Central sensitization and functioning in patients with chronic low back pain: A cross-sectional and longitudinal...

Central sensitization (CS) is present in a subgroup of patients with chronic low back pain (CLBP). Studies on the relationship between CS and functioning have limited operationalizations of CS and functioning.

To determine whether CS was related to functioning in patients with CLBP (cross-sectional); and to determine whether changes in CS were related to changes in functioning (longitudinal).

An observational prospective cohort study with data collected at baseline and discharge of an interdisciplinary pain rehabilitation program was executed. CS indicators: CS Inventory part A (CSI-A), quantitative sensory testing (QST), root mean square of successive differences of heart-rate variability (RMSSD). Functioning measures: lifting capacity, physical functioning subscale of Rand36 (Rand36-PF), Work Ability Score (WAS), Pain Disability Index (PDI). Main analyses included correlation and multiple regression controlling for confounders; cross-sectional with baseline data and longitudinal with deltas (Δ).

76 patients with primary CLBP participated at baseline and 56 at discharge. Most associations were weak (cross-sectional r𝑝𝑎𝑟𝑡𝑖𝑎𝑙=-0.30-0.24; longitudinal r𝑝𝑎𝑟𝑡𝑖𝑎𝑙=-0.37-0.44). Cross-sectional multiple regression significant associations: mechanical pain threshold-QST and lifting capacity (r𝑝𝑎𝑟𝑡𝑖𝑎𝑙=-0.39), parasympathetic/vagal tone-RMSSD and physical functioning-Rand36-PF (r𝑝𝑎𝑟𝑡𝑖𝑎𝑙= 0.26). Longitudinal multiple regression significant associations: Δ parasympathetic/vagal tone-RMSSD and Δ lifting capacity (r𝑝𝑎𝑟𝑡𝑖𝑎𝑙= 0.48), ΔCSI-A and Δdisability-PDI (r𝑝𝑎𝑟𝑡𝑖𝑎𝑙= 0.36). Cross-sectional and longitudinal final regression models explained 24.0%-58.3% and 13.3%-38.0% of total variance.

CS was weakly related to functioning, and decreases in CS were weakly-moderately related to increases in functioning.