficult to assess any effects of GAHT on kidney function. Whether alterations in serum creatinine reflect changes in glomerular filtration rate or simply changes in muscle mass is unknown. Therefore, we propose a holistic framework to evaluate kidney function in TGD people. The framework focuses on kidney disease prevalence, risk factors, sex hormones, eGFR, other kidney function assessment tools, and the mitigation of health inequities in TGD people.

Gender-affirming hormone therapy effect on cortisol levels in trans males and trans females.

PURPOSE: Previous studies have shown differences in baseline and stimulated cortisol levels between men and women. Whether this difference is secondary to sex hormones or to other factors, such as genetic or epigenetic changes, is unknown. We investigated the effect of gender-affirming hormone treatment (GAHT) on the hypothalamo-pituitary-adrenal axis of transgender subjects in an effort to throw light on this question. METHODS: Ten transgender males (TM) and eight transgender females (TF) underwent a low-dose (1 µg) adrenocorticotropic hormone (ACTH) stimulation test before and 6 months after GAHT initiation. Serum total, free and salivary cortisol (SC) levels were measured at baseline and at 20, 30 and 40 min. RESULTS: For the TM, all three levels were significantly lower at several time points after ACTH injection compared to pretreatment levels following 6 months of treatment (p < .05). Likewise, the overall SC response as calculated by the area under the curve was significantly lower (p = .0053). For the TF, the basal total cortisol (TC) level increased after 6 months of treatment (p < .01) while ACTH-stimulated SC levels decreased significantly. The basal ACTH levels were significantly lower following hormonal therapy (p < .001). CONCLUSION: Stimulated salivary cortisol levels decreased significantly after 6 months of GAHT in both male and female transgender subjects, possibly reflecting a decreased state of anxiety associated with treatment initiation. Additionally, basal and stimulated serum TC levels increased after hormonal treatment in the TF, probably secondary to the effect of oestrogen on cortisol-binding globulin.

Identifying priority groups for pre-exposure prophylaxis among sex workers in Flanders, Belgium: insights into routine HIV and sexually transmitted infection data in community-based clinics.

OBJECTIVES: The burden of HIV and other sexually transmitted infections (STIs) remains high in sex workers globally, calling for strengthening targeted prevention strategies, including HIV pre-exposure prophylaxis (PrEP). The study's objective was to assess HIV and STI burden among female, male and transgender sex workers in Flanders, Belgium, to guide targeting of PrEP strategies for sex workers. METHODS: We conducted a retrospective analysis of routine data collected between January 2016 and December 2019 by community-based organisations providing sexual healthcare services for sex workers in Flanders. HIV prevalence stratified by gender was assessed and associations with sociodemographic characteristics were explored using bivariable and multivariable logistic regression. Positivity rates of chlamydia, gonorrhoea and syphilis tests were used as proxy indicators for STI burden. RESULTS: The study included a total of 6028 sex workers, comprising 5617 (93.2%) female, 218 (3.6%) male and 193 (3.2%) transgender sex workers. The HIV prevalence was 0.3% among female, 8.9% among male and 12.3% among transgender sex workers. Engaging in escort sex work and originating from South America or Sub-Saharan Africa were associated with a higher likelihood of having acquired HIV. The positivity rate for gonorrhoea was higher among male sex workers (5.2% vs 2.2%) and syphilis was more frequently detected among male and transgender sex workers (3.0% and 6.1% vs 0.5%), all compared with female sex workers. CONCLUSIONS: HIV combination prevention, including improved access to PrEP, should be strengthened among sex workers in Flanders, with particular attention to male and transgender sex workers.

Anorectal gonorrhoea and chlamydia among transgender women in Brazil: prevalence and assessment of performance and cost of anorectal infection detection and management approaches.

