Abstract Body

ART achieves viral suppression in the majority of HIV infected patients in low and middle-income countries. WHO guidelines recommend annual viral load (VL) monitoring with confirmatory VL testing in case of a VL ≥1000 copies/mL (c/mL), and switch to second-line ART without resistance testing if virological failure (VF) is confirmed. However, challenges exist regarding clinical follow-up of VL results, prompting discussion around the criteria for VF and switch to second-line ART.

Patients from 19 urban and 38 rural South African HIV treatment sites were studied. Adult patients on first-line ART for ≥20 weeks and with ≥1 VL performed ≥20 weeks after start of ART were included. Proportions of viremia ≥1000 c/mL, confirmed VF (>1 VL ≥1000 c/mL) on first-line ART, likelihood of switch to second-line ART, and resuppression on first-line ART were analyzed.

69,454 patients were included. 20.7% of patients (14,380/69,454) had ≥1 VL ≥1000 c/mL during 209,638 patient years of first-line ART. After 1 year of ART, 88.3% of patients achieved viral suppression <1000 c/mL. Patients with a VL ≥1000 c/mL were more often male (35.6% vs 31.2%), younger (34.9 vs 36.0 years), and had a lower baseline CD4-count (159 vs 193 cells/uL). Of 9,351 patients with a VL ≥1000 c/mL and ≥1 subsequent VL result during first-line ART, VF was not confirmed in 44.8% (4,186/9,351) of patients, with 90.4% (3,785/4,186) of these patients achieving resuppression <50 c/mL without switch to second-line ART. In patients with confirmed VL ≥1000 c/mL, resuppression without switch occurred in 15.9% (581/3,649), but they remained at increased risk of subsequent VF. Median time between first detection of a VL ≥1000 c/mL and confirmation of VF was 30 weeks [IQR: 17 – 53]. Median time between first detection of VF and switch was 67.7 weeks [35 – 124].

In this large cohort of patients on first-line ART monitored according to WHO guidelines, viral resuppression occurred in just under half of cases after a single VL ≥1000 c/mL, and in a considerable number of cases after VF was confirmed. Confirmation of VF and switch to second-line ART was performed after significant delay, allowing for prolonged episodes of viremia and potential onward HIV transmission. These data confirm the relevance of timely confirmatory VL testing, and suggest that once virological failure is confirmed, diagnostic tools to discriminate between non-adherence and loss of drug activity may prevent unnecessary switches to second-line ART.