Evaluation of HIV-1 drug resistance in newly diagnosed individuals in Italy over the period 2017-2023.

OBJECTIVE

We evaluated the prevalence of HIV-1 drug resistance in newly diagnosed individuals from 2017 to 2023, in Italy.

METHODS

Transmitted drug resistance (TDR) was evaluated by using the HIVdb algorithm (https://hivdb.stanford.edu/), through two different approaches: (1) by considering the complete list of mutations included for the genotypic susceptibility score and (2) by considering only major resistant mutations. Logistic regression analysis was used to estimate the association of TDR with the calendar year.

RESULTS

We analysed 1188 drug-naive individuals diagnosed in Italy between 2017 and 2023 enrolled in the Antiviral Response Cohort Analysis database. Most of them (∼75 %) were males; their median (IQR) age was 40 (30-50) years. Non-B subtypes were found in 43.9 % of participants and significantly increased over time (from 44.2 % in 2017 to 54.8 % in 2023, P = 0.008). TDR prevalence was 29 %, driven by non-nucleoside reverse transcriptase inhibitor resistance (19.4 %). Rates of nucleoside reverse transcriptase inhibitors, protease inhibitors, and integrase strand transfer inhibitors resistance were 4.7 %, 4.4 %, and 5.1 %, respectively, with no significant temporal trends. When only major resistant mutations were considered, TDR prevalence was definitively lower (15.8 %), primarily driven by non-nucleoside reverse transcriptase inhibitor mutations (11.8 %). Rates of resistance for major nucleoside reverse transcriptase inhibitors, protease inhibitors, and integrase strand transfer inhibitors were 4.6 %, 1.7 % and 0.7 %, respectively. Resistance to two or more drug classes was rare (1.9 %). No association of major TDR within the calendar year was found, except for 2023 (AOR: 2.33 [1.14-4.74], P = 0.019).

CONCLUSIONS

Over the period 2017-2023, the HIV-1 TDR appeared generally stable in Italy. However, the increased prevalence of major TDR in 2023 confirms the importance of continuous TDR surveillance in newly diagnosed individuals to inform clinical practice.