Central Sensitization and Pain Catastrophizing Are More Strongly Associated with Health-Related Quality of Life than Bioelectrical Impedance Analysis-Derived Body-Composition Measures in Patients with Chronic Low Back Pain

Background/Objectives: Chronic low back pain (LBP) is a multifactorial condition in which biological, psychological, and physical factors are associated with pain persistence and reduced health-related quality of life (HRQoL). Although central sensitization, pain catastrophizing, functional disability, and body composition have each been associated with CLBP, their relative contributions to HRQoL remain incompletely understood. This study investigated the relationships among these factors and identified factors associated with physical and mental HRQoL in multivariable analyses. Methods: In this cross-sectional observational study, 97 adults with CLBP undergoing rehabilitation were consecutively recruited from a tertiary rehabilitation department. Participants underwent standardized clinical evaluation, psychometric assessment using the Central Sensitization Inventory-9 (CSI-9), Pain Catastrophizing Scale (PCS), Roland–Morris Disability Questionnaire (RMDQ), and Italian Chronic Pain Classification (ICDS), whole-body bioelectrical impedance analysis (BIA), and HRQoL assessment using the 36-Item Short Form Health Survey (SF-36). Correlation analyses, group comparisons according to pain chronicity, and multivariable linear regression analyses were performed to evaluate factors associated with the SF-36 Physical Component Summary (SF-36 PCS) and SF-36 Mental Component Summary (SF-36 MCS) scores after adjustment for the variables included in the models. Results: Greater central sensitization, pain catastrophizing, and functional disability were associated with poorer HRQoL, whereas the evaluated BIA-derived body-composition measures showed weak or non-significant associations. Patients with higher degrees of pain chronicity demonstrated significantly higher central sensitization, pain catastrophizing, and disability, together with lower physical and mental HRQoL, but did not differ significantly in body composition. In multivariable analyses, central sensitization and pain catastrophizing remained associated with both SF-36 PCS and SF-36 MCS scores after adjustment for the other variables included in the models, whereas body composition parameters were not significantly associated with HRQoL. Conclusions: Psychological pain-related factors, particularly central sensitization and pain catastrophizing, are more strongly associated with HRQoL than the evaluated BIA-derived body-composition measures in patients with CLBP. Assessment of these factors may help inform patient stratification and personalized biopsychosocial rehabilitation planning; however, whether interventions specifically targeting them improve HRQoL requires prospective evaluation.