Discussion
virologic failure, VF, DSD
SEMI
Children, adolescents and young adults living with HIV (CALWH) in sub-Saharan Africa have high rates of mortality and morbidity due to disproportionately lower rates of VL suppression, reduced adherence and low rates of switching to second and third-line regimens [Clinic-based assays and point of care (POC) VL testing may result in more efficient and rapid drug switching. A recent study by Nicholas, et al (2019) in rural clinics in Malawi demonstrated that POC testing with SAMBA, reduced TAT for VL results and time to drug switching [Although the OR point estimate for the weighted model is slightly greater than 1, and less than 1 in the ITT missing VL = failure model, the overall result is the same, there is no significant difference in VL suppression between the two arms. The main reason for the different direction of the effect of SAMBA compared to SOC might be because of the assumption of treating all missing VL as failure. Since SOC has a higher proportion of missing 12 month VL compared to SAMBA (13% vs. 9% per protocol and 25% vs 21% per ITT), the suppression rate in the SOC arm is almost the same compared to the SAMBA arm (81% vs. 80% respectively). However, this assumption does not effectively change the conclusions of the study. Studies of assays of lower level VL thresholds (>20–999 copies/ml) suggest that the WHO-recommended ≥1,000 copies/ml threshold may underestimate virologic failure [We found that the SAMBA-II semi quantitative assay is well suited to identifying VL failure at the ≥ 1,000 copies/ml threshold and was simple to manage in a rural hospital setting with limited power, internet access and telecommunication. New clinic-based assays and POC technologies offering rapid quantitative POC VL at lower thresholds [Access to InSTI-based-third-line treatment has been restricted by the requirement for genotyping and the demonstration of major PI resistance mutations as prerequisites for consideration of InSTI-based, third-line treatment and darunavir-based regimens. Here we found that only 4/24 (17%) second-line failures had major PI resistance despite persistent VF as described in urban Zimbabwe [Care at Chidamoyo provides long-term retention and support through community-based counselling and ART [Strengths of our study include the use of relatively large sample of participant data from a largely decentralized HIV programme in Zimbabwe and that the clinic-based SAMBA VL testing was successfully performed by the clinic medical team at the Chidamoyo clinic. Sustaining long-term ART and VL testing in rural Zimbabwe in CALWH requires innovative approaches to DSD to improve adherence, retention in care and faster drug switch [The major limitation of our study includes the fact that, the clinic-based SAMBA VL testing did not help in rapidly facilitating adherence counselling and faster regimen switch after identifying VF, due to the bimonthly visit programme at CCH. Another limitation includes the high lost to follow up resulting in only 89% (347/390) of VL tests being used in the final analysis, possibly underestimating VL testing coverage. The power of the study to be able to determine a difference between the clinic-based SAMBA assay and SOC VL testing was also limited due to relatively good rates of viral suppression at baseline and limited duration of follow-up.