Biomarkers for pain assessment are needed for more accurate pain therapy treatment in patients unable to reliably self-report their circumstances such as patients with dementia, intubated patients, and infants. The authors of a study recently published in Biomarkers in Medicine, Soluble intercellular adhesion molecule-1: a potential biomarker for pain intensity in chronic pain patients, hypothesized that pain intensity might be assessable using inflammatory molecules measurable in serum.

The observational, single center study looked at the cytokine profiles in patients with mild to severe pain (n=71) and healthy control participants (n=24). A panel of 30 pro- and anti-inflammatory cytokines were measured using multiplex immunoassay xMAP (Multi-Analyte Profiling) technology, Human CytokineMAP A & B.

Both IL-6 and sICAM-1 serum levels differentiated patients with mild pain and patients with moderate to severe pain, but only sICAM-1 showed significant correlation between self-reported intensity levels and measured serum levels in the patients.

IL-23 was compared along with IL-6 and sICAM-1 based on a logistic regression model in efforts to identify a biomarker panel to separate controls and mild pain patients with those with more severe pain but only sICAM-1 remained to differentiate the two groups.

Patients were studied in an initial screening, follow-up set, and a prospectively validated set for sICAM-1 only. Results showed a normal distribution of sICAM-1 among the control group. Therefore, the researchers defined a cut-off value one standard deviation from the mean and calculated both sensitivity and specificity. The sensitivity ranged from 0.77 to 1.0 and specificity from 0.57 to 1.0.

Not only did the study results show that sICAM-1 levels in serum correlate with the participants self-reported pain levels, but they could also discern between patients with no pain to mild pain and patients with moderate to severe pain. The predictive modeling even outperformed clinical markers such as heart rate and mean arterial pressure.