Use of Granulocyte Transfusions in Two National Cohorts and Association between Transfusion Dose and Patient Outcomes: The Best Collaborative Study

Granulocytes for transfusion (GTX) continue to be administered, mostly to treat refractory infection 1. Single center series continue to be reported, but evidence of GTX effectiveness remains uncertain. Recent attempts at randomized trials of GTX have not been completed to target although the largest trial, RING 2, identified potentially promising results in a sub-group analysis by dose. GTX can be produced by apheresis (from ‘stimulated’ donors), aGTX, or as a component pooled from whole blood (WB) donations. Logistic difficulties arise with aGTX, including recruitment of suitable donors willing to undergo cell mobilization and collection. In England GTX are now only supplied as pooled (10 WB donations/pool, mean volume single pooled unit 207 ml, mean granulocyte yield/unit 0.9 x10 10, typical adult dose 2 pools, available 6 days per week). In France, production moved from aGTX to pooled in 2020 (20 WB donations/pool, mean volume single pooled component 428 ml, mean granulocyte yield/unit 1.8 x10 10, typical adult dose 1 pool, available 6 days per week). There have been no recent published national data on the clinical use of pooled granulocytes, or comparisons between large datasets. The aim of this study was to 1) describe the use of GTX, including pooled granulocytes, in two national cohorts of recipients; 2) estimate the effect of dose on patient mortality using statistical methods which could be applied to a larger dataset in the future. A pre-piloted data collection form (DCF) was used to collect prospective audit data on all GTX given to patients in participating hospitals in England from March 2017 -Sept 2020 in England. The PROspective Granulocyte usage and outcomEs Survey (ProGrES) was deemed a national registry/audit with no individual patient consent required for anonymized data. Information on patient characteristics and outcomes was collected at the time of the request for GTX, following completion of GTX and at 28 days and 6 months follow up. DCFs were adapted for international use, and French data were collected from Jan 2018 to Dec 2020. Descriptive analyses were performed to summarize GTX dose, patient characteristics, and outcomes. Using the English data, we investigated the association between GTX dose and mortality within 28 days of final GTX using logistic regression models with and without adjustment for possible confounders (age, infection source, use of renal therapy) and using the target trial framework. Ethical approval was obta