Preliminary characterization of age and chronic low back pain effects on multimodal pain sensitivity: a comparison study in older adults with and without chronic low back pain.

Though pain sensitivity impairments contribute to chronic pain in younger adults, it is unclear if pain hypersensitivity manifests with aging and is heightened in the geriatric chronic low back pain (CLBP) population. The cross-sectional study preliminarily addressed this gap by measuring pain sensitivity in older adults with CLBP (n=25) as well as pain-free sex-matched older (n=25) and younger adults (n=25). Pain sensitivity was quantified by 8 distinct measures that were subdivided as static (i.e., pressure pain thresholds, heat pain thresholds, fixed mechanical pain, and fixed cold pain) and dynamic pain sensitivity (i.e., mechanical temporal summation, thermal ramp and hold, heat pain aftersensations, and conditioned pain modulation). Test-retest reliability values for pain sensitivity ranged from moderate to excellent (ICCs≥0.500; p's<0.05). The main effect for group was significant (partial η2 =.413, p<0.001), revealing between-group differences in pain sensitivity on 5 out of 8 tests (p's≤0.043). Predominantly, both older adult groups demonstrated increased pain facilitation and decreased pain inhibition during dynamic pain sensitivity testing compared to pain-free younger adults (p's≤0.044). Despite qualitative differences, static and dynamic pain sensitivity responses were statistically similar between older adults with and without chronic LBP (p's>0.05). Findings suggest pain sensitivity can be reliably measured in older adults and that pain hypersensitivity develops with chronological aging, providing partial support for the theory that pain hypersensitivity may impact geriatric chronic pain populations. Further study is needed to more definitively parse out whether pain hypersensitivity is comparatively heightened in older adults with chronic LBP beyond the influence of chronological aging. PERSPECTIVE: This article establishes that surrogate measures of centrally mediated pain sensitization are heightened with aging. Impaired endogenous pain modulation may influence chronic pain development, maintenance, treatment efficacy, and/or ensuing disability, necessitating research to comprehensively characterize how pain hypersensitivity contributes to geriatric chronic pain conditions.