Research Summary

Cortisol Levels Reflect Pain Severity in Emergency Care

Miranda Manier, BA

Key Highlights:

  • Cortisol levels in the prehospital setting significantly correlated with patients’ self-reported pain scores.
  • The correlation coefficient between cortisol and pain was high (r = 0.87; P < .001).
  • Cortisol showed excellent classification accuracy for moderate and severe pain (AUC = 0.837 and 0.981, respectively).
  • Cortisol may be a viable biomarker for objective pain assessment in emergency prehospital care.

In a large prospective observational study, investigators found that prehospital cortisol levels showed a strong correlation with self-reported pain scores, as measured by the numerical rating scale (NRS).

Pain evaluation remains a subjective and complex clinical challenge, particularly in the prehospital environment where rapid assessments are essential. While the NRS is commonly used, it relies on self-reporting, which may be unreliable or impossible in certain populations. Cortisol, a stress-related hormone, has long been associated with physiologic responses to pain, but its utility in prehospital settings had not been clearly defined. This study aimed to fill that gap by assessing the relationship between serum cortisol levels and NRS pain scores in patients undergoing emergency medical transport.

Researchers conducted a prospective study involving 1516 adult patients with acute medical conditions who were managed by Emergency Medical Services (EMS) and subsequently transported to the emergency departments of two tertiary care hospitals. Demographic information, vital signs, and blood samples were collected in the prehospital setting. Pain was evaluated using the NRS and categorized into four groups: pain-free (0), mild (1-3), moderate (4-6), and severe (≥7). Statistical analyses included correlation coefficients and area under the receiver operating characteristic (ROC) curve (AUC) to assess cortisol’s ability to classify pain levels.

The median patient age was 67 years, and 42.7% were female. Overall, 38.5% of patients reported no pain, while 34.6%, 16.1%, and 10.8% reported mild, moderate, and severe pain, respectively. Median cortisol concentration was 282 nmol/L, and the median NRS score was 1. A highly significant correlation was observed between cortisol levels and NRS pain scores (P < .001), with a correlation coefficient of 0.87. Cortisol levels varied significantly across the four NRS categories. The AUC values for cortisol’s classification performance were highest for severe (0.981; 95% CI, 0.970–0.991) and moderate pain (0.837; 95% CI, 0.803–0.872), while the AUC for mild pain was low (0.496), suggesting limited discriminatory power in this category.

“Cortisol levels show similar pain evaluation as NRS, with high-correlation for NRS pain categories, except for mild-pain,” the authors concluded. “Therefore, cortisol evaluation via the EMS could provide information regarding pain status.”

Reference:
López-Izquierdo R, Ingelmo-Astorga EA, Del Pozo Vegas C, et al. Association between blood cortisol levels and numerical rating scale in prehospital pain assessment. Commun Med (Lond). 2025;5(1):308. doi:10.1038/s43856-025-01020-4