BackgroundAdvanced HIV in young people living with HIV is an increasingly pressing public health issue in sub-Saharan Africa. Despite global progress in early HIV testing and reducing HIV-related deaths, many young people with HIV continue to experience HIV disease progression in sub-Saharan Africa. This study provides an overview of the prevalence, clinical manifestations, and factors associated with advanced HIV in young people seeking medical services in a major hospital in Sierra Leone.MethodsWe used a cross-sectional design to collect data from HIV patients aged 15 to 24 years at a major hospital in Sierra Leone between September 2022 and March 2023. Advanced HIV was defined as (i) CD4+ below 200 cells/mm3 or (ii) WHO clinical stage 3 or 4. Logistic regression models determined the association between observable independent characteristics and advanced HIV. The statistical significance level was set at 0.05 for all statistical tests.ResultsAbout 40% (231/574) of patients were recruited; 70.6% (163/231) were inpatients, and 29.4% (68/231) were outpatients. The mean age was approximately 21.6 years (SD ±2.43). The overall prevalence of advanced HIV was 42.9% (99/231), 51.5% (35/68) of outpatients, and 39.3% (64/163) of inpatients. Age of inpatients (OR, 1.23; 95% CI, 1.00-1.52; p= 0.047) was associated with a higher risk. Female sex (OR, 0.51; 95% CI, 0.28-0.94; p= 0.030), higher education (OR, 0.27; 95% CI, 0.10 – 0.78; p= 0.015), and Body Mass (OR, 0.10; 95% CI, 0.01-0.77; p= 0.028) were at lower risk of advance HIV. Common conditions diagnosed in this population are tuberculosis (13.58%), hepatitis B (6.13%), Kaposi sarcoma (3.07%), and esophageal candidiasis (2.45%).ConclusionWe reported a high prevalence of advanced HIV among young patients in a referral Hospital in Sierra Leone. This emphasises the need to strengthen public health measures and policies that address challenges of access to HIV services.Strengths and limitations of this studyThis is the first study in Sierra Leone and the sub-region to examine the burden of advanced HIV and its predictors in young people living with HIV.Calls for a more targeted approach to addressing gaps in health service delivery for young people living with HIV in Sierra Leone.The study is limited by the unavailability of several laboratory investigations to monitor patient progress.