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Our tryst with Nucleic Acid Testing
Dolly Daniel, Dept of Transfusion Medicine, CMC, Vellore
CMC, Vellore
• A Large mission hospital• > 100 years old• Over 2200 IP beds• Over 6000 OP a day• About 75000 units of
blood / components- annual usage
• Strong component of education / service and research
BB- Id Testing
• Only Hepatitis B testing
• 1988 – HIV
• 1997 – HCV
• All testing initiated before testing became mandatory for licensing
Why NAT at CMC???
• Donor spread
• Seropositivity
• Anecdotal incidents of seroconversion
• The American Red Cross accepts blood donations only from volunteer donors.
•
• Among Red Cross donors in a given year, 19 percent donate occasionally, 31 percent are first-time donors, and 50 percent are regular, loyal donors.
Detection of HIV-1 and HCV Infections among Antibody-Negative Blood Donors by Nucleic Acid–
Amplification Testing -NEJM 2004
37,164,054 units screened Negative on serology
12 positive for HIV-1 RNA (1 in 3.1 million) (2 of which were detected by HIV-1 p24 antigen)
170 positive for HCV RNA ( 1 in 230,000)
The respective rates of positive HCV and HIV-1 nucleic acid–amplification tests were 3.3 and 4.1 times as high among first-time donors as among donors who gave blood repeatedly
Follow-up studies of 67 HCV RNA–positive donors demonstrated that seroconversion occurred a median of 35 days after the index donation
Three cases of long-term immunologically silent HCV infection were documented
Donor Profile
• Almost 70% are replacement donors
• In the West – 100% Voluntary
• Repeat donors? ??
• Process of deferral / self deferral / temporary / permanent and attitudes - very different
Linear Trend line
Linear Trend line
Issues
• Patient Safety
• (Staff requesting better ID screens)
• Quality of blood products
• One product being issued to even 5 babies
.Eskimo: "If
I did not know about God and sin, would I go to hell?"
Priest: "No, not if you did not know."
Eskimo: "Then why did you tell me?"” Annie Dillard
The Indian Experience – IJMR Feb 2008
India and NAT
• Total no of samples: 12224
• Replacement donors : 8999
• Voluntary donors : 3225
• Seropositivity - 0.26% – HIV,
0.33% HCV, 1.12% HBV
Seronegative but NAT positive
• Yield - 8 / 12224
• Overall positivity – 1/1528 donations
• HIV - 1/ 12224
• HCV / HIV 1 co infection- 1/12224
• HBV – 6/12224
NAT testing would prevent
• 3272 infectious transfusions
• 818 HIV infected units
• 409 HCV infected units & 2454 HBV infected units from being transfused.
• If components are being processed – then double or triple these numbers
Translation to the CMC scenario
• Our donor distribution is very similar
• We have about 27000 donors bled each year X 2 / 3 components
• Approx 1/1500 transfusions infected
• Therefore about 35 of our patients are being infected annually by TTIs.
• (calculation of 2 components per donation)
CMC Stats -2007-2008
IJMR seropos
CMC
seropos
IJMR
(NAT yield)
CMC Projected
HIV 32 (0.26%)
70 (0.17%) 2 NAT pos /32 seropos
12 (4x3)
HBV 137 (1.12%)
488(2.19%) 6 NAT pos /137 seropos
54 (18x3)
HCV 40 (0.33%)
214(0.96%) 1 NAT pos /40 seropos
15 (5x3)
Institution
• 3 years ……..
• Justified
• Negotiated
• Presentations to clinicians
The process
• Challenges
• Infrastructure and space requirements
• Cost impact
Assessments
• Projected numbers of possible yields
• Health technology assessment
• Permitted on a trial basis
• "The trouble with jogging is that by the time you realize you're not in shape for it, it's too far to walk back." Franklin Jones
The interim we waited…..
• No substitute for repeat voluntary donors
• No substitute for the practice of appropriate and rational use of blood
The Numbers
• Total Donors Screened – 26500
• Sero positives – 594
• Sero Negative - 25906
Seropositives
• HIV – 51 ( 0.18%)• HBV – 364 ( 1.30%)• HCV –179 ( 0.67%)
• Seropositive NAT Negative - 252• HIV – 37• HCV – 166• HBV - 49
• Total seronegative units NAT positive – 68
• Positive on repeat testing and discriminatory assays - 28 (0.105%) 1 per 950 donors approx)
Spread of positives
HBV 22
HCV 3
HBV & HCV 2
HIV 1
One time positives and their significance?
• ? False positives
• ? Low viral loads – Poissonian distribution
• Follow up recommended ?
Is it worth continuing?
• Cost per prevented infection
• At the cost of what?
• He who sleeps on the floor will not fall off the bed. Robert Gronock.
• .
In the context of transfusion services
• Has to be driven in the context of each individual institution
• Accessibility missing …… NAT available
• Basics of safe donor recruitment and appropriate use of blood and components
To conclude
• NAT seems to have worked for us…
• The confirmation of NAT yields is worth following up
• Working up samples which are one time NAT reactive – a must
Above all
• Each institution needs to thrash out the issue for itself
• Imperative that simple and safety measures like repeat voluntary donor recruitment and rational use of blood be focused upon alongside