Diana M. Tordoff, PhD, MPH is a postdoctoral scholar with The PRIDE Study ( at the Stanford School of Medicine. She is an epidemiologist whose research focuses on LGBTQ+ health equity. Prior to joining The PRIDE Study, Diana was awarded an NIH Kirschstein National Research Service Fellowship for her doctoral dissertation, which examined the heterogeneity in HIV/STI prevalence, testing, and PrEP use among transgender and non-binary people and their partners in the US. Her interests include barriers and facilitators of healthcare access for LGBTQ+ communities, sexual and reproductive health, HIV/STI prevention, sexual orientation & gender identity (SOGI) measurement, phylogenetics and molecular epidemiology, and community-engaged research methods.

Honors & Awards

  • Ruth L. Kirschstein National Research Service Award Individual Predoctoral Fellowship (F31AI152542), National Institutes of Allergy and Infectious Diseases (2020-2022)

Professional Education

  • Doctor of Philosophy, University of Washington (2022)
  • Master of Public Health, University of Washington (2018)
  • Bachelor of Arts, Vassar College (2011)

All Publications

  • Mental Health Outcomes in Transgender and Nonbinary Youths Receiving Gender-Affirming Care. JAMA network open Tordoff, D. M., Wanta, J. W., Collin, A., Stepney, C., Inwards-Breland, D. J., Ahrens, K. 2022; 5 (2): e220978


    Transgender and nonbinary (TNB) youths are disproportionately burdened by poor mental health outcomes owing to decreased social support and increased stigma and discrimination. Although gender-affirming care is associated with decreased long-term adverse mental health outcomes among these youths, less is known about its association with mental health immediately after initiation of care.To investigate changes in mental health over the first year of receiving gender-affirming care and whether initiation of puberty blockers (PBs) and gender-affirming hormones (GAHs) was associated with changes in depression, anxiety, and suicidality.This prospective observational cohort study was conducted at an urban multidisciplinary gender clinic among TNB adolescents and young adults seeking gender-affirming care from August 2017 to June 2018. Data were analyzed from August 2020 through November 2021.Time since enrollment and receipt of PBs or GAHs.Mental health outcomes of interest were assessed via the Patient Health Questionnaire 9-item (PHQ-9) and Generalized Anxiety Disorder 7-item (GAD-7) scales, which were dichotomized into measures of moderate or severe depression and anxiety (ie, scores ≥10), respectively. Any self-report of self-harm or suicidal thoughts over the previous 2 weeks was assessed using PHQ-9 question 9. Generalized estimating equations were used to assess change from baseline in each outcome at 3, 6, and 12 months of follow-up. Bivariate and multivariable logistic models were estimated to examine temporal trends and investigate associations between receipt of PBs or GAHs and each outcome.Among 104 youths aged 13 to 20 years (mean [SD] age, 15.8 [1.6] years) who participated in the study, there were 63 transmasculine individuals (60.6%), 27 transfeminine individuals (26.0%), 10 nonbinary or gender fluid individuals (9.6%), and 4 youths who responded "I don't know" or did not respond to the gender identity question (3.8%). At baseline, 59 individuals (56.7%) had moderate to severe depression, 52 individuals (50.0%) had moderate to severe anxiety, and 45 individuals (43.3%) reported self-harm or suicidal thoughts. By the end of the study, 69 youths (66.3%) had received PBs, GAHs, or both interventions, while 35 youths had not received either intervention (33.7%). After adjustment for temporal trends and potential confounders, we observed 60% lower odds of depression (adjusted odds ratio [aOR], 0.40; 95% CI, 0.17-0.95) and 73% lower odds of suicidality (aOR, 0.27; 95% CI, 0.11-0.65) among youths who had initiated PBs or GAHs compared with youths who had not. There was no association between PBs or GAHs and anxiety (aOR, 1.01; 95% CI, 0.41, 2.51).This study found that gender-affirming medical interventions were associated with lower odds of depression and suicidality over 12 months. These data add to existing evidence suggesting that gender-affirming care may be associated with improved well-being among TNB youths over a short period, which is important given mental health disparities experienced by this population, particularly the high levels of self-harm and suicide.

