Background: New point-of-care (POC) HIV molecular diagnostic tools could fundamentally alter early infant HIV diagnosis (EID) and management in resource-limited settings by reducing the time to initiation of antiretroviral therapy and promoting retention in care. However few technologies have been independently evaluated and data on new technologies are urgently required.
Methods: We investigated the analytic performance of the Alere q HIV1/2 POC assay in the laboratory setting by comparing the result with the local standard-of-care (SOC), Roche CAP/CTM HIV-1 qualitative PCR. Testing was conducted on routinely collected EID samples received at the public sector reference lab in Cape Town, South Africa between November 2013 and September 2014. Cycle threshold (CT) values from the Roche systm were used as measures of relative quantification.
Results: A total of 1065 HIV-exposed infants (median age, 47 days) undergoing SOC testing with final infant status available were included in the study. The first Alere q test resulted in an error for 60 samples (6%) but 70% of all errors were resolved with a second Alere q test. The performance of Alere q is shown in Table 1. Excluding errors, overall specificity was 100% (lower bound of 95% confidence interval [CI], 99.5%) and sensitivity was 96.8% (95% CI, 93.2%-98.8%). False negative samples had a median CT value of 32.8 on the SOC assay, higher than both the true positives (median CT, 24.2; p<0.001) and errors (median CT, 21.0; p<0.001). When analysis was restricted to specimens from newborns tested at <3 days of age, specificity remained high (100%) but sensitivity decreased to 91.6%.
Conclusions: These results demonstrate good performance characteristics of this POC assay used for EID in the laboratory setting. While POC testing for EID may have particular utility in the context of birth testing within delivery facilities, the lower sensitivity of tests conducted within 3 days of birth require attention. Higher CT values were observed for false negative results, possibly due to lower levels of circulating virus during early infection. Further research is required to determine whether similar results can be achieved when this technology is implemented in clinical care settings, including for in birth testing.
Table 1. Performance of Alere q point-of-care test compared to Roche CAP/CTM HIV-1 qualitative PCR for early infant diagnosis, based on 1065 children with final infant HIV status available.