Platelet transfusion in adults: An update

Many patients worldwide receive platelet components (PCs) through the transfusion of diverse types of blood components. PC transfusions are essential for the treatment of central thrombocytopenia of diverse causes, and such treatment is beneficial in patients at risk of severe bleeding. PC transfusions account for almost 10% of all the blood components supplied by blood services, but they are associated with about 3.25 times as many severe reactions (attributable to transfusion) than red blood cell transfusions after stringent in-process leukoreduction to less than 10⁶ residual cells per blood component. PCs are not homogeneous, due to the considerable differences between donors. Furthermore, the modes of PC collection and preparation, the safety precautions taken to limit either the most common (allergic-type reactions and febrile non-hemolytic reactions) or the most severe (bacterial contamination, pulmonary lesions) adverse reactions, and storage and conservation methods can all result in so-called PC "storage lesions". Some storage lesions affect PC quality, with implications for patient outcome. Good transfusion practices should result in higher levels of platelet recovery and efficacy, and lower complication rates. These practices include a matching of tissue ABH antigens whenever possible, and of platelet HLA (and, to a lesser extent, HPA) antigens in immunization situations. This review provides an overview of all the available information relating to platelet transfusion, from donor and donation to bedside transfusion, and considers the impact of the measures applied to increase transfusion efficacy while improving safety and preventing transfusion inefficacy and refractoriness. It also considers alternatives to platelet component (PC) transfusion.

Predicting donor-related factors for high platelet yield donations by classification and regression tree analysis

INTRODUCTION

Collecting high-dose (HD) or double-dose (DD) apheresis platelets units from a single collection offers significant benefit by improving inventory logistics and minimizing the cost per unit produced. Platelet collection yield by apheresis is primarily influenced by donor factors, but the cell separator used also affects the collection yield.

OBJECTIVES

To predict the cutoff in donor factors resulting in HD and DD platelet collections between Trima/Spectra Optia and MCS+ apheresis equipment using Classification and Regression Trees (CART) analysis.

METHODS

High platelet yield collections (target ≥ 4.5 × 10¹¹ platelets) using MCS+, Trima Accel and Spectra Optia were included. Endpoints were ≥ 6 × 10¹¹ platelets for DD and ≥ 4.5 to < 6 × 10¹¹ for HD collections. The CART, a tree building technique, was used to predict the donor factors resulting in high-yield platelet collections in Trima/Spectra Optia and MCS+ equipment by R programming.

RESULTS

Out of 1,102 donations, the DDs represented 60% and the HDs, 31%. The Trima/Spectra Optia predicted higher success rates when the donor platelet count was set at ≥ 205 × 103/µl and ≥ 237 × 103/µl for HD and DD collections. The MCS+ predicted better success when the donor platelet count was ≥ 286 × 103/µl for HD and ≥ 384 × 103/µl for DD collections. Increased donor weight helped counter the effects of lower donor platelet counts only for HD collections in both the equipment.

CONCLUSIONS

The donor platelet count and weight formed the strongest criteria for predicting high platelet yield donations. Success rates for collecting DD and HD products were higher in the Trima/Spectra Optia, as they require lower donor platelet count and body weight than the MCS+.

Meta-analysis of the studies of bleeding complications of platelets pathogen-reduced with the Intercept system

BACKGROUND

The eligibility criteria of a previously reported meta-analysis (Transfusion 2011;51:1058-1071) of randomized controlled trials (RCTs) of pathogen reduction of platelets in patients with hypoproliferative thrombocytopenia were modified to examine the impact on the findings of: (1) inclusion of a (previously excluded) RCT; (2) restriction of eligibility to RCTs of the Intercept (amotosalen-HCl/ultraviolet-A-light) system; and (3) differences in the methods used to assess bleeding complications.

MATERIALS AND METHODS

Five RCTs comparing the risk of all, clinically significant (grades 2 through 4) and/or severe (grades 3 and 4) bleeding complications between recipients of platelets treated with Intercept vs. standard unmanipulated platelets were included. Odds ratios (ORs) of bleeding complications of similar severity recorded during similar periods of observation were calculated across all studies and across homogeneous subsets of studies by random-effects methods.

