A one-of-its-kind blood test to measure pain in patients could open the door to precision medicine and help stem the tide of the opioid crisis, say researchers.

Until now, to assess pain - a subjective sensation - doctors had to rely on patients self-reporting or the clinical symptoms. But the novel blood test can help objectively determine how severe a patient's pain is, allowing physicians far more accuracy in treating it. "We have developed a prototype for a blood test that can objectively tell doctors if the patient is in pain, and how severe that pain is," Alexander Niculescu, Professor of Psychiatry at Indiana University, said. 

With an opioid epidemic raging, Niculescu said never has there been a more important time to administer drugs to patients responsibly. "The opioid epidemic occurred because addictive medications were overprescribed as there was no objective to measure whether someone was in pain, or how severe their pain was," Niculescu said, in a paper detailed in the journal Molecular Psychiatry. 

In addition to providing an objective measure of pain, the blood test helps physicians match the biomarkers in the patient's blood with potential treatment options. The researchers utilise a prescription database to match the pain biomarkers with profiles of drugs and natural compounds catalogued in the database.

"The biomarker is like a fingerprint, and we match it against this database and see which compound would normalise the signature," Niculescu said. 

"We have been able to match biomarkers with existing medications, or natural compounds, which would reduce or eliminate the need to use the opioids." Moreover, the team discovered biomarkers that can also help predict when someone might experience pain in the future - helping to determine if a patient is exhibiting chronic, long-term pain, which might result in future emergency room visits.