ABSTRACT
Background: In order to scale up access to HIV counselling and testing in Nigeria; an HIV diagnostic algorithm based on rapid testing was adopted. However; there was the need to further evaluate the testing strategy in order to better assess its performance; because of the potential for false positivity.Objectives: The objective of this study was to compare positive HIV test results obtained from the approved rapid testing algorithm with results from western blot tests performed on samples from the same patient.Methodology: A retrospective review was conducted of HIV screening and confirmatory results for patients seen between 2007 and 2008. Rapid test and western blot results were extracted and compared for concordance. Discordant results were further reviewed using a combination of HIV-1 RNA viral load and CD4+ cell count test results and clinical presentation from medical records. Results: Analysis of 2228 western blot results showed that 98.3% (n = 2191) were positive for HIV-1; 0.4% (n = 8) were positive for HIV-2 and 0.3% (n = 7) were dual infections (positive for both HIV-1 and HIV-2); 0.6% (n = 13) were indeterminate and 0.4% (n = 9) were negative. Further investigation of the 13 indeterminate results showed nine to be HIV-1 positive and four to be HIV-negative; for a total of 13 negative results. The positive predictive value of the HIV counselling and testing algorithm was 99.4%.Conclusion: Using the rapid testing algorithm alone; false positives were detected. Therefore; effective measures such as training and retraining of staff should be prioritised in order to minimise false-positive diagnoses and the associated potential for long-term psychological and financial impact on the patients
Subject(s)
Algorithms , HIV Infections/diagnosis , HIV SeropositivityABSTRACT
Issues: Quality-management systems (QMS) are uncommon in clinical laboratories in Nigeria; and until recently; none of the nation's 5 349 clinical laboratories have been able to attain the certifications necessary to begin the process of attaining international accreditation. Nigeria's Human Virology Laboratory (HVL); however; began implementation of a QMS in 2006; and in 2008 it was determined that the laboratory conformed to the requirements of ISO 9001:2000 (now 2008); making it the first diagnostic laboratory to be certified in Nigeria. The HVL has now applied for the World Health Organization (WHO) accreditation preparedness scheme. The experience of the QMS implementation process and the lessons learned there in are shared here. Description: In 2005; two personnel from the HVL spent time studying quality systems in a certified clinical laboratory in Dakar; Senegal. Following this peer-to-peer technical assistance; several training sessions were undertaken by HVL staff; a baseline assessment was conducted; and processes were established. The HVL has monitored its quality indicators and conducted internal and external audits; these analyses (from 2007 to 2009) are presented herein. Lessons learned: Although there was improvement in the pre-analytical and analytical indicators analysed and although data-entry errors decreased in the post-analytical process; the delay in returning laboratory test results increased significantly. There were several factors identified as causes for this delay and all of these have now been addressed except for an identified need for automation of some high-volume assays (currently being negotiated). Internal and external audits showed a trend of increasing non-conformities which could be the result of personnel simply becoming lax over time. Application for laboratory accreditation; however; could provide the renewed vigour needed to correct these non conformities. Recommendation: This experience shows that sustainability of the QMS at present is a cause for concern. However; the tiered system of accreditation being developed by WHO-Afro may act as a driving force to preserve the spirit of continual improvement