Utility of interrupting antiretroviral treatment before HIV drug resistance testing in patients with persistently detectable low-level viremia

The HIV Virologic Outcomes of Different Interventions Among Treatment-Experienced Patients With 2 Consecutive Detectable Low-Level Viremia

BACKGROUND

Approaches to treatment-experienced HIV-infected patients with persistent low-level viremia are limited by current commercial resistance genotyping assays when the viral load (VL) is <500 copies/mL. The best intervention to achieve virologic suppression in this population is unclear.

METHODS

This is a case control retrospective chart review study of 149 HIV-infected patients with a VL of 50 to 1000 copies/mL. Patients were in either regimen unchanged group or intervention group (intensification of regimen or switch without guidance from resistance testing). End point was VL < 100 copies/mL.

RESULTS

At 6 months post change, 30.8% of patients with intervention versus 36.6% with no intervention achieved a complete virologic suppression. There were no statistically significant differences between these 2 groups (P = .254). The majority of patients without regimen change eventually progressed to complete virologic failure.

CONCLUSION

Patients with persistent low levels of viremia are likely to progress to have virologic failure. This supports the adoption of a more proactive approach to treatment and more sensitive technique to identify drug resistance.

HIV Drug Resistance Profiles and Clinical Outcomes in Patients with Viremia Maintained at Very Low Levels

We describe an observational study of clinical, virologic and drug resistance profiles in HIV-positive antiretroviral adherent subjects with stable low level viremia (LLV) 50-1,000 copies/mL for more than 12 months. Subjects were followed from time of first detectable viral load (VL). In total, 102 episodes of LLV were detected among 80 individuals. The median (mean, range) HIV copy number at genotyping was 250 (486, <50-3900) copies/mL after 14 (17.9, 0-58) months of LLV. Few patients maintained LLV for the entire 9 year period of observation, with half (52%) experiencing viremic progression following a stable period of LLV either spontaneously or after treatment interruption or failed regimen intensification. In the setting of prolonged periods of sustained LLV, mean duration 22 (range 8 - 106) months, drug resistance (DR) was almost universal. Resistance to ≥1 on-treatment drugs was defined in 97% of specimens and DR to all drugs in the treatment regimen in over half of all patients. Evolution of DR mutations during the period of LLV was observed in 20/28 (71%) subjects with specimens available for follow-up testing. This evolution was associated with viremic progression to levels >1000 copies/mL (p=0.03). Our data suggest that DR present in patients with LLV is likely to impact long term clinical outcomes, highlighting the importance of optimizing techniques to detect the presence of drug resistant HIV in the setting of LLV and the need for larger prospective studies to assess the emergence of DR in the setting of sustained LLV and the impact of this DR on treatment outcomes.