Preliminary validation of a new standard of efficacy for stored platelets

Platelet preparation and storage systems, unlike those for RBC, lack an objective, absolute performance criterion to determine acceptability. Recently, a criterion based on paired comparison with the radiolabeled recovery and survival of "fresh" platelets has been proposed, namely, recovery = two-thirds and survival = half of "fresh" platelets.

Eleven normal subjects donated a unit of leukoreduced apheresis platelets using a standard, approved system. They received an aliquot radiolabeled with 111In or 51Cr (random selection) 4 to 20 hours after donation and, using the other radioisotope, on Day 5 of storage. The recovery was calculated based on the injectate radioactivity. The survival was determined using the multiple-hit model. The area under the platelet survival curve was calculated using the COST program.

Reinfusion of platelets less than 20 hours after collection resulted in a recovery of 74.7 +/- 12.3 percent and a survival time of 7.5 +/- 1.1 days. Reinfusion on Day 5 resulted in a recovery of 58.2 +/- 12.0 percent and a survival time of 6.9 +/- 1.4 days, values that were 77.9 +/- 9.5 percent and 91.8 +/- 16.1 percent of the observation using "fresh" platelets, respectively. The area under the curve using Day 5 platelets was 67.8 +/- 11.5 percent of that using "fresh" platelets.

The proposed criterion for objective evaluation of platelet preparation and storage systems appears applicable to a commonly accepted approach, leukoreduced apheresis platelets stored in plasma for 5 days, and merits evaluation using other collection, treatment, and storage systems.