Corrected count increment and percent platelet recovery as measures of posttransfusion platelet response: problems and a solution

BACKGROUND: Corrected count increment (CCI) and percent platelet recovery ( PPR) are measures of response to platelet transfusion that "correct" the co unt increment for blood volume and number of platelets transfused. their po tential for data distortion is described, and a regression analysis is sugg ested that is more informative and avoids the inherent problems associated with using ratios as outcome-measures. STUDY DESIGN AND METHODS: Data from the first platelet transfusion for 585 patients from the Trial to Reduce Alloimmunization to Platelets (TRAP) were used to model methods of analyzing posttransfusion platelet response. RESULTS: By linear regression analysis, unfiltered platelet components gave a greater posttransfusion increment on average (p = 0.001), but filtered p latelets gave a greater increment per platelet transfused (p = 0.003). In c ontrast, CCI and PPR showed no difference between filtered and unfiltered p latelets (p = 0.36 and p = 0.29, respectively) because they combined the ef fects of dose, filtration, and patient size. Slightly fewer patients are re quired for a study analyzed by regression analysis. CONCLUSION: Regression analysis of posttransfusion platelet increments shou ld be used instead of CCI or PPR to compare the efficacy of platelet compon ents. CCI and PPR should not be used to define platelet refractoriness as a study outcome, because these measures are biased in favor of platelet prep aration techniques that provide fewer platelets.