1. CONFIRMATION OF HIV RESULTS THROUGH RETESTING POSITIVE AND NEGATIVE SAMPLES IN A RESOURCE LIMITED SETTING
A CASE STUDY BY NAKASERO BLOOD BANK (NBB) QC LABORATORY/CDC/UVRI(Entebbe) Author; Susan Acana Elaborot; DR kyeyune Dorothy
Uganda Blood Transfusion Service, Nakasero Blood Bank

2. Introduction
The mission of a blood transfusion service is to provide safe blood for therapy.
BT is one of the most effective means of transmitting TTI’s

3. CONT’D
The screening methods should be highly sensitive, specific, low cost, easy to perform, and of high predictive value
NBB blood is tested according to National a logarithm developed by UBTS, consists of first line testing on Architect system and second line testing on ELISA system as second line assay
quality systems should be in place to ensure accurate results, prevent false discards & deferrals.

4. CONT’D
Misunderstanding of the importance of QA by management can make it appear hard to apply in routine work or expensive.
In UBTS the difficulty to maintain quality can mainly be associated with;
limited resources, human errors, or negligence rather than technical problem.

5. Problem statement
The two screening methods have show discordance with mainly HIV and HCV test Results, making it critical control point for QA Dept

6. methods
A case study was done from July 2012 to June 2013 on 1718 samples to confirm the results from the first line and second line methods
Positive & negative samples were randomly picked after testing by NBB and sent for retesting on HIV to UVRI/CDC

7. methods
Samples were classified as A (negatives) on first line, B (positives)both first and second line and C (discordant)
The class A and B samples were retested on 2 ELISA methods, while class C samples were done on PCR by CDC

8. Results Total conc. 96.04 3.95 Average 96.70 3.29 Positives 70.18
total concordance between UBTS and UVRI was at 96.04% and discordance 3.95 %.
Average conc %,disc. 3.29%
Positive tests(class B) Concordance was 70.18%,
Negative tests(Class A)was 99.51%.
Discordance between Architect and ELISA was at 24.45%
Total of 6 samples had unresolved results(0.34%)
CONCORDANCE
(%)
DISCORDANCE(%)
Total conc.
96.04
3.95
Average
96.70
3.29
Positives
70.18
29.82
Negatives
99.51
0.49
Between First line &Second line
75.55
24.45

9. NBB vs. UVRI results

10. Results First line architect 29.45 Second line ELISA 29.89 1.64 method
False positives with Architect method (class C) (29.45)%
False pos on ELISA method was (29.89)%
False Negatives on Architect method was (0)%
False Negatives on ELISA (1.64)%.
method
False positives (%)
False negatives
(%)
First line architect
29.45
Second line ELISA
29.89
1.64

11. Conclusion
There is evidence that NBB generally issues HIV safe blood for the community and the Architect method used as first line is effective for its purpose
The margin of discordance between Architect method and ELISA method is significant that third test(tie breaker)could be necessary to resolve the positives

12. Recommendation
Confirmatory kits for HIV may need to be introduced and tie breaker methods e.g. PCR or NAT can be useful as back up to the second line.

13. Recommendation con’t
This is mainly for results to be used as indicators for;
donor selection criteria.
diagnosis if NBB is to continue releasing results to donors,
To reduce on discards, and false deferrals

14. Acknowledgements
UBTS management
UVRI staff
NBB staff

15. Asante