Younger age is associated with greater pain expression among patients with knee or hip osteoarthritis scheduled for a joint arthroplasty

BACKGROUND: This study describes how patients with knee or hip osteoarthritis (OA), scheduled for arthroplasty, characterize their pain qualitatively and quantitatively and investigates whether differences exist in pain expression between younger and older patients, and between men and women. METHODS: One hundred eight patients scheduled for a joint arthroplasty completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) or Hip Disability and Osteoarthritis Outcome Score (HOOS) and a health-related quality of life question. Pain was assessed using the visual analogue scale (VAS), KOOS/HOOS and the Pain-o-Meter (POM) consisting of 12 sensory and 11 affective words (POM-Words). Frequency of analgesics use was assessed and preoperative radiographs were graded. ANOVA was used to test differences in pain expression with age (< 65 vs. ≥65 years), sex, and affected joint as independent factors. RESULTS: Patients < 65 years of age used more affective words (POM) and words with higher affective intensity (median scores 8 (3–39), 5.5 (2–27) respectively), than older patients, despite having less radiographically advanced OA. They also reported more symptoms (KOOS/HOOS) than older patients. However, pain ratings, as measured by VAS and KOOS/HOOS pain, did not differ between younger and older adults. Women reported more frequent analgesics use (45.7 and 26.5% respectively) and rated their pain higher than men (mean POM-VAS = 42 (SD 24) and 31 (SD 19); respectively). No differences existed between sexes for sensory or affective POM-Words, or radiographic grade of OA. With age and sex as independent factors, a significant difference between knee and hip OA remained for sensory POM-words intensity scores. CONCLUSIONS: Younger adults scheduled for arthroplasty expressed pain using more affective words and words with higher intensity and had less radiographically advanced OA than older adults. However, VAS and KOOS/HOOS pain subscales could not distinguish the difference in pain expression. Thus, the POM may be a valuable tool for assessment of pain.