Application Evaluation Of LAg-Avidity EIA For Detecting HIV Incidence

BackgroundBED-CEIA is a widely used laboratory method for detecting HIV incidence in China, however, this method has many factors and the false-recent rate (FRR) is high. Recently, limiting antigen avidity enzyme immunoassay (LAg-Avidity EIA) has been developed to solve these problems, and studies showed FRR was only0.2%among AIDS. Meanwhile, performance evaluation in laboratory demonstrated the FRR of Lag-Avidity EIA was0.39%among established HIV infections in China and didn’t subject to the impact of CD4count. Compared with the BED-CEIA, LAg-Avidity EIA had many advantages, can made the estimation of HIV incidence more reliable as well.Objectives1. To evaluate the stability and repeatability of LAg-Avidity EIA in field application.2. To compare the FRR between LAg-Avidity EIA and BED-CEIA.3. To compare the proportions and correlates of recent HIV infections among newly reported HIV/AIDS cases in field application between LAg-Avidity EIA and BED-CEIA.Methods1. Analyzed the results of internal control panel samples between two different laboratories within the same operator, and then calculate the level of consistency for LAg-Avidity EIA. 2. Analyzed the results of initial and confirmatory tests, and then calculate the level of consistency for LAg-Avidity EIA.3. Analyzed the mean, standard deviation and coefficient of variation (CV) of optical density (OD) and normalized OD (ODn) for NC, CAL, LPC, and HPC from57individual plates that have been tested by LAg-Avidity EIA in Dehong HIV confirmatory laboratory.4.653samples from known long-term infections were tested by both LAg-Avidity EIA and BED-EIA, then compare and calculate the FRR.5. All available serum samples of newly reported HIV/AIDS cases during2009-2011period in Dehong prefecture, were tested by both LAg-Avidity EIA and BED-EIA, then compare the propotions and correlates of recent HIV infections between the two methods for detecting HIV incidence.6. Data were analyzed by SPSS17.0and STATA10.0, statistic methods including chi-square test, comparison of two rates and logistic regression.Results1. The level of concordance between two different labs within the same operator was quite high (R=0.9967).2. A total of190samples were confirmed after initial screening by LAg-Avidity EIA, and the correlation coefficient between the results of initial and confirmatory tests was about0.90.3. The CV of OD for CAL, LPC and HPC were lower than20%, then after normalization by CAL, the CV of ODn for LPC and HPC were reduced to about15%.4. The FRR of LAg-Avidity EIA and BED-EIA were1.07%(7/653)(95%CI:0.28%-1.86%) and5.82%(38/653)(95%CI:4%-7.61%), respectively.5. The proportion of recent HIV infection among newly reported HIV/AIDS cases tested by Lag-Avidity EIA during2009-2011were4.1%(58/1401),4.9%(61/1250) and3.9%(57/1466), respectively. 6. The proportion of recent HIV infection among newly reported HIV/AIDS cases tested by BED-CEIA during2009-2011were12.6%(176/1401),11.8%(148/1250) and10.9%, respectively.Conclusions1. The performances of Lag-Avidity EIA in term of repeatability and stability were excellent in field application; there were special requirements for experimental condition and operator quality. Further standardize laboratory operations and strengthen personnel training are needed to further improve the detection accuracy.2. The FRR of Lag-Avidity EIA was significantly less than BED-CEIA(p<0.001), so Lag-Avidity EIA is more specific than BED-EIA.The proportion of recent HIV infection among newly reported HIV/AIDS cases tested by Lag-Avidity EIA during2009-2011were significantly lower than BED-CEIA, so the results of Lag-Avidity EIA may be more reliable.