Presentation on theme: "THE EFFECTIVENESS OF A RE- TESTING PROTOCOL TO ASSURE QUALITY DNA PCR TESTING FOR EARLY INFANT DIAGNOSIS (EID) IN MALAWI XVIII INTERNATIONAL AIDS CONFERENCE."— Presentation transcript:
THE EFFECTIVENESS OF A RE- TESTING PROTOCOL TO ASSURE QUALITY DNA PCR TESTING FOR EARLY INFANT DIAGNOSIS (EID) IN MALAWI XVIII INTERNATIONAL AIDS CONFERENCE JULY 18 – 23 2010, VIENNA AUSTRIA Wainings Manda-EID Lab Coordinator R Mwenda, H Moyo, J.Bitilinyu, C Porter, M Kabue, M Eliya HUTAP
Malawi Demographic Profile 2008 Population: 13.6 Million HIV/AIDS Prevalence - Adult and adolescents: 12% HIV/AIDS – In children: 30,000 new infections annually U5MR: 110 deaths per 1,000 live births
DNA PCR Laboratory Capacity EID was implemented in Malawi in 2007 Currently 2 government labs perform PCR Infants <18 months are testing using DNA PCR on dried blood spots (DBS) A total of 18,000 infants were tested at the end of 2009. A total of 4000 HIV-infected infants were identified
DNA-PCR Testing Protocol Initial n Initial negative result – reported Initial positive result - re-tested - confirmed pos results are reported Indeterminate results are retested in duplicate Invalid- request for a fresh specimen
Purpose EID scale up resulting in higher volume Current protocol requires re-testing all positive results Re-testing: - expensive - time consuming Evaluation of retesting protocol was necessary
Methods DNA-PCR test results done in 2009 analyzed. Assessment of the second test result for all specimens with initial; - positive result - positive result - indeterminate result - invalid result Electronic data of DNA PCR results were analyzed using STATA™ version 8.
Discordance: Initial vs. 2 nd test Name of Laboratory Number of specimens with initial positive test Number of specimens with discordant 2 nd test result Proportion of discordance KCH7318311.35% QECH135815311.27% TOTAL2,08923611.31%
Conclusion 89% of initial positives were confirmed positive on re-test A majority of the discordant specimens re-tested yielded HIV negative results Re-testing is necessary
Lessons learnt High sensitivity of test assay may contribute to initial false positive results. Other factors that may lead to initial false positive results are; - human error - contamination of specimens Re-testing specimens rules out false positive results.
Recommendations Malawi should continue with the current protocol of re-testing all initial DNA-PCR HIV positive results and discordant results. More specific assays are needed. Urgently request for re-collection of DBS specimen for invalid result