Baseline HIV genotypic resistance testing in patients newly diagnosed with HIV: When do we need to consider baseline integrase resistance testing for everyone?

BACKGROUND

We aimed to describe baseline drug resistance in patients newly diagnosed with HIV in Brighton over a 12-year period.

METHOD: As part of a quality improvement project, clinic data were collected for all patients newly diagnosed with HIV between January 2014 and December 2025. Locally, baseline genotypic resistance testing is routinely performed at diagnosis and assessed for resistance to nucleos(t)ide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs). Since 2022, baseline resistance for integrase inhibitors (INIs) has also been performed. Transmitted drug resistance mutations for NRTIs, NNRTIs and PIs were defined according to the World Health Organization (WHO) criteria. Integrase resistance mutations were identified using the Stanford HIV Drug Resistance Database. Extracted data included patient demographics, date of HIV diagnosis, HIV subtype and previous HIV pre-exposure prophylaxis (HIV-PrEP) use.

RESULTS

Three hundred and eighteen individuals newly diagnosed with HIV throughout the study period, of which 312 had a resistance report available for analysis. Overall, baseline drug resistance was found in 38/312 (12%, 95% CI 8.76-16.33). The median age was 37 years (IQR 30-46). 13 (39%) patients were non-UK born and 17 (52%) had a non-B subtype. There were 12 (4%) individuals with NRTI resistance mutations, 13 (4%) with NNRTI mutations and 5 (2%) with PI mutations. Integrase resistance mutations were found in 8/73 (11%) between 2022 and 2025, 3 of whom had no other class resistance. Baseline drug resistance was associated with non-clade B genotypes (OR = 2.79, 95%CI = 1.34-5.79, p = 0.006) and previous HIV-PrEP use (OR = 4.14, 95%CI = 1.66-10.4, p = 0.003).

CONCLUSION

This manuscript identified a number of cases where baseline integrase resistance was identified. These data suggest that more work is needed to establish whether baseline integrase inhibitor resistance testing is warranted in all individuals newly diagnosed with HIV.