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

BACKGROUND: 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. OBJECTIVE: 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). METHODS: 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 ([Formula: see text]). RESULTS: 76 patients with primary CLBP participated at baseline and 56 at discharge. Most associations were weak (cross-sectional [Formula: see text] [Formula: see text] 0.30–0.24; longitudinal [Formula: see text] [Formula: see text] 0.37–0.44). Cross-sectional multiple regression significant associations: mechanical pain threshold-QST and lifting capacity ([Formula: see text] [Formula: see text] 0.39), parasympathetic/vagal tone-RMSSD and physical functioning–Rand36-PF ([Formula: see text] 0.26). Longitudinal multiple regression significant associations: [Formula: see text] parasympathetic/vagal tone-RMSSD and [Formula: see text] lifting capacity ([Formula: see text] 0.48), [Formula: see text] CSI-A and [Formula: see text] disability-PDI ([Formula: see text] 0.36). Cross-sectional and longitudinal final regression models explained 24.0%–58.3% and 13.3%–38.0% of total variance. CONCLUSION: CS was weakly related to functioning, and decreases in CS were weakly-moderately related to increases in functioning.