Calculated platelet dose: Is it useful in clinical practice?

The corrected count increment (CCI) can standardize assessment of platelet transfusions by correcting for patient's body surface area (BSA) and platelet dose (PD). By using a fixed CCI and a desired post-transfusion platelet count, CCI formula can be used to calculate PD. Our transfusion service has used the following formula since May 1990, to determine the number of platelet units to transfuse in non-bleeding patients: Platelet count^desired-Platelet^pre/7000× BSA(m²/1.7 (1) where, 7,000 is expected platelet count increment per unit transfused, and 1.7 is BSA in square meters in a normal adult. To evaluate its usefulness, a retrospective review was performed of all 2,202 platelet transfusions at our level-one trauma center, between 1/1/98 and 12/31/00. Eighty-three transfusions in 69 adult patients, in which a calculated PD was determined prior to transfusion, were evaluated for platelet increments at 1, 1-18, or 18-24 hours post-transfusion. Transfusions that used the calculated PD (n = 49) were compared with those that were based on clinical judgment alone (n = 34). These two groups were comparable in their pre-transfusion platelet counts, ABO compatibility, and unit storage duration. The mean calculated PD transfused in the first group was 6 U ± 1 standard deviation, which was not different from the second group (P = 0.2). There was no difference in the platelet count increments at 1, 1-18, or 18-24 hours post-transfusion. This study suggests that using a PD based on the CCI formula does not reduce platelet usage when the routine PD is six or less platelet concentrates.