Patients & Providers: STRONG Evidence To Support Transgender Health

The STRONG study is the first of its kind to research long-term health outcomes of transgender patients in the US. The results will bolster the evidence used in developing standards of care and public policy.

STRONG Evidence To Support Transgender Health

by Michael Goodman


How does one decide on the proper course of treatment?  In modern medicine, this decision should be based on credible scientific evidence.  Very little such evidence is available in transgender health care.  

To date, most studies evaluating health and well-being of transgender people in the United States focused on substance use and abuse, sexual health (mostly HIV infection), and to a lesser extent, mental health problems. By contrast, limited U.S. research is available on basic general health issues such as mortality, frequency and risk factors of treatment complications, and with the exception of very few studies, very sparse information exists on the risks of cancer, osteoporosis, diabetes, and other age-related chronic conditions thought to be affected by hormonal therapy.

Where is the pile of evidence for trans health?

The few available studies are difficult to interpret because they are often based on convenience samples and most are cross-sectional (that is, conducted at one point in time, rather than over a longer period, and therefore incapable of distinguishing between suspected causes and effects).  As noted in the landmark 2011 Institute of Medicine report “The Health of Lesbian, Gay, Bisexual, and Transgender People: Building a Foundation for Better Understanding”, these are important limitations of the current scientific knowledge and “all aspects of the evidence base for transgender-specific health care need to be expanded.” (1)

Why Do We Need “Evidence”?

In the absence of hard empirical evidence, the standards of care published by the World Professional Association for Transgender Health (WPATH) are often based on expert professional consensus or use data from studies of non-transgender men and women (2).  For example, current recommendations regarding risk of venous thrombosis (abnormal blood clots) in transfeminine patients receiving estrogen are based on the observed effects of hormone replacement therapy in women treated for menopause related symptoms.  Similarly, expected health risks in transmasculine individuals are inferred from health problems associated with polycystic ovary syndrome.  In issuing their recommendations, the WPATH members repeatedly ask for more and better data pertaining specifically to transgender patients; however, such data cannot be generated without rigorous research.

The lack of high quality data also offers an excuse to deny transgender health care.  For example, in 2016 the Centers for Medicare and Medicaid Services (CMS) announced the decision to not issue a National Coverage Determination (NCD) on gender reassignment surgery for Medicare beneficiaries with gender dysphoria because the clinical evidence was deemed inconclusive.  In its decision memo the CMS indicated that it “encourages robust clinical studies that will fill the evidence gaps and help inform which patients are most likely to achieve improved health outcomes with gender reassignment surgery, which types of surgery are most appropriate, and what types of physician criteria and care setting(s) are needed to ensure that patients achieve improved health outcomes.” (3)

Where Do We Get Data?

Rigorous research data come from well-designed large-scale studies, and well-designed large-scale studies require time, commitment and resources.  It all comes down to funding.  

A recent analysis of funding awarded by the National Institutes of Health found only 43 studies investigating transgender health topics (4).  After removing studies focusing on HIV/AIDS and other sexual health matters, that number came down to just 14.  There was only one transgender health study assessing risk of hormone-related cancers, and none of the funded studies focused on metabolic and cardiovascular diseases that may be linked to hormones.

A desert of data

According to some estimates, there are as many 1.4 million transgender people in the United States (5).  This number is about the same as the population of Hawaii, and is greater than the populations of 10 US States (Maine and Delaware, for example).  Despite urgent need for more and better data, today we still know relatively little which hormonal treatments are associated with greater risks and greater benefits, what is the frequency of post-surgical complications following gender affirmation, and what types of conditions may require screening or other forms of monitoring in transgender people of older age.  Important unanswered questions are not limited to adults.  Many transgender children and adolescents, their parents, and their physicians need to know when transgender people begin questioning their gender identity, what is the natural history of such gender questioning, and at what age one can begin gender affirmation.  Without trustworthy science, answers to these questions will remain unclear, and a decision on what is “medically necessary” will be a matter of opinion.   

STRONG Research

The existing knowledge gaps motivated the design of the Study of Transition, Outcomes and Gender (STRONG), which received most of its funding support from the Patient Centered Outcomes Research Institute. The study includes two components. First, the electronic medical records (EMR) of transgender individuals enrolled in the in three Kaiser Permanente health plans located in Georgia and California will provide critical data on the health status of transgender people overall, by gender identity and following various stages of transgender treatment. The second component is a survey of selected study participants. The survey will assess the roles of various gender affirmation steps in improving quality of life among transgender people.

STRONG rocks!

STRONG is well-positioned to fill existing knowledge gaps through comparisons of transgender participants with non-transgender people enrolled in the same health plans, as well as analyses of health status before and after hormonal and surgical gender affirmation. 

The data collection for the study is now complete and the analyses of the data are on-going. These analyses will examine risks of cardiovascular disease, incidence of cancer, mental health status, changes in laboratory tests results, as well as measures of quality of life and body image.  More importantly, a number of additional research questions will be addressed with extended follow up of the existing study participants.

Once the results are published, the study will allow incorporating much-needed evidence into the next version of WPATH and other treatment guidelines.


  1. Institute of Medicine. The Health of Lesbian, Gay, Bisexual, and Transgender People: Building a Foundation for Better Understanding. The National Academies Press; Washington, DC, 2011.
  2. Coleman E, Bockting WO, Botzer M, et al. Standards of care for the health of transsexual, transgender, and gender-nonconforming people, version 7. Int J Transgenderism 2012;13:165-232
  3.  Coulter RW, Kenst KS, Bowen DJ, et al. Research funded by the National Institutes of Health on the health of lesbian, gay, bisexual, and transgender populations. Am J Public Health 2014;104:e105-112
  4.  Centers for Medicare & Medicaid Services. Decision Memo for Gender Dysphoria and Gender Reassignment Surgery (CAG-00446N) Rockville, MD Department of Health and Human Services 2016.
  5.  Flores A, Herman J, Gates G, Brown. How Many Adults Identify as Transgender in the United States. The Williams Institute, UCLA School of Law 2016 Los Angeles, CA

About Dr. Goodman

Michael Goodman, MD MPH is a Professor of Epidemiology, at the Emory University Rollins School of Public Health.  He is a licensed physician with board-certification in Pediatrics and Preventive Medicine.  The specific focus of Dr. Goodman’s current research is on health status of transgender people.  In addition to his research activities, Dr. Goodman teaches epidemiology both at Emory and at the Centers for Disease Control and Prevention (CDC).


Community Voices

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s