Cleveland Clinic Foundation Cleveland, Ohio, United States
Background/Case Studies: The corrected count increment (CCI) is a calculated value that is utilized to help determine if a patient is refractory to platelet transfusions. The CCI is calculated by multiplying the patient’s body surface area by the reported platelet increment. This is then divided by the platelet yield of the transfused unit. Many institutions use an estimated yield of 3x1011 platelets, rather than the actual platelet yield, as this is the current minimum platelet count requirement for apheresis units in the United States. Using an estimated yield, which is frequently lower than the actual yield, may lead to an overestimation of a patient’s CCI.
Study
Design/Methods: During the period between January and March of 2024, platelet yield tags from human leukocyte antigen selected platelets were collected at a blood bank in a midwestern quaternary care center. The actual platelet yield was documented. Following administration to a patient, the pre- and post-transfusion platelet count for that patient was also documented when possible. A CCI was calculated for those patients using both the actual platelet yield and the estimated yield of 3x1011platelets.
Results/Findings: The minimum actual platelet yield was 2.9 x 1011 platelets, and the maximum was 4.4 x 1011 platelets. The mean actual yield was 3.5 x 1011 with a median of 3.4 x 1011 platelets. Of forty unique transfusion events, there were sixteen total patients who received these units. For thirteen of these, both a pre- and post-transfusion platelet count was obtained (32.5%). In 11 of those 13 cases, counts were obtained within the 10 minutes to 1 hour required window to appropriately calculate a CCI. The average calculated CCI using the actual platelet yield was 6.14 m²/µL compared to the average predicted CCI of 8.11 m²/µL using the estimated yield. There was a statistically significant difference between the actual platelet yield and the estimated yield (p< 0.00001), however, there was no statistically significant difference between the calculated CCIs when using the actual yield vs the estimated yield (p=0.75). Conclusions: There is a significant difference between the actual and predicted platelet yields, but this did not translate to a significant change in the calculated CCI. This data indicates using an estimated platelet yield of 3x1011 in CCI calculations is an appropriate practice. Blood suppliers may not always be able to provide a platelet yield on all products, making it important to know that this estimated yield is reliable for calculating accurate CCIs.
