Feasibility of a targeted, very early infant HIV diagnosis algorithm in a resource-limited setting

Abstract

Background: Studies evaluating accuracy in HIV testing in high HIVprevalencecountries remain limited. This studyaimed toassess the overall accuracy level and factors associated with accuracy in HIV rapid testing in Zambia. Methods & Materials: Accuracy was investigated among rural andurbanHIV testing sites participating in twoannual nationalHIV proficiency testing (PT) exercises conducted in 2009 (PT1; n=282) and 2010 (PT2; n=488). Testers included lay counselors, nurses, laboratory personnel and others. PT panels consisted of five serum samples conditioned into dry tube specimens (DTS) issued to testing sites by the national reference laboratory (NRL). Individual test site accuracy level was assessed by comparison of reported results to the expected PT panel results. Non-parametric rank tests and multiple linear regression models were used to assess variation in accuracy between tester groups and to examine factors associated with accuracy respectively. Results: The overall accuracy level was 93.1% and 96.9% in PT1 and PT2 respectively. Differences in accuracy were seen between the tester groups in the first exercise in 2009, with laboratory personnel being more accurate than non-laboratory personnel, while in 2010 no differences were seen. Comparing the two exercises, an improvement in accuracy level was seen among all non-laboratory tester groups, i.e. lay counselors (96.5% from 89.9%), nurses (96.1% from 93.5%) and others (98.5% from 95.0%), while performance remained stable among laboratory personnel (98.7% vs 98.7%). In both PT exercises, lay counselors and nurses had more difficulties interpreting results, with more occurrences of false negative, false positive and indeterminate results. Adherence to the national HIV testing algorithm and having received the standard HIV rapid testing training were associated with accuracy. Conclusion:The study showsan improvement in accuracyoverall and particularly among lay counselors from the first PT exercise to the next. Average number of incorrect test results per 1000 tests performed was reduced from 69 to 31. Further improvement is needed however, and the national HIV proficiency testing system seems to be an important tool in this regard which should be continued and needs to be urgently strengthened.