Outpatient Testing for HIV in Italy, 2018-2023-Preliminary Data

Abstract

HIV testing is crucial towards the control of the Acquired Immune Deficiency Syndrome (AIDS) epidemic. Monitoring trends of human immunodeficiency virus (HIV) testing over time may help interpret the incidence of new HIV diagnoses and effectiveness of HIV testing strategies. We started a research project aimed at assessing testing rates for HIV infection among Italian outpatients in 2018-2023. Numeric data for screening, confirmatory, and monitoring tests obtained by a national register were compared with the numbers of adult residents, newly diagnosed HIV infections, and patients undergoing treatment. The number of screening tests declined from 1,133,377 in 2018 to 889,972 in 2020 and increased to 1,096,822 in 2023. HIV-RNA tests showed a similar pattern, whereas confirmatory immunoblots did not vary significantly over time. The ratio of screening tests to adult residents was higher in North-West (2.87%) and North-East (2.31%) Italy compared to South Italy and the islands (1.47%), indicating that screening should be enhanced in the latter area. We observed differences between the ratio of screening tests and the incidence of newly diagnosed HIV infections by geographic area. Discrepancies in the number of screening and confirmatory tests needed for each new diagnosis suggest repeated testing on people already diagnosed and possible data reporting issues. The monitoring of HIV screening tests at the national and regional levels can provide essential data to interpret trends in HIV epidemiology and plan relevant testing strategies over time.

Keywords: HIV diagnosis; HIV epidemiology; HIV testing; diagnostic algorithms; population screening; supplemental tests.

Figure 1

Schematic workflow of the HIV diagnostic algorithm most frequently adopted in Italy. Starting from reactivity by any screening test (top left), the large blue arrows indicate a sequential testing approach (supplemental testing by HIV-specific immunoblots and nucleic acid amplification methods, if needed), and the red arrows indicate the final step according to the results of supplemental testing. The black arrows indicate an alternative first step for confirmation (second screening test) adopted in some areas.

Figure 2

Number of HIV screening tests by geographical area and year of testing, Italy 2018–2023.

Figure 3

Rates of HIV screening per adult residents × 100 by area of residence, Italy, 2018–2023.

Figure 4

HIV screening rate in adult residents (number of screening tests/adult residents × 100) by geographical area, Italy, 2018–2023. North-West Italy: dark green; North-East Italy: green; Central Italy: light green; South Italy and the islands: pale green.

Figure 5

Temporal trend of the number of HIV screening tests (left Y axis) and the number of new HIV diagnoses (right Y axis); Italy, 2018–2023.

Figure 6

HIV screening rate × 100 adult residents (blue bars) and HIV incidence of NHD x 100,000 adult residents (dotted line) by geographic area, Italy, 2023.