Mental Health, Gender Dysphoria, and Quality of Life in Trans Individuals Following Top Surgery: Protocol for a Prospective Cohort Study.

Background: Top surgery refers to various gender-affirming surgical procedures involving breast or chest tissue. Existing research suggests top surgery improves physical, psychological, and social well-being in transgender and gender-diverse individuals (herein "trans") who desire it. However, most studies have been retrospective, have not used validated outcome measures, and have excluded nonbinary individuals, limiting the robustness of the existing research. Objective: This study aims to examine changes in mental health, gender dysphoria, risky behaviors, and quality of life of trans people (including nonbinary individuals) following top surgery. Methods: Trans individuals aged 16 years and older undergoing top surgery will be recruited from a single surgeon's office in Perth, Western Australia, as part of a longitudinal, prospective cohort study. Questionnaires will be administered to participants at 3 time points: within 8 weeks prior to surgery, 6-8 weeks post surgery, and 1 year post surgery. These questionnaires will collect data on patient demographics, planning and expectations for surgery, support received during surgery access, satisfaction with care received from their surgeon, use of gender-affirming hormones, mental health (ie, anxiety, depression, self-harm and suicide, and mental health diagnoses), gender euphoria and dysphoria, exercise and diet, disordered eating, quality of life, substance use, social acceptance and discrimination, and reflections on the experience and outcomes of their surgery. Patient-reported outcomes will be measured using validated instruments and bespoke items developed through community consultation. Validated instruments include the GENDER-Q (health professional subscale); the Generalized Anxiety Disorder 7-item; the Patient Health Questionnaire-9; the Gender Euphoria Scale; an adapted version of the Olson-Kennedy Chest Dysphoria Scale; the International Physical Activity Questionnaire - Short Form; the Eating Disorder Examination Questionnaire - Short; the Assessment of Quality of Life 8 Dimensions; and the Alcohol, Smoking, and Substance Involvement Screening Test - Short Form. Surgical satisfaction will be assessed using both patient- and surgeon-reported measures, enabling between-group comparisons. Quantitative data will be analyzed using linear regression models and repeated-measures ANOVA to compare outcomes across the 3 time points; qualitative data will undergo a general inductive approach to analysis to produce categories that contextualize and supplement the quantitative findings, as well as identify any novel or unexpected experiences. Results: This study received funding in February 2024. Data collection commenced in May 2025 and is expected to be completed by December 2027. As of February 2026, 26 people have consented to participate. Conclusions: This study will extend research on the mental health, gender dysphoria, and quality-of-life outcomes of top surgery for trans individuals in Australia. By addressing limitations of existing research, this study aims to improve our understanding of trans people's experience accessing and receiving top surgery. The findings may guide improvements in perioperative and postoperative care and support for patients and inform policy related to gender-affirming surgeries in Australia.