Background Our outreach HIV Point of care testing (POCT) programme changed from 4th generation testing to 3rd generation POCT kits in August 2014, which led to a significantly quicker turnaround time for results and greater convenience for both outreach staff and patients. We continued to confirm all POCT serology by conventional laboratory testing.
Aims To compare 3rd and 4th generation POCT in clinical practice and review the need for laboratory confirmation of all samples.
Methods The INSTI™ HIV-1/HIV-2 Antibody Test was used for POCT testing at a city centre outreach service from August 2014 until July 2015. All samples were also tested in parallel, in real-time, by standard laboratory tests for HIV. Results were compared retrospectively.
Results POCT was provided for 399 patients. 31 patients were excluded. Of the remaining 368 patients, there were 6 true positive results (1.6%) and no false-negatives or false-positives. By contrast, our previous evaluation of Alere Determine™ 4th generation testing, with a sample size of 367, found 3 true positives (0.8%); 2 false positives (0.6%); and 3 false negatives (0.8%), leading to negative predictive value 99.2%; positive predictive value 60%; sensitivity 50%; specificity 99.4%. This was a significant underperformance in clinical practice compared with advertised values.
Discussion INSTI™ is outperforming Alere Determine™ in our local experience. We intend to continue using 3rd generation POCT in our outreach programme. Given INSTI™’s performance, the question now raised is can we consider moving away from carrying out backup serology in all cases?