HIV Diagnostic Algorithms in A Resource-Limited Setting: A Comparative Study
Fasakin KA *
Department of Medical Laboratory Science, Afe Babalola University, Ado-Ekiti, Nigeria.
Ajayi OD
Sahara Biomedix, Lagos, Nigeria.
Ibijola AA
Department of Haematology & Blood Transfusion, Afe Babalola University, Ado Ekiti, Nigeria.
Adeniyi AA
Department of Obstetrics and Gynaecology, Afe Babalola University, Ado Ekiti, Nigeria.
Ajetunmobi WA
Department of Paediatrics, Afe Babalola University, Ado Ekiti, Nigeria.
Ajetunmobi OA
Department of Family Medicine, Afe Babalola University, Ado Ekiti, Nigeria.
Adewara OE
Department of Obstetrics and Gynaecology, Afe Babalola University, Ado Ekiti, Nigeria.
Bakare A
Department of Obstetrics and Gynaecology, Afe Babalola University, Ado Ekiti, Nigeria.
Oyegue BE
St. Vincent Private Hospital, Merrion Road, Dublin 4, Ireland.
*Author to whom correspondence should be addressed.
Abstract
Background: Adoption of appropriate HIV testing algorithm is essential for quality HIV diagnostic results. Whether rapid enzyme immunoassay (rEIA) or combination of rapid enzyme immunoassay and enzyme-linked immunosorbent assay (rEIA-ELISA) alternative confirmatory algorithm is enough to make accurate HIV diagnosis has been a subject of controversies. Recent evaluation of national algorithm for HIV testing presented some discrepancies in results. Again, current guideline prescribed discontinuity of Western blot supplemental test and its replacement with Geenius HIV-1/ HIV-2 differentiation test followed by nucleic acid testing. The objective of this study is to compare HIV-1 testing algorithms using ELISA-NAT algorithm as the gold standard for HIV-1 diagnosis, and rEIA-Western blot and ELISA-Western blot as alternative confirmatory algorithms for HIV-2 diagnosis.
Methods: This is a comparative study involving a cohort of 173 (98.9%) HIV-positive subjects and two (1.1%) HIV-negative subjects initially diagnosed on the basis of rEIA algorithm. Plasma samples separated from ethylene diamine tetra-acetic acid anticoagulated blood were used for further analyses. Fourth generation HIV antigen-antibody kit was used for further testing to make up rEIA-ELISA algorithm. Analyses with Western blot 1 and 2 assays were done as supplemental tests to make up alternative rEIA-Western blot and ELISA-Western blot confirmatory algorithms. Research subjects were further tested for HIV-RNA under PEPFAR plan. The sensitivity, specificity, positive predictive value and negative predictive value of algorithms were compared using the descriptive statistics of the SPSS version 17.
Results: The HIV testing analyses showed 100% sensitivity, specificity, positive predictive value and negative predictive value from algorithm to algorithm especially for HIV-1 diagnosis. Use of combined ELISA-NAT confirmatory algorithm validated outcomes of rEIA-Western blot and ELISA-Western blot alternative confirmatory algorithms for HIV-1 diagnosis. Among HIV-1 positive samples tested, 50.0-60.7% HIV-2 Western blot indeterminate result was obtained and 7.1-10.7% HIV-1/HIV-2 co-infections were observed.
Conclusion: The rEIA or national algorithm and its combination with enzyme-linked immunosorbent assay are reliable alternative confirmatory algorithms for the diagnosis of established HIV-1infection in resource-limited settings but not for HIV-2. Diagnosing acute HIV infection with current algorithm is limited and still require further review.
Keywords: Enzyme immunoassay, enzyme-linked immunosorbent assay, Western blot, indeterminate results, algorithm, sensitivity, specificity