1573. Viral Blips While on Antiretroviral Therapy are Associated with Virologic Failure

Abstract Background Blips in HIV viral load (VL) while on antiretroviral therapy (ART) are of unclear clinical significance. In this study, we examined the association between blips and virologic failure (VF). Methods We used data from the US Military HIV Natural History Study (NHS) cohort. Included participants were diagnosed with HIV after 2006, had been on ART for ≥ 6months, and had ≥3 VLs recorded and measured using an assay with a lower limit of detection of < 50 copies/mL. VF was defined as two consecutive VLs ≥ 200 copies/mL spanning 90 days or a single VL ≥1000 copies/mL. Blips were defined as VL of 51-999 copies/mL, that were preceded and followed by a VL ≤ 50 copies/mL and were differentiated by magnitude as low-level (VL 51-199 copies/mL) or high-level (200-999 copies/mL). Detectable VLs that did not meet criteria for VF or blips were grouped as low-level viremia (LLV; 51-199 copies/mL), and higher low-level viremia (hLLV; 200-999 copies/mL). Cox proportional hazards models adjusted for demographic characteristics, time updated CD4 counts, ART, and viral load were used. Hazard ratios and 95% confidence intervals are presented. Results A total of 988 participants (median age 34.1 years, 96.7% male, 41.7% African American) were included, of which 55 (5.6%) experienced VF (Table 1). While 191 participants (19.3%) experienced blips, it was the highest VL status in 146 (14.8%) (Table 2). Having blips and low-level viremia was associated with increasing hazard of VF, graded by type and level of viremia (low-level blip 1.86 [1.10 – 3.14]; high-level blip 3.56 [1.13 – 11.18]; LLV 4.10 [3.06-5.51]; hLLV 10.51 [6.28-17.61]. Other factors associated with VF were African American race and higher VL at ART initiation. Whereas higher CD4 counts, and use of integrase strand transfer inhibitors (relative to Non-Nucleoside Reverse Transcriptase inhibitors) were protective (Table 3). Conclusion Detectable viremia, including blips, are associated with an increased risk of VF. The magnitude of the viremia appears important with dose-response-type impact (i.e., viral loads >200 copies/mL having a greater hazard of VF). These findings suggest that individuals with viral blips at a minimum should undergo evaluation for medication adherence and may benefit from more frequent VL monitoring. Disclosures All Authors: No reported disclosures