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XVIII INTERNATIONAL AIDS CONFERENCE JULY 18 – 23 2010, VIENNA AUSTRIA

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

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XVIII INTERNATIONAL AIDS CONFERENCE JULY 18 – 23 2010, VIENNA AUSTRIA

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  1. 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

  2. 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

  3. 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

  4. DNA-PCR Testing Protocol • 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

  5. Quality Assurance • Internal Quality Control • Review results before reporting • Inter-laboratory QC • Proficiency Testing & re-testing (CDC-Atlanta) • Staff competency

  6. 18,000 DNA-PCR tests by end of 2009

  7. 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

  8. Methods • DNA-PCR test results done in 2009 analyzed. • Assessment of the second test result for all specimens with initial; - positive result - indeterminate result - invalid result • Electronic data of DNA PCR results were analyzed using STATA™ version 8.

  9. Discordance: Initial vs. 2nd test

  10. Frequency of discordance: 2nd test

  11. 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

  12. 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.

  13. 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

  14. DNA-PCR operation

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