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 Counseling & 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 (CombAids) 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 proficiency testing using rapid tests. The aliquot panel (500 μl) were provided twice a year for testing to monitor the laboratory 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, sample contamination, leaking vials, transcriptional errors, tests that were not performed correctly were identified. For proficiency 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 coordinated HIV Laboratory network of NRL and SRLs had been developed. However the HIV testing and Quality Assurance needs to be strengthened towards certification.