IDT vs. Pooling

Effective healthcare is a constant balancing act between affordability and quality of care. Blood centers must tackle this conflict when weighing the sensitivity of individual donor testing (IDT) against the efficiency of pooled testing.

Pooled Testing

In laboratories challenged with limited operator resources, budget constraints, and demands for quick turnaround, using pooled testing to decrease workload is appealing. Standard semi-automated systems, like the PROCLEIX® WNV Assay run on the PROCLEIX® eSAS System, can test up to 94 samples in 5 hours. This could equate to 1,500 donor units, at pools of 1:16, dispositioned during this period with a mere thirty minutes extra for pooling time. Although this seems very attractive, the efficiency of this method may be affected if reactive pools occur and retesting is required.

Individual Donor Testing

The strength of Individual Donor Testing (IDT) lies in the increased sensitivity of the results. Even though pooled is highly sensitive, it may still miss an infected sample because the target virus is diluted 16-fold. This can occur due to low virus counts, and during the "window period" of infection, where the donor is positive but may have a negative pooled screening test. This is especially evident for West Nile Virus (WNV), which does not replicate at the same rate as a virus like HIV, during the early stages of infection. Several cases have been reported in which transmission of WNV occurred in patients tested under pooled conditions. Upon retesting, these same samples were all reactive in IDT. A retrospective analysis found about 25% of the infected units that have been intercepted by IDT would not have been caught with pooled testing1.

A Solution

The trade-off of increased workload with IDT can be mitigated through automation. The PROCLEIX® TIGRIS® System is a fully automated platform that can produce 1,000 results in approximately 14 hours, irrespective of pooled or IDT samples2. Being fully automated, the PROCLEIX TIGRIS System also requires minimum hands on time, offering greater walkaway capability. The throughput and walkaway capability of the PROCLEIX TIGRIS System allows the laboratory to decide on a testing algorithm that most optimally suits their workflow needs.

 

References

  1. Food and Drug Administration, American Red Cross, Blood Systems Laboratories. 2006. Protective Role of Natural Antibodies in WNV Infection: In Vitro Infectivity of WNV ID NAT Reactive Plasmas Containing Specific Antibodies (IgM and/or IgG). Vox Sanguinis. Vol. 3, Supplement 3: 72
  2. PROCLEIX TIGRIS System Operator's Manual