    View details for DOI 10.1001/jamanetworkopen.2022.0978

    View details for PubMedID 35212746

    View details for PubMedCentralID PMC8881768

  • Trans Youth Talk Back: A Foucauldian Discourse Analysis of Transgender Minors' Accounts of Healthcare Access QUALITATIVE HEALTH RESEARCH Shook, A. G., Tordoff, D. M., Clark, A., Hardwick, R., St. Pierre Nelson, W., Kantrowitz-Gordon, I. 2022; 32 (11): 1672-1689


    Contemporary transgender youth in the U.S. today face increasing stigmatization as extraordinary legislative attacks intensify discrimination and exclusion of these young people in healthcare, recreation, and school life. These attacks reflect broader political, religious, and cultural ideologies embedded in systems of power that regulate the provision of healthcare for American transgender youth. We apply Foucauldian discourse analysis and a theory-driven conceptual framework for structural analysis of transgender health inequities-Intersectionality Research for Transgender Health Justice-to identify discourses youth encounter within healthcare practice. We analyzed data from interviews conducted in Western Washington State with youth ages 13-17 (n =11) and asked how transgender subjectivity was constructed in their accounts and in what ways youth made use of the discursive resources available to them when navigating systems of care. Three sets of discourses-discourses of normativity, discourses of temporality, and discourse of access-characterized participants' narratives. We discuss how participants negotiated discursively situated systems of power in order to ensure their safety and access to care.

    View details for DOI 10.1177/10497323221114801

    View details for Web of Science ID 000823629400001

    View details for PubMedID 35818038

  • Trans-inclusive Sexual Health Questionnaire to Improve HIV/STI Care for Transgender Patients: Anatomic-site Specific STI Prevalence & Screening Rates. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America Tordoff, D. M., Dombrowski, J. C., Ramchandani, M. S., Barbee, L. A. 2022


    In 2018, the municipal Sexual Health Clinic in Seattle implemented trans-inclusive questions about sexual behavior, anatomy, gender-affirming surgeries, and STI symptoms in the clinic's computer-assisted self-interview (CASI) to improve care for transgender and non-binary (TNB) patients.We calculated test positivity and the proportion of TNB patient visits that received testing for HIV, syphilis, pharyngeal, rectal and urogenital gonorrhea (GC) and chlamydia (CT) before (5/2016-12/2018) and after (12/2018-2/2020) implementation of new CASI questions. We then calculated the proportion of asymptomatic patients who received anatomic-site specific screening based on reported exposures.There were 434 TNB patients with 489 and 337 clinic visits during the two periods, respectively. Non-binary patients assigned male at birth (AMAB) had the highest prevalence of GC (10% pharyngeal, 14% rectal, 12% urogenital). Transgender women, transgender men, and non-binary people AMAB had a high prevalence of rectal CT (10%, 9%, and 13%, respectively) and syphilis (9%, 5%, and 8%). Asymptomatic transgender women, transgender men and non-binary patients AMAB who reported exposures were more likely to receive extragenital GC/CT screening compared to non-binary patients assigned female at birth. After implementing trans-inclusive medical history questions, there was a 33% increase in the number of annual TNB patient visits, but no statistically significant increase HIV/STI testing among TNB patients.TNB people at our clinic had a high prevalence of extragenital STIs and syphilis. Implementation of trans-inclusive medical history questions at a clinic that serves cisgender and transgender patients was feasible and important for improving the quality of affirming and inclusive sexual healthcare.

    View details for DOI 10.1093/cid/ciac370

    View details for PubMedID 35594554

  • Geographic Variation in HIV Testing Among Transgender and Nonbinary Adults in the United States. Journal of acquired immune deficiency syndromes (1999) Tordoff, D. M., Zangeneh, S., Khosropour, C. M., Glick, S. N., McClelland, R. S., Dimitrov, D., Reisner, S., Duerr, A. 2022; 89 (5): 489-497


