Background
Preparing adolescents for transition into adult care and supporting their acquisition of self-health care management skills is a critical determinant of their post-transition HIV care outcomes. However, there is a scarcity of research on effective transition strategies. This study explores factors associated with adolescent preparedness for transition into adult care in Cambodia.

Methods
In August 2016, a cross-sectional study was conducted among 223 adolescents living with HIV aged 15–17, randomly selected from 11 antiretroviral therapy clinics, utilizing a structured questionnaire. The level of preparedness was determined using a pre-existing scale, and adolescents were categorized as having a high- or low level of preparedness for transition. Bivariate and multivariate analyses were conducted.

Results
Of 223 adolescents, 55.2% were male, and their mean age was 15.8 years. Overall, 53.3% had a high level of preparedness for transition. As part of the transition protocol, 2.7% had completed a transfer form, 24.7% had a transition case manager, 29.6% had been counselled about the transition, and 19.7% had visited an adult ART clinic. In multivariate analysis, a higher level of preparedness for transition was independently associated with older age (AOR 2.44, 95% CI 1.34–4.46; p = 0.004), family having received social support for their health (AOR 5.32, 95% CI 1.97–14.36; p = 0.001), knowing the kind of treatment they received (ART) (AOR 12.67, 95% CI 2.91–15.19; p = 0.001), trust in friends or family for HIV treatment (AOR 7.82, 95% CI 1.13–8.89; p = 0.008), receiving counseling on transition (AOR 3.17, 95% CI 1.15–8.76; p = 0.03), having a ‘Case Manager’ identified to support them during the preparation process for transition (AOR 3.89, 95% CI 1.08–13.96; p = 0.04), and satisfaction with preparation process for transition in general (AOR 0.35, 95% CI 0.03–0.87; p = 0.01).

Conclusions
A range of individual, social and health system and services factors may determine successful transition preparedness among adolescents in Cambodia. Strengthening implementation of age-appropriate and individualized case management transition at all sites, while creating supportive family, peer, and healthcare environments for adolescent transition is required.