# Assessment of central pain sensitization in chronic low back pain and its utility in diagnosis and prediction of clinical severity

## TL;DR

This study shows that SREP, a dynamic pain indicator, can help distinguish chronic low back pain patients from healthy individuals, but it does not predict clinical severity.

## Contribution

The study introduces SREP as a novel method for detecting central pain sensitization in chronic low back pain.

## Key findings

- SREP effectively distinguished CLBP patients from healthy individuals with 66.3% accuracy.
- TSP was not able to differentiate between CLBP patients and healthy individuals.
- TSP, but not SREP, predicted clinical severity in CLBP patients.

## Abstract

Slowly repeated evoked pain (SREP) is a dynamic pain indicator useful in conditions involving central sensitization. This study evaluated SREP in patients with chronic low back pain (CLBP) and compared it to temporal summation of pain (TSP). The SREP protocol involved nine low-to-moderate painful pressure stimuli (5 s each, 30-s intervals) in 40 patients with CLBP and 40 healthy individuals. Clinical-psychological factors, pain threshold, tolerance, and TSP were assessed. Patients with CLBP showed increasing pain ratings to SREP (0.78 ± 1.05), while healthy individuals did not (−0.44 ± 1.10). No significant group differences were found in TSP, pain threshold and tolerance. SREP effectively distinguished patients with CLBP from healthy individuals (66.3% accuracy), with an optimal cut-off of 0.05 (sensitivity = 77.5%, specificity = 60%), while other pain tests did not. Usual and current pain, central sensitization-related symptoms, and catastrophizing correlated with TSP but not SREP. Sensitization to SREP distinguished patients with CLBP from healthy individuals while TSP did not provide discriminatory ability. However, SREP did not predict clinical severity of the patients, whereas TSP allowed for the prediction of clinical severity. Future development in the application of SREP protocol could help detect and assess the centralized pain component in CLBP.