True and false positive HIV point of care test results in a prospective multinational study of at-risk African women : implications for large-scale repeat HIV testing in HIV prevention programs

Abstract

BACKGROUND :

Accurate HIV point of care testing is the cornerstone of prevention and treatment efforts globally, although false (both negative and positive) results are expected to occur. SETTING :

We assessed the spectrum of true and false positive HIV results in a large prospective study of HIV incidence in African women using 3 contraceptive methods tested longitudinally in Eswatini, Kenya, South Africa, and Zambia. METHODS :

HIV serologic testing was conducted quarterly using 2 parallel rapid HIV tests. When one or both tests were positive, additional confirmatory testing was conducted, including HIV enzyme immunoassay (EIA) and RNA. RESULTS :

A total of 7730 women contributed 48,234 visits: true positive results occurred at 412 visits (0.9%) and false positives at 96 visits (0.2%). Of 412 women with HIV seroconversion, 10 had discordant (ie, 1 negative and 1 positive) rapid tests and 13 had undetectable HIV RNA levels. Of 62 women with false positive rapid HIV results, most had discordant rapid testing, but 6 (9.7%) had dually positive rapid results, and 4 (6.5%) had false positive or indeterminate EIA results. The positive predictive value of dual positive rapid results was 98.3%. CONCLUSIONS :

Although most rapid test results were accurate, false positive results were expected and occurred in this population of initially HIV seronegative individuals tested repeatedly and prospectively. When HIV infection occurred, not all cases had textbook laboratory results. Our findings highlight the importance of confirmatory testing, particularly for individuals undergoing repeat testing and in settings where the point prevalence is expected to be low. TRIAL REGISTRATION :

ClinicalTrials.gov number NCT02550067.