Abstract
BACKGROUND: Chronic low back pain (CLBP) is a prevalent condition associated with disability and increased health service usage. Understanding the interrelationship between central pain processing mechanisms, psychological factors, and functional outcomes in patients with CLBP may enhance their clinical assessment and treatment. This present study aimed to explore correlations between pain intensity and pain processing mechanisms (quantitative sensory testing [QST]), psychological factors (kinesiophobia, catastrophising, and anxiety), and functional outcomes (lumbar flexion-evoked pain thresholds and functional capacity) in individuals with CLBP. METHODS: In this exploratory study we recruited 50 patients with CLBP from a tertiary hospital in Valencia, Spain. Pain processing mechanisms were assessed using QST parameters (pressure pain threshold [PPT], temporal summation [TS], and conditioned pain modulation [CPM]). Psychological factors were measured through validated scales and functional outcomes were assessed via lumbar flexion-evoked pain threshold and the 1-minute sit-to-stand (STS60) test. Pearson correlation and stepwise regression analyses were used to examine associations and predictive relationships. RESULTS: Pain intensity was significantly associated with reduced PPT, low CPM, slower STS60 performance, and elevated kinesiophobia, catastrophising, and anxiety levels (p < 0.05). Regression analysis identified the PPT and STS60 results as significant predictors of pain intensity (AdjR(2) = 0.397, p < 0.001), accounting for 39.7% of the variation in lumbar pain. In turn, STS60 performance and catastrophising were significant predictors of kinesiophobia (AdjR(2) = 0.291, p < 0.001) accounting for 29.1% of its variation. CONCLUSION: Pain intensity in patients with CLBP correlates with central sensitisation, psychological distress, and functional limitations. PPT and STS60 may serve as valuable clinical indicators of pain severity and functional impairment, respectively. These findings support a multidimensional assessment framework for CLBP, integrating sensory, psychological, and functional factors to inform comprehensive treatment strategies.