Blood test predicts recovery time

A blood sample collected before a hip replacement operation can be used to predict how many weeks a patient will take to recover afterwards.

More than 100 million surgical procedures are carried out in the US and Europe each year. Providing patients with guidance regarding their likely recovery period is tricky because every patient is different. This also means that anticipating costs and potential side effects of surgeries is impossible.

Now a study by US scientists is set to change that. Stanford scientist Gary Nolan and his colleagues, writing in Science Translational Medicine, followed up 32 hip-replacement patients over a 6-week period post-op.

Blood samples were collected immediately before and after surgery, and then every three days afterwards. The patients' degree of fatigue, pain and abilty to function were also documented.

The scientists used a technique called mass cytometry to count the numbers of immune cells present in the blood samples and also to measure the levels of different signals being produced by those cells.

By relating these measurements with patient outcomes, the team were able to pinpoint specific combinations of cell counts and chemical characteristics that are present by 24 hours post-op and which predict the course of an individual's recovery over the following weeks.

"One cell type we studied increases ten fold within 24 hours," says co-author Brice Gaudilliere. "And its activity within the first 24 hours predicts the rapidity of recovery from the surgery."

Apart from informing patients of the likely course of their recovery, the findings also raise the tantalising possibility that it might be possible to use drugs to manipulate the activity of the immune system to minimise recovery times.