Evaluating the time of HIV infection, diagnosis and treatment delays based on HIV notification data in Northwest China, 2008–19

Background. Timely diagnosis and treatment are crucial for reducing HIV transmission; therefore, estimating the time from HIV infection to antiretroviral therapy (ART) initiation becomes particularly important for people living with HIV. Methods. We used a well-characterised CD4 depletion model to estimate the time from HIV infection to initiation of ART and the rate of delayed HIV diagnosis (infection to diagnosis >1 year) and treatment initiation (diagnosis to treatment >1 year), based on HIV notification data for adults (aged ≥18 years) in Xi’an city, China, during 2008–19. Results. Overall, 7402 reported HIV diagnoses were included. We estimated more than two-thirds of HIV infections remained undiagnosed (66.1%, 9489/14 345). The estimated proportion of HIV diagnoses that were delayed (>1 year) was 80.3% (5941/7402) during 2008–19, and it increased from 72.7% (32/44) in 2008 to 83.5% (908/1088) in 2019. In contrast, the proportion of cases with delayed treatment (>1 year) was 13.1% (971/7402) during 2008–19, and it reduced from 75.0% (33/44) in 2008 to 1.5% (16/1088) in 2019. The estimated median time from HIV infection to diagnosis increased from 5.05 (IQR, 0.27–8.15) years to 5.81 (IQR, 2.31–10.28) years, whereas the time from diagnosis to ART initiation reduced from 3.06 (IQR, 1.01–5.20) years in 2008 to 0.07 (IQR, 0.04–0.12) year in 2019. Conclusions. Early treatment after diagnosis has significantly improved, but timely diagnosis of HIV infections may still require further improvement. The estimated proportion of undiagnosed HIV cases remains high in 2019 in Xi’an city and is likely to impede effective control.