Group differences and associations between patient-reported outcomes and physical characteristics in chronic low back pain patients and healthy controls.

Background: Patients with chronic low back pain can exhibit altered slower gait, poor balance, and lower strength/power, and psychological dysfunctions such as pain catastrophizing and fear of movement. Few studies have investigated the relationships between physical and psychological dysfunctions. This study examined associations between patient-reported outcomes (pain interference, physical function, central sensitization, and kinesiophobia) and physical characteristics (gait, balance, and trunk sensorimotor characteristics).

Methods: Laboratory testing included a 4-m walk, balance, and trunk sensorimotor testing with 18 patients and 15 controls. Gait and balance were collected with inertial measurement units. Isokinetic dynamometry measured trunk sensorimotor characteristics. Patient-reported outcomes included PROMIS Pain Interference / Physical Function, Central Sensitization Inventory, and Tampa Scale of Kinesiophobia. Independent t-tests or Mann-Whitney U tests were used to compare between groups. Additionally, Spearman's rank correlation coefficient (r established associations between physical and psychological domains, and Fisher z-tests compared correlation coefficient values between groups (significance P < 0.05).

Findings: The patient group had worse tandem balance and all patient-reported outcomes (P < 0.05) while no group differences were observed in gait and trunk sensorimotor characteristics. There were significant correlations between worse central sensitization and poor tandem balance (r = 0.446-0.619, P < 0.05) and lower peak force and rate of force development (r = -0.429-0.702, P < 0.05).

Interpretation: Observed group differences in tandem balance agree with previous studies, indicating impaired proprioception. The current findings provide preliminary evidence that balance and trunk sensorimotor characteristics were significantly associated with patient-reported outcomes in patients. Early and period screening could help clinicians further categorize patients and develop objective treatment plans.