Objectives: The study aimed to compare the psychological and physical characteristics of older adults with knee osteoarthritis (OA) vs those of adults with chronic low back pain (CLBP) and to identify psychological and physical predictors of function as measured by gait speed.
Design: Secondary data analysis.
Method and patients: Eighty-eight older adults with advanced knee OA and 200 with CLBP who had participated in separate randomized controlled trials were selected for this study.
Measures: Inclusion criteria for both trials included age > or =65 and pain of at least moderate intensity that occurred daily or almost every day for at least the previous 3 months. Psychological constructs (catastrophizing, fear avoidance, self-efficacy, depression, affective distress) and physical measures (comorbid medical conditions, pain duration, pain severity, pain related interference, self-rated health) were obtained.
Results: Subjects with CLBP had slower gait (0.88 m/s vs 0.96 m/s, P = 0.002) and more comorbid conditions than subjects with knee pain (mean 3.36 vs 1.97, P < 0.001). All the psychological measures were significantly worse in the CLBP group except the Multidimensional Pain Inventory-Affective Distress score. Self-efficacy, pain severity, and medical comorbidity burden were associated with slower gait regardless of the location of the pain.
Conclusions: Older adults with chronic pain may have distinct psychological and physical profiles that differentially impact gait speed. These findings suggest that not all pain conditions are the same in their psychological and physical characteristics and may need to be taken into consideration when developing treatment plans.