Objective To understand the epidemiological characteristics and late detection of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in the Xizang from 2015 to 2024, and provide evidence for the development of targeted prevention and control strategies.

Methods Data of newly reported HIV/AIDS cases in Xizang between 2015 and 2024 were collected through China Disease Prevention and Control Information System. The cases with the first recorded CD4 cell count < 350 cells/μL within six months after HIV diagnosis or being detected in an AIDS-defining event or died within six months of HIV diagnosis without prior CD4 cell count testing were defined as late-detected cases. Univariate analysis was performed by using χ² test, multivariate analysis was conducted by using logistic regression model, and Joinpoint regression model was used to analyze the temporal trend of the late-detection proportion.

Results From 2015 to 2024, a total of 1,414 HIV/AIDS cases were reported in the Xizang, in which 556 (39.32%) were classified as late detected cases. The demographic and epidemiological characteristics of the cases indicated that the male to female ratio was 1.55:1, 75.46% were aged 25–50 years,31.26% were farmers/herdsmen, 52.40% were married,73.06% were Tibetan, 26.66% had college degree or higher, 64.85% were detected by medical institutions, 89.25% were infected by heterosexual transmission, 67.89% were permanent residents, 75.46% had Tibetan household registration, 9.83% had history of sexually transmitted infection and 48.51% were reported in Lhasa. Annual reported case count increased from 89 in 2015 to 275 in 2024. Joinpoint regression analysis confirmed an overall upward trend with an average annual percent change (AAPC) of 12.04% (P<0.05). Univariate analysis indicated that the gender, age, occupation, ethnicity, transmision route, household registration and area specific differences in late-detection of HIV/AIDS cases were significant (P<0.05). Multivariate Logistic regression analysis revealed significantly higher risk for late detection of HIV/AIDS in people aged ≥25 years (age 25–50 years: OR=1.831, 95% CI: 1.285–2.609, age >50 years: OR=2.049, 95% CI: 1.240–3.386).

Conclusion The prevalence of HIV/AIDS in Xizang remained at low level but showed a persistent upward trend during 2015–2024, with a late-detection rate of 39.32%. Age ≥25 years was a significant independent risk factor for the late diagnosis.