A transgender person is someone whose sex assigned at birth does not match their gender identity (i.e. their sense of being a man, woman or an alternative gender). Hormone therapy, containing oestrogen or testosterone, aims to align a persons characteristics with their gender identity. While high quality information is limited, it is estimated that approximately one in 200 people in the UK are transgender and 70-90% use hormone therapy.
While the numbers of transgender people are increasing, their health needs are poorly understood. Our study will aim to: 1) develop methods to study transgender people using primary care data; 2) estimate the number of transgender people in the UK; 2) describe how often transgender people experience risk factors (e.g. smoking, obesity, high blood pressure, drinking unhealthy amounts of alcohol) for common diseases; 3) describe how often transgender people experience mental health conditions (anxiety, depression, schizophrenia, bipolar disorder, autistic spectrum disorder); 4) describe how often transgender people experience common physical health conditions (heart attacks, stroke, cancer, blood clots and gallbladder disease); 5) describe the death rate amongst transgender people; and 6) establish whether any associations between transgender identity and health conditions differ by deprivation. For all of these objectives, we will compare health outcomes of transgender people to cisgender people (i.e. people whose sex at birth matches their gender identity).
Our study has been developed following discussions with members of the trans community and will help ensure health services appropriately respond to the needs of this potentially vulnerable community.
Transgender people experience gender dysphoria due to incongruence between their gender identity and the sex they were assigned at birth. Gender-affirming hormone therapy (testosterone, oestrogen, GnRH analogues and anti-androgens) aim to align the characteristics of transgender people with their gender identity, however, our appreciation of the effects of such treatments on health outcomes is limited.
Research relating to the prevalence of transgender individuals, the risk factors for non-communicable diseases, morbidity (for mental and physical health conditions) and mortality outcomes in transgender people compared to cisgender people is limited by the absence of large cohort studies; lack of appropriate control populations and inadequate data acquisition from gender identity services.
We will use CPRD Gold and Aurum data to define a cohort of transgender individuals between the ages of 16-74 between the study dates of 1 January 1997 and 31st March 2020. We will perform analyses on all transgender individuals and age-sex-GP practice matched cisgender individuals (20 cisgender male and 20 cisgender female controls per transgender individual). Our aims will be to develop, validate and describe a transgender phenotype in the UK, and to profile common risk factors for non-communicable diseases, the incidence of common mental and physical health conditions (cardiovascular disease, stroke, cancer and gallbladder disease), and assess mortality outcomes compared to cisgender people.
We will calculate prevalence risk ratios for each of the risk factors of interest utilising logistic regression and estimation of average marginal effects. One year and lifetime period prevalence will be calculated for common (e.g. depression, anxiety) and rarer (e.g. schizophrenia, bipolar disorder, autistic spectrum disorder) mental health conditions respectively. Cox proportional hazard modelling for the incident common non-communicable diseases, mental health conditions, and disease-specific mortality will be undertaken, adjusting for age, ethnicity and deprivation. Age-standardised mortality rates will also be calculated.
We have chosen outcomes to that are of high interest to researchers, health policy makers as well as transgender people who we have consulted about our study plans.
Prevalence outcomes
Common risk factors for non-communicable diseases:
Alcohol consumption
Smoking
Body mass index
Hypertension
Diabetes
Chronic Kidney Disease
Rheumatoid Arthritis
Dyslipidaemia
Mental health outcomes:
Depression
Anxiety
Common mood disorder (depression or anxiety)
Autistic spectrum disorder
Schizophrenia and bipolar disorder
Incident outcomes
Cardiovascular disease
Stroke
Thromboembolic events
All cancers (excluding non-malignant skin cancers)
Gallbladder disease
Mortality outcomes
All-cause mortality
Cause-specific mortality
Srinivasa Vittal Katikireddi - Chief Investigator - University of Glasgow
Srinivasa Vittal Katikireddi - Corresponding Applicant - University of Glasgow
Bhautesh Jani - Collaborator - University of Glasgow
Christian Delles - Collaborator - University of Glasgow
Claire Niedzwiedz - Collaborator - University of Glasgow
Daniel Mackay - Collaborator - University of Glasgow
David Blane - Collaborator - University of Glasgow
Desmond Campbell - Collaborator - University of Glasgow
Frederick Ho - Collaborator - University of Glasgow
Jill Pell - Collaborator - University of Glasgow
Kirsten Hainey - Collaborator - University of Glasgow
Kirsten Mitchell - Collaborator - University of Glasgow
Naveed Sattar - Collaborator - University of Glasgow
Paul Connelly - Collaborator - University of Glasgow
Paul Welsh - Collaborator - University of Glasgow
Rachel Thomson - Collaborator - University of Glasgow
Robert Aldridge - Collaborator - University College London ( UCL )
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation