Platelet Process Improvement Project - Comparison of platelets stored for 2-5 days versus platelets stored for 6-7 days in preventing and treating haemorrhage in thrombocytopenic patients – a randomised controlled trial

Are platelets stored for 6-7 days as clinically effective as 2-5 day old platelets?

What was this study about?

Platelets are blood cells that are given to patients to prevent or stop bleeding. Before use, platelets have to be stored at room temperature because they stop working if they are put in a fridge. Storing platelets at room temperature before transfusion increases the risk of any bacteria present growing. To reduce this risk, platelets were only normally stored for up to 5 days before transfusion.

At the time of the PPIP trial, NHS Blood and Transplant were planning to introduce a system for screening all platelet donations for bacteria in order to improve the safety of platelet transfusions. Platelets that have been tested for bacteria may be stored for longer, up to 7 days. Extending the shelf life of platelets to 7 days would help maintain sufficient stock levels of platelets as well as making them safer because they have been tested for bacteria. This study aimed to show that platelets that had been stored for longer work just as well at preventing and stopping bleeding as platelets stored for up to 5 days.

Patients who have had a transfusion of platelets stored for up to 5 days and a transfusion of platelets stored for 6-7 days will be assessed after each transfusion to compare any differences in bleeding and compare any increase in the patient's own blood platelet count.

What difference did this study make?

The usual time a bag of platelets could be stored used to be 5 days. This is because they have to be stored at room temperature (22 degrees C), and this promotes growth of any bacteria that may be in the bag.  In order to ensure that platelets do not transmit infections, NHSBT wanted to test each bag for bacteria. However, doing that takes time, and would have meant that each bag of platelets was only available to be transfused for one or two days, leading to a lot of wastage.  The PPIP trial showed that extended shelf-life (6-7 day old) platelets are safe and do not result in decreased effectiveness or an immediate  increase in platelet  requirements compared to 2-5 day old platelets. The trial provided the evidence to allow bacterial screened platelets to be stored for longer, thus reducing infections by destroying any bags of platelets found to be infected, and reducing wastage of this expensive resource. The results are also helping other countries such as Canada and Australia to assess whether to introduce bacterial screening for their platelets.

Type of study

Randomised trial

Contact details


Who funded the study?

NHS Blood and Transplant

When did it take place?

Recruitment opened 19/09/2007 and closed 31/03/2012.

Where did it take place?

This trial took place in hospitals in Bristol and Manchester

Who was included?

Adults with blood cancer with a low platelet count (thrombocytopenia) due to bone marrow failure who require platelet transfusion. Patients must have been able to give informed consent to be included in the study. The accrual target was 120 patients with evaluable primary outcome data