When I started my COVID-19 convalescent plasma CCP collection in early March, 2020, there were few antibody tests available. However, I anticipated that eventually we would want to include antibody results with the donor record. Antibody results were not used originally at all in the criteria for CCP acceptability for release.
There are many assays by type of antibody (total, IgG, IgA, IgM) and quantitation by titer and/or signal-cutoff ration S/CO. Any of these parameters may be used to define rules for acceptability to complete production and/or allocate to patients. Instrumentation used for titering/quantitation may be interfaced to the blood bank software.
Here is my generic approach to including these results with the donation record. In Medinfo HIIG, it is possible enter test results retrospectively and these can be used set rules for acceptability. Please consult with my detailed post on using rules against parameters.
All of this is easily implemented since all test information will be stored as parameters. From these parameters we can construct rules for:
- Low titer CCP
- High titer CCP
- Acceptability for patient allocation
Also, one can override the rules if the clinician and the transfusion medicine physician agree. For example, there is a severe shortage of group B CCP so use of low-COVID-antibody titer group B CCP could be allowed.
The key is to build whatever test methodology you use and include the manufacturer’s cutoff for low versus high titer interpretation. These results can be printed on the ISBT label as well. One can easily build multiple methodologies and acceptability criteria if different tests are used at different testing sites in your system—just as can be done for other tests (ABO/D, antibody screen, etc.) If one changes methodologies in the future, Medinfo will still use the same rules that applied for the day of production.
Here are some sample test rules:
Example 1: Total COVID antibody > 160 is high titer:
- If antibody >= 160, label as high-titer CCP and use for patient allocation.
- If antibody < 160, label as low-titer, physician must override for patient allocation
Example 2: IgG antibody with S/CO ratio > 12 is high-titer:
- If S/CO >= 12 label as high-titer CCP and use for patient allocation.
- If S/CO < 12, label as low-titer and discard.
Example 3: IgG and IgM antibodies must have S/CO > 12:
- If BOTH IgG and IgM antibody measurements have S/CO >12, use for patient allocation.
- Otherwise, discard unit.
Another option would be just to record the quantitation for each antibody type and list this on the ISBT label and permit its release regardless of the value. One could also permit low-anti-B titer group A plasma with whatever rules you set up.