In the current study, the researchers sought to establish whether a convenient, non-invasive HIV test that uses oral fluid was accurate compared with using the same test with blood-based specimens.
The systematic review and meta-analysis compared the accuracy of OraQuick Advance Rapid HIV-1/2 test using oral fluid versus blood-based specimens among adults at risk of HIV. The study authors searched five databases of published work and databases of five key HIV conferences. Diagnostic accuracy was assessed with bivariate regression analysis, and positive predictive values (PPVs) in high- and low-prevalence settings were computed with Bayesian methods.
In a direct comparison of studies, the researchers identified a pooled sensitivity about 2 percent lower in oral (98.03 percent, 95 percent CI 95.85-99.08) than in blood-based specimens (99.68 percent, 97.31-99.96), but similar specificity (oral 99.74 percent, 99.47-99.88; blood 99.91 percent, 99.84-99.95). Negative likelihood ratios were small and similar (oral 0.019, 0.009-0.040; blood 0.003, 0.001-0.034), but positive likelihood ratios differed (oral 383.37, 183.87-799.31; blood 1105.16, 633.14-2004.37). Although in high-prevalence settings PPVs were similar (oral 98.65 percent, 95 credible interval 85.71-99.94; blood 98.50, 93.10-99.79), in low-prevalence settings PPVs were lower for oral (88.55 percent, 77.31-95.87) than blood (97.65 percent, 95.48-99.09) specimens.
"Although OraQuick had a high PPV in high-prevalence settings in oral specimens, the slightly lower sensitivity and PPV in low-prevalence settings in oral specimens should be carefully reviewed when planning worldwide expanded initiatives with this popular test," concluded Pant Pai and colleagues.
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