Performance and usability evaluation of the INSTI HIV self-test in Kenya for qualitative detection of antibodies to HIV

BACKGROUND: HIV testing is often undermined by lack of confidentiality, stigma, shortage of counselors and long distances to testing centers. Self-testing has the potential to circumvent these constraints. OBJECTIVE: To determine the performance and usability characteristics of the INSTI® HIV-1/HIV-2 Self-Test. METHODS: The performance evaluation was a cross sectional study and the usability a mixed methods study. For method comparison, Bioelisa HIV-1+2 Ag/Ab test was used as the reference test. When the test results were discrepant, results from Alere Determine™ HIV-1/2 and First Response HIV-1-2 Antibody tests were used for confirmation of status. RESULTS: Sensitivity of the INSTI HIV Self-Test was 98.99% (95% CI 96.05–99.75%), and specificity 98.15% (95% CI 95.63–99.23%). The concordance was therefore 97.27%. A total of 354 participants took part in the usability study. Of those, 343 (98.00%) found instructions for use easy to follow, 330 (94.29%) found the finger prick device easy to use, 303 (86.57%) were confident while performing the test, 342 (97.71%) felt result interpretation was easy, while 304 (86.86%) declared results within the recommended five minutes. Three hundred and forty two (342, 97.71%) were willing to use the test again while 344 (98.29%) would recommend the kit to a sexual partner. None of the 350 participants quit the process at any stage. Three hundred and eighteen (318, 91.12%) participants felt the test needed no further improvement. All 91 lay users correctly identified cartridges that showed positive, negative and invalid results. Only 31 (34.07%) participants correctly identified weak positive dummy test results. CONCLUSION: The excellent performance and usability characteristics of INSTI HIV-1/HIV-2 self-test make the kit a viable option for HIV self-testing. To improve the identification of weak positive results, the manufacturer should indicate on the IFU that even a faint test spot should be interpreted as positive.