Hiv Testing Uptake and Delayed Diagnosis in Underserved Communities: A Scoping Review of Epidemiological and Health-System Determinants

Late diagnosis of human immunodeficiency virus (HIV) infection remains common, and underserved communities have unequal opportunities to be tested. To map epidemiological, sociodemographic, behavioural, structural and health-system determinants of HIV testing uptake and delayed diagnosis among underserved communities and to compare determinants across the two outcomes. This scoping review followed Joanna Briggs Institute guidance and the PRISMA extension for scoping reviews. Peer-reviewed sources published 2021–2026 were identified through a web search engine and citation chasing (20 October 2026); searches were not executed in bibliographic databases. Of 53 reports assessed for eligibility, 26 sources were included (22 primary studies, 4 reviews) from sub-Saharan Africa, Europe, Asia and North America. Testing uptake was lower among men, adolescents and young adults, less educated people, poorer households, communities with high illiteracy, and people reporting stigma or discriminatory attitudes. Reported proportions of late diagnosis ranged from 17.6% to 67.9%, but these figures are not directly comparable because definitions (CD4 threshold, AIDS diagnosis and time window) and study populations differed. In contrast to low testing uptake among younger people, delayed diagnosis was linked mainly to older age, heterosexual transmission, migration and missed testing opportunities at earlier health-care contacts. Determinants of uptake and delay overlap but are not identical. Test offers guided by clinical indications rather than perceived risk alone, database-based replication and common outcome definitions are needed.