Background: Achieving the 3rd 90 demands sustained anti-retroviral therapy (ART) and routine viral load (VL) monitoring for people living with HIV (PLHIV) to ensure viral suppression (i.e. VL< 1,000 copies(c)/ml). In Zambia, ART-treated PLHIV with VL ≥1,000 c/ml enter a complex “failure” cascade requiring enhanced adherence counseling (EAC), follow-up VL testing (within 90 days), and possible switch to second-line ART. Here, we report the first “failure” cascade from Zambia for a large PEPFAR-funded HIV treatment cohort supported by the Centre for Infectious Disease Research in Zambia (CIDRZ).
Methods: We abstracted routine data from electronic health records for all PLHIV >18 years who accessed ART services in 74 CIDRZ-supported facilities across 3 Zambian provinces and had ≥1 documented VL between January 1, 2016?September 30, 2018. We describe the failure cascade using summary statistics.
Results: Figure 1 depicts patient flow in the failure cascade. Of 118,266 patients with a documented first VL, 12.1% (n=14,291) were unsuppressed. Of those, 9.2% had a follow-up VL drawn within 90 days, at a median of 266 days (IQR: 174-402). Time to first follow-up VL did not differ by gender (p=0.23), but was faster for adolescents (18-24 years) compared to older (>25 years) PLHIV (p< 0.001). Half of patients with a follow-up VL achieved viral suppression (n=2,519, 50.6%), while 49.4% (n=2,459) experienced virological failure (i.e. two consecutive unsuppressed VLs). Of 2,459 with virological failure, only 720 (29.3%) switched to second-line ART per guidelines.
Conclusions: For ART-treated PLHIV with an unsuppressed routine VL in Zambia during the evaluation period, we observed gaps with provision of follow-up VL testing and substantial testing delays. Of those with virological failure, only about one-third receive second-line ART. New differentiated service delivery models are needed that offer unsuppressed patients expedited clinical and laboratory services, including EAC, follow-up VL and HIV genotype testing, and ART regimen change.

Figure 1. Patient Flow in the HIV Viral Load Failure Cascade
[Figure 1. Patient Flow in the HIV Viral Load Failure Cascade]