Epidemiological considerations in transgender health: A systematic review with focus on higher quality data

Qi Zhang; Michael Goodman; Noah Adams; Trevor Corneil; Leila Hashemi; Baudewijntje Kreukels; Joz Motmans; Rachel Snyder; Eli Coleman

doi:10.1080/26895269.2020.1753136

Epidemiological considerations in transgender health: A systematic review with focus on higher quality data

Int J Transgend Health. 2020 Apr 15;21(2):125-137. doi: 10.1080/26895269.2020.1753136. eCollection 2020.

Authors

Qi Zhang¹, Michael Goodman¹, Noah Adams², Trevor Corneil³, Leila Hashemi⁴, Baudewijntje Kreukels⁵, Joz Motmans⁶, Rachel Snyder¹, Eli Coleman⁷

Affiliations

¹ Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, Georgia, USA.
² Ontario Institute for Studies in Education, University of Toronto, Toronto, Canada.
³ Department of Epidemiology, Biostatistics and Public Health Practice University of British Columbia School of Population and Public Health, Vancouver, Canada.
⁴ VA Greater Los Angeles Health Care System, Los Angeles, California, USA.
⁵ Department of Medical Psychology Amsterdam University Medical Centers, location VU, Amsterdam, Netherlands.
⁶ Department of Languages and Cultures, Ghent University, Ghent, Belgium.
⁷ Department of Family Medicine and Community Health University of Minnesota Medical School, Minneapolis, MN, USA.

Abstract

Background: High quality data pertaining to the size of the transgender and gender diverse (TGD) population are scant, however, several recently published studies may provide more reliable contemporary estimates. Aims: To summarize the estimated number and proportion of TGD individuals overall and across age groups, based on most accurate data. Methods: This systematic review focused on recent studies (published from 2009 through 2019) that utilized sound methodology in assessing the proportion of TGD people in the general population. Publications were included if they used clear definitions of TGD status, and calculated proportions based on a well-defined sampling frame. Nineteen eligible publications represented two broad categories of studies: those that used data from large health care systems; and those that identified TGD individuals from population surveys. Results: Among health system-based studies, TGD persons were identified using relevant diagnostic codes or clinical notes. The proportions of individuals with a TGD-relevant diagnosis or other recorded evidence ranged between 17 and 33 per 100,000 enrollees. In population surveys TGD status was ascertained based on self-report with either narrow or broad definitions. The survey-based estimates were orders of magnitude higher and consistent across studies using similar definitions. When the surveys specifically inquired about 'transgender' identity, the estimates ranged from 0.3% to 0.5% among adults, and from 1.2% to 2.7% among children and adolescents. When the definition was expanded to include broader manifestations of 'gender diversity', the corresponding proportions increased to 0.5-4.5% among adults and 2.5-8.4% among children and adolescents. Upward temporal trends in the proportion of TGD people were consistently observed. Conclusions: Current data indicate that people who self-identify as TGD represent a sizable and increasing proportion of the general population. This proportion may differ, depending on inclusion criteria, age, and geographic location, but well-conducted studies of similar type and design tend to produce comparable results.

Keywords: Epidemiology; PRISMA; gender diverse; gender nonconforming; population; systematic review; transgender.

Publication types

Review