    Transgender and nonbinary (TNB) populations are disproportionately affected by HIV and few local health departments or HIV surveillance systems collect/report data on TNB identities. Our objective was to estimate the prevalence of HIV testing among TNB adults by US county and state, with a focus on the Ending the HIV Epidemic (EHE) geographies.We applied a Bayesian hierarchical spatial small area estimation model to data from the 2015 US Transgender Survey, a large national cross-sectional Internet-based survey. We estimated the county- and state-level proportion of TNB adults who ever tested or tested for HIV in the last year by gender identity, race/ethnicity, and age.Our analysis included 26,100 TNB participants with valid zip codes who resided in 1688 counties (54% of all 3141 counties that cover 92% of the US population). The median county-level proportion of TNB adults who ever tested for HIV was 44% (range 10%-80%) and who tested in the last year was 17% (range 4%-44%). Within most counties, testing was highest among transgender women, black respondents, and people aged ≥25 years. HIV testing was lowest among nonbinary people and young adults aged <25 years. The proportion of TNB adults who tested within the last year was very low in most EHE counties and in all 7 rural states.HIV testing among TNB adults is likely below national recommendations in the majority of EHE geographies. Geographic variation in HIV testing patterns among TNB adults indicates that testing strategies need to be tailored to local settings.

    View details for DOI 10.1097/QAI.0000000000002909

    View details for PubMedID 35001041

    View details for PubMedCentralID PMC9058176

  • Erasure and Health Equity Implications of Using Binary Male/Female Categories in Sexual Health Research and Human Immunodeficiency Virus/Sexually Transmitted Infection Surveillance: Recommendations for Transgender-Inclusive Data Collection and Reporting. Sexually transmitted diseases Tordoff, D. M., Minalga, B., Gross, B. B., Martin, A., Caracciolo, B., Barbee, L. A., Balkus, J. E., Khosropour, C. M. 2022; 49 (2): e45-e49

    View details for DOI 10.1097/OLQ.0000000000001533

    View details for PubMedID 34407018

    View details for PubMedCentralID PMC8755589

  • Sex Education for Transgender and Non-Binary Youth: Previous Experiences and Recommended Content. The journal of sexual medicine Haley, S. G., Tordoff, D. M., Kantor, A. Z., Crouch, J. M., Ahrens, K. R. 2019; 16 (11): 1834-1848


    Transgender and non-binary (TNB) youth face disparities in sexual health risks compared with cisgender peers. Comprehensive sex education programs have the potential to result in delayed sexual debut, increased condom and contraceptive use, and reduced sexual risk-taking; however, little research has explored the specific sex education needs of TNB youth.To use insights from TNB youth, parents of TNB youth, and healthcare affiliates to understand deficits in sex education experienced by TNB youth, and to elicit recommended content for a comprehensive and trans-inclusive sex education curriculum.We conducted 21 in-depth interviews with non-minor TNB youth (n = 11) and with parents (n = 5) and healthcare affiliates (n = 5) of TNB youth recruited from Seattle Children's Gender Clinic and local TNB community listerv readerships. Data was analyzed using theoretical thematic analysis.Participants described prior sex education experiences and content needs of TNB youth.Participants described 5 key sources where TNB youth received sexual health information: school curricula, medical practitioners, peers, romantic partners, and online media. Inapplicability of school curricula and variable interactions with medical practitioners led youth to favor the latter sources. 8 content areas were recommended as important in sex education for TNB youth: puberty-related gender dysphoria, non-medical gender-affirming interventions, medical gender-affirming interventions, consent and relationships, sex and desire, sexually transmitted infection prevention, fertility and contraception, and healthcare access.Dependence on potentially inaccurate sex education sources leaves TNB youth vulnerable to negative outcomes, including sexually transmitted infections, pregnancy, unsanitary/unsafe sex toy use, and shame about their body or sexual desires.Strengths included capturing perspectives of an underserved population using open-ended interview questions, which allowed topics of greatest importance to participants to arise organically. Limitations included a sample size of 21 participants, and racial and geographic homogeneity of youth and parent participants. Only 1 author identifies as TNB. One-on-one interview methods may have omitted participants who would otherwise have been willing to share their perspective in a more impersonal format.This study demonstrates that TNB youth have unique sex education needs that are not well covered in most sexual health curricula. Recommended content for this population includes standard sex education topics that require trans-inclusive framing (eg, contraception), topics specific to TNB youth (eg, gender-affirming medical interventions), and topics absent from standard curricula that warrant universal teaching (eg, information on consent as it relates to sex acts aside from penile-vaginal sex). Haley SG, Tordoff DM, Kantor AZ, et al. Sex Education for Transgender and Non-Binary Youth: Previous Experiences and Recommended Content. J Sex Med 2019;16:1834-1848.

