Comparing pain severity versus pain location in the MOBILIZE Boston study: chronic pain and lower extremity function.

BACKGROUND This study compared measures of chronic pain, for example, number of pain sites and overall pain severity, in relation to lower extremity function in the older population. METHODS Six hundred older adults (mean age 77.9 years, 64% female) were queried about presence of chronic pain. Number of pain sites was categorized as none, single site, multisite, or widespread. Pain severity was measured in quartiles of the Brief Pain Inventory pain severity subscale. Lower extremity function was assessed by the Short Physical Performance Battery (SPPB), a composite measure of gait speed, balance, and chair stands. RESULTS Many older persons reported multisite or widespread pain (40%). Increased pain sites and pain severity were associated with poorer SPPB performance after adjusting for age, sex, height, and weight. With further adjustment for education, comorbid conditions, and depressive symptoms, multisite pain (p < .001) and most severe pain (p < .05) were associated with poorer SPPB performance, but assessed together in the same model, only the association with multisite/widespread pain remained significant (p < .01). When specific joint pain sites were evaluated together, only knee pain was associated with lower SPPB score. Pain severity was independently associated with slower gait, pain location was associated with poorer balance, and chair stands performance was associated with both pain measures. CONCLUSIONS Although multisite pain rather than pain severity was more strongly associated with overall lower extremity function, differences emerged with specific SPPB subtests. Longitudinal studies are needed to understand risk for lower extremity function decline related to chronic pain characteristics in older adults.