Effect of platelet storage time on platelet measurements: a systematic review and meta-analyses.

BACKGROUND: The storage time of platelet products negatively affects bacterial safety and platelet function. However, low maximum storage time increases outdating of valuable products. Thus, to quantify the effect of platelet storage time on platelet measurements after platelet transfusion, a systematic review and meta-analyses were performed.

METHODS: Reports and meeting abstracts of randomized trials and observational studies, performed in humans, reporting platelet measurements after transfusion of platelet products of different storage times, were selected until February 2016. Meta-analyses were performed for four different storage time contrasts, each answering a different question. Random-effects models were used to account for substantial heterogeneity and the weighted mean differences calculated.

RESULTS: Our search strategy yielded 4234 studies of which 46 papers satisfied the inclusion criteria. As judged by the 1-h corrected count increment, transfusions of fresher platelets compared to stored platelets showed better increment. The weighed mean difference varied from 2·11 (95%CI: 1·51-2·71) to 2·68 (95%CI: 1·92-3·45). For the 24-h corrected count increment, the weighted mean difference varied from 1·36 (95%CI: 0·12-2·60) to 1·68 (95%CI: 1·07-2·28) depending on the contrast. Recovery and survival of old platelets as percentage of fresh platelets were 81% and 73% for the original definition contrast. For the extended storage contrast, recovery and survival were 75% and 68%.

CONCLUSIONS: Fresh platelets were superior to old platelets for all platelet measurements and for all storage time contrasts meta-analysed.