A world-first blood test that can objectively identify chronic pain has been developed by a team of Australian researchers. The test can reportedly identify color changes in immune cells affected by chronic pain and hopefully give doctors a new way to diagnose the severity of pain in patients unable to adequately communicate it.

"This gives us a brand new window into patients' pain because we have created a new tool that not only allows for greater certainty of diagnosis but also can guide better drug treatment options," explains lead on the new research, neuroscientist Mark Hutchinson, who is Director of the Australian Research Council Centre of Excellence for Nanoscale BioPhotonics at the University of Adelaide.

The research team found that there are identifiable molecular changes in immune cells when a person is suffering from chronic pain. Using hyperspectral imaging analysis these pain biomarkers can be instantly identified, meaning a clinician could determine a patient's pain tolerance or sensitivity and immediately adjust the dosage of a painkilling medication.

"We are literally quantifying the color of pain," says Hutchinson. "We've now discovered that we can use the natural color of biology to predict the severity of pain. What we've found is that persistent chronic pain has a different natural color in immune cells than in a situation where there isn't persistent pain."

As well as offering a new biomarker for the presence of pain, Hutchinson's research suggests that these immune cells actually play a significant role in modulating the sensation of chronic pain. This means that instead of concentrating on developing pain-killing drugs that simply target the nervous system, new drugs may be investigated that suppress this immune pain response.

"We now know there is a peripheral cell signal so we could start designing new types of drugs for new types of cellular therapies that target the peripheral immune system to tackle central nervous system pain," says Hutchinson.

The test, called "painHS", could potentially be ready to roll out into broad clinical use within 18 months, but the broader implications of this kind of objective blood test for pain is where things get really interesting. Hutchinson hopes this test could assist in diagnosing pain in subjects that cannot communicate their discomfort, from babies to older sufferers of dementia. The test may also be applicable to animals, which Hutchinson suggests could revolutionize the entire field of veterinary treatment.

"Animals can't tell us if they're in pain but here we have a Dr Dolittle type test that enables us to 'talk' to the animals so we can find out if they are experiencing pain and then we can help them," says Hutchinson.

The new test was revealed at the Faculty of Pain Medicine (FPM) conference in Sydney over the weekend.