The paper is entitled, "Hold Everything! Holding policies for Protecting Plasma Supplies." The authors are Edward H. Kaplan, Yale School of Management, and Glen A. Satten, United States Centers for Disease Control and Prevention.
Picking the Better of Two HIV Tests
The authors used operations research and statistical modeling to assess holding periods to reduce the chance of a potentially infectious unit being passed on for further processing. If done correctly, subsequent plasma processing eliminates the risk of HIV transmission through heat treatment. The researchers evaluated two additional measures that would guard against the rare possibility that processing could be done incorrectly.
Considering the sometimes competing pressures of cost vs. safety, they compared two possible strategies for screening plasma donations for HIV before processing: (1) holding all of a donor's blood plasma donations for a specific time and (2) testing the same plasma using a new, expensive screening test called PCR (polymerase chain reaction).
Holding all of a person's blood plasma units for 21 days reduces the probability that an infectious donation escapes detection by 50% at a cost of 29 cents. In contrast, they found, using PCR has the same rate of effectiveness but costs $8, more than 25 times as much.
Achieving the Safest Possible Blood Plasma Supply
A multifaceted approach currently ensures the safety of blood plasma. Advances in testing technology, coupled with heat treatment which inactivates infections such as HIV, HBV, and HCV, has virtually eliminated the risk of infection with these diseases through blood plasma. Occasionally, plasma is collected that is potentially infectious, but not detected because the donor has not yet developed levels of HIV antibody (or p24 antigen) that can be identified by screening tests, the authors explain. This occurs when plasma is collected in donors who were recently infected with HIV. To eliminate the risk of transmission from these donations, blood plasma products are heat treated. There have been no cases of HIV transmission through blood plasma since heat treatment began.
To guard against the possibility of errors in plasma processing, the blood plasma industry has embarked on a comprehensive program to screen out the few potentially infectious units before processing. This program includes accepting only donations from repeat, qualified donors and implementation of the hold period. Under the type of holding policy described in the paper, all donated units are stored before being released for fractionation and the production of plasma products. If a donor tests positive for the infection in question at a subsequent donation, then all of that donor's units currently in storage are discarded. Otherwise, donated units are released for processing at the end of the holding period.
The study will be published in a forthcoming issue of the journal Mathematical Biosciences.
Operations Research
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