    View details for DOI 10.1016/j.jsxm.2019.08.009

    View details for PubMedID 31585806

  • Misclassification of Sex Assigned at Birth in the Behavioral Risk Factor Surveillance System and Transgender Reproductive Health: A Quantitative Bias Analysis. Epidemiology (Cambridge, Mass.) Tordoff, D., Andrasik, M., Hajat, A. 2019; 30 (5): 669-678


    National surveys based on probability sampling methods, such as the Behavioral Risk Factor and Surveillance System (BRFSS), are crucial tools for unbiased estimates of health disparities. In 2014, the BRFSS began offering a module to capture transgender and gender nonconforming identity. Although the BRFSS provides much needed data on the this population, these respondents are vulnerable to misclassification of sex assigned at birth.We applied quantitative bias analysis to explore the magnitude and direction of the systematic bias present as a result of this misclassification. We use multivariate Poisson regression with robust standard errors to estimate the association between gender and four sex-specific outcomes: prostate-specific antigen testing, Pap testing, hysterectomy, and pregnancy. We applied single and multiple imputation methods, and probabilistic adjustments to explore bias present in these estimates.Combined BRFSS data from 2014, 2015, and 2016 included 1078 transgender women, 701 transgender men, and 450 gender nonconforming individuals. Sex assigned at birth was misclassified among 29.6% of transgender women and 30.2% of transgender men. Transgender and gender nonconforming individuals excluded due to sex-based skip patterns are demographically distinct from those who were asked reproductive health questions, suggesting that there is noteworthy selection bias present in the data. Estimates for gender nonconforming respondents are vulnerable to small degrees of bias, while estimates for cancer screenings among transgender women and men are more robust to moderate degrees of bias.Our results demonstrate that the BRFSS methodology introduces substantial uncertainty into reproductive health measures, which could bias population-based estimates. These findings emphasize the importance of implementing validated sex and gender questions in health surveillance surveys. See video abstract at,

    View details for DOI 10.1097/EDE.0000000000001046

    View details for PubMedID 31162292

  • Increased Ascertainment of Transgender and Non-binary Patients Using a 2-Step Versus 1-Step Gender Identity Intake Question in an STD Clinic Setting. Sexually transmitted diseases Tordoff, D. M., Morgan, J., Dombrowski, J. C., Golden, M. R., Barbee, L. A. 2019; 46 (4): 254-259


    Transgender inclusive and gender affirmative healthcare includes asking patients about gender identity and sex assigned at birth through what is known as the "2-step" methodology. In May 2016, the sexually transmitted disease (STD) clinic in Seattle, WA switched from using a 1-step to a 2-step gender identity question. We aimed to determine if the updated questions increased ascertainment of transgender and gender nonconforming (TGNC) patients and used the improved gender identity data to describe the human immunodeficiency virus/STD risk profile of TGNC patients.We conducted a pre-post analysis comparing the proportion of patients that identified as TGNC during the year before and after implementation of the 2-step questions. Gender identity and medical history questions were ascertained using a computer-assisted self-interview. The 2-step question included 2 new gender response options: non-binary/genderqueer and write-in.Institution of the 2-step question resulted in a 4.8-fold increase in patients who were identified as TGNC: 36 (0.5%) of 6635 to 172 (2.4%) of 7025 patients (P < 0.001). After implementation, 89 patients identified as non-binary/genderqueer (51.7% of TGNC patients). The proportion of patients identified as transgender men and women increased from 0.2% to 0.5% (P = 0.002) and 0.4% to 0.6% (P = 0.096), respectively. Non-binary patients' human immunodeficiency virus/sexually transmitted infection risk profile was distinct from that of transgender and cisgender men who have sex with men, suggesting that distinguishing subpopulations within the TGNC population is important for risk stratification.Using a 2-step gender identity question and including non-binary/genderqueer options increased our clinic's ascertainment of TGNC patients and more accurately captured gender identity among STD clinic patients.

    View details for DOI 10.1097/OLQ.0000000000000952

    View details for PubMedID 30516726