| BackgroundLaboratory assays that can. accurately measure HIV incidence in cross-sectional population are critically needed to monitor the HIV epidemic, detect high-risk population and measure the effectiveness of prevention strategy. Limiting antigen avidity enzyme immunoassay (LAg-avidity EIA) which is a newly-developed Serological Testing Algorithm for Recent HIV Seroconvertion (STARHS), has improved a lot in accuracy than previously used BED Capture enzyme immunoassay(BED CEIA). LAg has a lower false recent ratio in long-term HIV-infected individuals and were more tolerant to disease progress and Antiretroviral Treatment(ART), thus could obtain more accurate HIV incidence.Objective1. To obtain HIV incidence of China sentinel population using LAg and compare the results with those of BED, providing performance data in applying and find out potential problems for improvement.2. To access the prevalence of HIV infection and the associated factors among MSM in China sentinels of2011according to the questionnaire information, providing basis for effective prevention measures of implementation. Objects and Methods1.1442samples of HIV high risk population, which were MSM、DUS、FSW and STD population,were collected from HIV sentinels of14provinces,2011. These samples were tested by LAg, corresponding BED results were provided by every province. Consistency and HIV incidences of two methods were compared. HIVincidence was calculated using the WHO recommended formula for laboratory-based method. HIV incidence obtained by LAg was adjusted with international published parameters; HIV incidence of BED was adjusted with parameters of our country.2. HIV incidences were calculated using different parameters, which were obtained in previous studys. The parameters include international and our country parameters obtained at different cutoff values (unpublished).3.19613questionnaires of MSM sentinal population were uploaded from "National AIDS Comprehensive Prevention and Control Information System". Demographic information, Basic knowledge on AIDS, relevant ethological factors and serological results of each province were described. Analyse the influence factors of HIV recent detection results between LAg and BED.HIV prevalence and relevant ethological factors were analyzed by Logistic regression model.Results1.LAg detected312samples as recent infection of al1442ones, the recent infection ratio was21.6%;404samples were classified as recent by BED, the BED recent infection ratio was28.0%, which was higher than LAg. The consisitnecy rate was89.9%, Kappa value was0.73. There were statistical differences among MSM and DUS population who had higher HIV prevalence between the HIV recent ratios of two methods. In these populations, LAg detected less samples as recent infected than BED. While no differences were found between the HIV recent results of two methods among FSW and STD population. This may be attributed to the lower prevalence of HIV among those populations, which led to few samples for detection. 2. HIV incidence estimates by LAg and BED were similar. HIV incidences obtained by LAg for MSM, DUS, FSW and STD population were3.94%(95%CI:3.32-4.56%),0.07%(95%CI:-0.01-0.15%),0.06%(95%CI:0.02-0.09%) and0.17%(95%CI:0.10-0.24%), respectively.BED incidences were3.49%(95%CI:2.99-3.99%),0.04%(95%CI:-0.01-0.15%),0.04%(95%CI:0.01-0.07%) and0.12%(95%CI:0.07-0.18%).respectively.3. There was no statistical difference between HIV incidences obtained by LAg adjusted by international paraameters at different cutoff values. LAg cutoff values increased from1.0to1.75, MSM population incidences were4.18%(95%CI:3.45-4.91%),3.94%(95%CI:3.32-4.56%) and3.76%(95%CI:3.22-4.31%), respectively. DUS HIV incidences were0.02%(95%CI:-0.04-0.08%),0.07%(95%CI:-0.01-0.15%) and0.07%(95%CI:-0.01-0.14%).respectively. FSW HIV incidences were0.03%(95%CI:0-0.07%),0.06%(95%CI:0.02-0.09%) and0.05%(95%CI:0.02-0.09%),respectively.STD HIV incidences remained0.17%. HIV incidence estimate by LAg at cutoff value of1.0and1.5using China population parameter for MSM was2.97%(95%CI:2.54-3.41%),2.92%(95%CI:2.54-3.29%) DUS,FSW and STD population HIV incidences were0.02%(95%CI:-0.02-0.07%)/0.03%(95%CI:-0.03-0.09%),0.02%(95%CI:0-0.05%)/0.04%(95%CI:0.01-0.07%) and0.12%(95%CI:0.06-0.18%)/0.13%(95%CI:0.08-0.18%),respectively. MSM LAg incidences using China paramters at cutoff values of1.0and1.5were lower than those at the same cutoff values using international parameter. There was no statistical difference between LAg incidence estimates at different cutoff values using China population parameters and international parameters at DUS,FSW and STD population.4.5.01%of MSM sentinel individuals were HIV-positive, the average age were29.3years old, of which52.5%were between21to30,62.1%were unmarried. The han nationality accounts for95.8%, high school education and above accounted for76.9%, AIDS knowledge awareness rate was91.3%.84.1%of the individuals had sex with men in the latest six months.8.0%and31.3%of the investigaters had homesexual and heterosexual commercial sex in the nearly six months, respectively. Syphilis infection rate and HCV positive rate were8.1%and0.8%, respectively. There were differences between the distributions of the demographic characteristics and behavior factors in different provinces.5.217samples were classified as recent infection by LAg in13districts, the average age were30.2years old.277were detected as recent infection by BED, the average age were30.3years old. Demographic characteristics, behavior factors, Syphilis or HCV infection have no influences on LAg and BED result detection. More than50.0%were between21and30,61.0%were unmarried. Local residents account to70.0%. The han nationality accounts for more than90.0%. In the latest six months, homesexual rates, commercial homesexual rates and heterosexualrates of HIV rencent infection by LAg and BED were87.4%/89.4%,7.6%/6.9%and27.8%/29.0%, respectively. Syphilis infection rate were20.9%and19.4%. HCV positive rate were1.4%.6. Districts,26years of age or older, nonlocal residents, junior education level, homosexual nearly six months, unprotected sex and syphilis infection were risk factors related with HIV infection; Living time is a protection factor with HIV infection. HIV infection rate is lower with longer living period. Districts, nonlocal residents, homosexual nearly six months, unprotected sex and syphilis infection were risk factors related to BED determined new HIV infections. Districts, nonlocal residents, junior education level, homosexual nearly six months, unprotected sex and syphilis infection were risk factors related with LAg determined new HIV infections.Conclusions1. There was difference between the judgement results in crosssectional samples of the LAg and BED methods. The recent HIV infection samples of LAg than BED, which maybe related to the lower false recent ratio.2. HIV incidences obtained by LAg using international parameters of sentinal population were similar with HIV incidences obtained by BED using China parameters. 3. There was no statistical difference between LAg incidence estimates adjusted by different parameters. Apart from HIV incidences of MSM population obtained by LAg at the cutoff values of1.0and1.5, there was no statistical difference between HIV incidences obtained by LAg at differenct cutoff values using China parameters and international parameters. The window period and FRR of China population are still needed.4. There was high HIV infection rate in MSM population, High-risk behaviors were widespread, syphilis infection rate remained at a high level in some areas of China, further intervention still need among MSM population. Demographic characteristics, behavior factors, Syphilis or HCV infection have no influences on LAg and BED result detection. There were differences between demographic characteristics between HIV and HIV recent infection. There was also difference in demographic characteristic between HIV recent infection determined by LAg and BED. |
PDF Full Text Request