Chronic and early antiretroviral therapy impact HIV serological assay sensitivity leading to more false negative test results in HIV diagnosis.

: This retrospective study evaluated the reactivity of three HIV confirmatory assays (INNO-LIA®, GeeniusTM and MP) and seven HIV rapid tests, on samples from two different study populations in Belgium. For the early-treated cohort (83 HIV-1 adult patients treated within 3 months after infection), HIV-1 diagnosis was not obtained in at least one confirmatory assay in 12.0% (10/83) and in an HIV rapid test in 31.3% (26/83). Confirmation assay sensitivities ranged 87.5-95.2%, whereas rapid test assay sensitivities ranged 75.9-100%. The time to treatment initiation or the length of time on treatment did not have a statistical influence on the probability to obtain a false negative test result. The fastest reversion was demonstrated after 4 months of treatment. Among the long-term treated cohort (390 HIV-1 patients with ≥9 years of undetectable viral load), false-negative test results were found in at least one HIV confirmatory assay for 2.1% (8/390) of the patients and in a HIV rapid tests for 4.9% (19/390). Confirmation assay sensitivities ranged 98.1-99.5%, whereas rapid test sensitivities ranged 96.2-100%. Longer treatment increased non-reactivity of the HIV rapid tests (p=0.033). Undetectable viral load decreases the sensitivities of HIV diagnostic tests and further monitoring of the performance of serological assays is advised.