External Quality Assurance Scheme in a National Reference Laboratory for HIV Testing in South India

Abstract

Background: The Department of Experimental Medicine functions as the National Reference Laboratory (NRL) for HIV testing covering 11 Medical Colleges (State Reference Laboratories SRL) & 723 subcenters i.e. Integrated Coun-seling & Testing Centres and Blood Banks. The External Quality Assurance Scheme (EQAS) in NRL implements Quality Control (QC) Testing, Proficiency panel testing and training programs. Materials & Method: 9419 samples (4393 HIV negative/5026 HIV positive) were tested for QC. All the samples were tested using HIV rapid test (Com-bAids) and HIV positives alone were tested using Tridot and EIA Comb. The QC samples consisted of 20% negative and all positives. All the 723 subcenters were provided with 5 coded plasma samples (3 reactive & 2 negative) for pro-ficiency testing using rapid tests. The aliquot panel (500 μl) were provided twice a year for testing to monitor the labo-ratory performance. Results: Out of 9419 samples tested for QC, 9371 (99.49%) reported correct results and 48 (0.50%) discordant results. Out of 48 samples 26 (0.27%) were false positives and 22 (0.23%) false negative. Mislabeling, sam-ple contamination, leaking vials, transcriptional errors, tests that were not performed correctly were identified. For pro-ficiency testing 91.8% reported test results. 645 (97.13%) reported correct results & 19 (2.86%) incorrect results. Out of 19 samples 7 (1.05%) were false positive & 12 (1.80%) were false negative. Hands on training were provided and the 19 discordant centers reported correct results on retesting. Conclusion: Significant progress in establishing a well coor-dinated HIV Laboratory network of NRL and SRLs had been developed. However the HIV testing and Quality Assur-ance needs to be strengthened towards certification.