OBJECTIVES: We aimed to determine the prevalence of anorectal Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) among transgender women in Brazil, and to assess the performance and costs of various approaches for the diagnosis and management of anorectal NG/CT. METHODS: TransOdara was a multicentric, cross-sectional STI prevalence study among 1317 transgender women conducted in five capital cities representing all Brazilian regions. Participants aged >18 years were recruited using respondent-driven sampling (RDS), completed an interviewer-led questionnaire, offered an optional physical examination and given choice between self-collected or provider-collected samples for NG/CT testing. Performance and cost indicators of predetermined management algorithms based on the WHO recommendations for anorectal symptoms were calculated. RESULTS: Screening uptake was high (94.3%) and the estimated prevalence of anorectal NG, CT and NG and/or CT was 9.1%, 8.9% and 15.2%, respectively. Most detected anorectal NG/CT infections were asymptomatic (NG: 87.6%, CT: 88.9%), with a limited number of participants reporting any anorectal symptoms (9.1%). Of those who permitted anal examination, few had clinical signs of infection (13.6%). Sensitivity of the tested algorithms ranged from 1.4% to 5.1% (highest for treatment based on the reported anorectal discharge or ulcer and receptive anal intercourse (RAI) in the past 6 months) and specificity from 98.0% to 99.3% (highest for treatment based on the reported anorectal discharge with clinical confirmation or report of RAI). The estimated cost-per-true case of anorectal NG/CT infection treated varied from lowest providing treatment for anorectal discharge syndrome based on the reported RAI ($2.70-4.28), with algorithms including clinical examinations decreasing cost-effectiveness. CONCLUSIONS: High prevalence of mostly asymptomatic anorectal NG and CT was observed among Brazilian transgender women. Multi-site NG/CT screening should be offered to transgender women. Where diagnostic testing capacity is limited, syndromic management for those presenting with anorectal symptoms is recommended.

Hepatitis C virus infection is uncommon at baseline and during follow-up among individuals using PrEP in the Dutch national PrEP programme between 2019 and 2022.

OBJECTIVES: Studies showed that men who have sex with men (MSM), including those using pre-exposure prophylaxis (PrEP), are at increased risk of hepatitis C virus (HCV) infection. We evaluated HCV prevalence and incidence, along with their associated determinants, in a cohort of PrEP-using individuals in the Netherlands. METHODS: In 2019, the Netherlands launched a 5-year national programme that offers subsidised PrEP to eligible individuals. We used prospectively collected data from individuals registered in this programme between 2019 and 2022. Individuals underwent annual testing for HCV antibodies and additional HCV-RNA testing when antibodies were present. We calculated the prevalence of past/current HCV infection at first visit and overall incidence rate (IR) during follow-up. Univariable logistic and Poisson regression models were used to identify determinants associated with past/current prevalent or incident HCV infection, respectively. Behavioural factors referred to those occurring in the previous 6 months. RESULTS: A total of 10 563 (n=10 319, 97.7% MSM) were included. At first visit, 66 of 10 563 (0.6%) had a past/current HCV infection, which was associated with older age [odds ratio (OR) per 10 years=1.57, 95% confidence interval (CI)=1.31 to 1.88], the use of PrEP before first visit (OR=3.03, 95% CI=1.79 to 5.13), receptive condomless anal sex (CAS) (OR=2.73, 95% CI=1.25 to 5.98), chemsex (OR=2.44, 95% CI=1.49 to 3.99) and injecting drug use (IDU) (OR=6.61, 95% CI=2.35 to 18.61). Among 9851 individuals contributing to 17 150 person-years (PYs) of follow-up, 64 incident HCV infections (IR=0.37 per 100 PYs, 95% CI=0.29 to 0.48) were identified. Factors associated with incident HCV infection were receptive CAS [incidence rate ratio (IRR)=2.59, 95% CI=1.12 to 6.02], chemsex (IRR=1.78, 95% CI=1.06 to 2.98), sexually transmitted infection diagnosis (IRR=2.30, 95% CI=1.23 to 4.31) and IDU (IRR=6.15, 95% CI=2.20 to 17.18). CONCLUSIONS: Past/current prevalence and incidence of HCV were low among individuals in the Dutch PrEP programme. Infections were associated with behaviour known to be associated with HCV. Instead of annual HCV testing, as stated in most PrEP care guidelines, testing frequency for HCV could be based on behaviours associated with HCV acquisition.