RESULTS

Treatment with Intercept increased all bleeding complications when four RCTs meeting the eligibility criteria of the previous meta-analysis were integrated, but not across all the five currently available studies [summary OR=1·24; 95% confidence interval (CI), 0·79-1·93]. Clinically significant bleeding complications increased when the results of the SPRINT RCT were based on the expanded safety analysis (summary OR=1·52; 95% CI, 1·09-2·12)--but not the initial report (summary OR=1·30; 95% CI, 0·54-3·14)--of that study.

CONCLUSIONS

Treatment with Intercept may increase the risk of all and clinically significant (albeit not severe) bleeding complications in RCTs maintaining a platelet count of ≥10×10(9) or ≥20×10(9)/l through increased platelet transfusions.

Pathogen Reduction Technology Treatment of Platelets, Plasma and Whole Blood Using Riboflavin and UV Light

Bacterial contamination and emerging infections combined with increased international travel pose a great risk to the safety of the blood supply. Tests to detect the presence of infection in a donor have a 'window period' during which infections cannot be detected but the donor may be infectious. Agents and their transmission routes need to be recognized before specific tests can be developed. Pathogen reduction of blood components represents a means to address these concerns and is a proactive approach for the prevention of transfusion-transmitted diseases. The expectation of a pathogen reduction system is that it achieves high enough levels of pathogen reduction to reduce or prevent the likelihood of disease transmission while preserving adequate cell and protein quality. In addition the system needs to be non-toxic, non-mutagenic and should be simple to use. The Mirasol® Pathogen Reduction Technology (PRT) System for Platelets and Plasma uses riboflavin (vitamin B2) plus UV light to induce damage in nucleic acid-containing agents. The system has been shown to be effective against clinically relevant pathogens and inactivates leukocytes without significantly compromising the efficacy of the product or resulting in product loss. Riboflavin is a naturally occurring vitamin with a well-known and well-characterized safety profile. The same methodology is currently under development for the treatment of whole blood, making pathogen reduction of all blood products using one system achievable. This review gives an overview of the Mirasol PRT System, summarizing the mechanism of action, toxicology profile, pathogen reduction performance and clinical efficacy of the process.

Meta-analysis of the randomized controlled trials of the hemostatic efficacy and capacity of pathogen-reduced platelets

BACKGROUND

A recent independently funded randomized controlled trial (RCT; Br J Haematol 2010;150:209-17) questioned prevailing opinion concerning the hemostatic capacity of pathogen-reduced platelets (PLTs). Meta-analysis was used to calculate the effect of pathogen reduction (PR) of PLTs on hemostatic efficacy and capacity based on all available data and to investigate possible reasons for the variation in reported findings.

STUDY DESIGN AND METHODS

RCTs allocating patients to receive routine PLT transfusions with pathogen-reduced or untreated PLTs and reporting on at least one of six hemostasis endpoints were eligible for analysis. Five RCTs of hemato-oncology patients met eligibility criteria. Endpoints determined by similar criteria in all RCTs were integrated by fixed-effects methods. Endpoints determined by different criteria were integrated by random-effects methods.

RESULTS

Studies were statistically homogeneous in all analyses. Pathogen-reduced PLTs were associated with a significant (p < 0.05) reduction in 1- and 24-hour posttransfusion corrected count increments (summary mean difference, 3260; 95% confidence interval [CI], 2450-4791; and summary mean difference, 3315; 95% CI, 2027-4603) as well as a significant increase in all and in clinically significant bleeding complications (summary odds ratio [OR], 1.58; 95% CI, 1.11-2.26; and summary OR, 1.54; 95% CI, 1.11-2.13). The frequency of severe bleeding complications did not differ.

CONCLUSION

The results of the recent RCT are not inconsistent with those of the earlier studies. Introduction of PR technologies in their current stage of development would result in an increase in mild and moderate (albeit not severe) bleeding complications, which the transfusion-medicine community must explicitly tolerate to reap the benefits from PR.