Comparison of Depression, Suicidal Ideation, and Stigma between HIV Pre-exposure Prophylaxis Users and Non-users in Men Who Have Sex with Men and Transgender Women in Chiang Mai, Thailand

Background Men who have sex with men (MSM) and transgender women (TGW) face high rates of depression, suicidal thoughts, and stigma due to overlapping social, structural, and psychological challenges. While pre-exposure prophylaxis (PrEP) effectively prevents HIV, its impact on mental health in Southeast Asia remains understudied. This study compared depression, suicidal ideation, and stigma levels between MSM and TGW who use PrEP and those who do not. Methods A cross-sectional study was conducted in Chiang Mai, Thailand. Participants were recruited from two key population-focused clinics. Inclusion criteria were 1) age ≥ 20 years, 2) self-identification as MSM or TGW, 3) having taken PrEP for ≥ 6 months (PrEP user group) or never taking PrEP (non-user group), and 4) willingness to join the study. Participants completed structured questionnaires, including the Patient Health Questionnaire-9, Columbia-Suicide Severity Rating Scale-Recent, and validated homosexuality-related stigma subscales. Multiple regression analyses were used to identify factors associated with depression, suicidal ideation, and stigma. Results Of the 150 participants, 77% were MSM. PrEP users had significantly lower depression scores compared to non-users (mean difference = 2.16, p < 0.001), while no significant group differences were found in suicidal ideation or stigma subscale scores. Depression severity emerged as the sole significant predictor of suicidal ideation (OR = 2.82, p = 0.028). Stigma dimensions were shaped by unique predictors: perceived stigma was associated with internalized stigma and higher education; internalized stigma was linked to perceived stigma, low community safety, and unemployment; and enacted stigma was predicted by age and perceived stigma but showed inverse associations with discrimination and family pressure. Conclusion PrEP use may reduce depression but does not independently affect stigma or suicidality. Mental health integration, especially depression screening, is crucial in HIV prevention. Addressing stigma with culturally tailored approaches is vital for MSM and TGW well-being in Thailand.