Cortisol as a Marker of Pain and Distress After Acute Musculoskeletal Trauma

The best available predictors of chronic pain development broadly encompass baseline metrics of cognition (ie, beliefs/expectations) about the trauma and resulting symptoms. In the context of musculoskeletal trauma, we have previously shown the Traumatic Injuries Distress Scale (TIDS) capable of risk-stratifying cohorts for chronic pain development. Here, we explore whether the physiological marker cortisol shows meaningful associations with cognitions predictive of pain outcomes.

Data for these cross-sectional analyses were drawn from an observational study that recruited 130 participants presenting to the hospital with pain related to a recent noncatastrophic Musculoskeletal trauma. Cortisol was measured from the participant's hair, saliva, and blood. In addition to pain and distress questionnaires, metadata such as age, sex, body mass index (BMI), adverse childhood events, pretrauma stress levels, and pre-existing physical/psychological comorbidities were collected.

We found no significant associations between cortisol levels and pain or distress in isolation. When stratified by person-level variables, associations were revealed with distress (TIDS) in young age and low pretrauma stress subgroups (hair cortisol) and low BMI (blood cortisol). Through hierarchical regression analysis, we found the "cortisol X age" or "cortisol X stress" interaction terms significantly improved TIDS prediction beyond either variable in isolation (Age: ∆ R2 =15.1%; pretrauma stress: ∆ R2 =9.1%).

Our findings suggest that while linear correlations between pain-related distress and cortisol may be overly simplistic, certain person-level variables such as age, pretrauma stress, and BMI are worthy of consideration for experimental design or confounder characterization in future studies of pain and distress following musculoskeletal injuries especially when "trait" (hair) cortisol is the predictor variable.