Pain descriptors and determinants of pain sensitivity in knee osteoarthritis: a community-based cross-sectional study

OBJECTIVES: The aim was to explore pain characteristics in individuals with knee OA (KOA), to compare pain sensitivity across individuals with KOA, individuals with chronic back pain (CBP) and pain-free individuals (NP) and to examine the relationship between clinical characteristics and pain sensitivity and between pain characteristics and pain sensitivity in KOA. METHODS: We carried out a cross-sectional, community-based online survey. Two data sets were combined, consisting of Dutch individuals ≥40 years of age, who were experiencing chronic knee pain (KOA, n = 445), chronic back pain (CBP, n = 504) or no pain (NP, n = 256). Demographic and clinical characteristics, global health, physical activity/exercise and pain characteristics, including intensity, spreading, duration, quality (short-form McGill pain questionnaire) and sensitivity (pain sensitivity questionnaire), were assessed. Differences between (sub)groups were examined using analyses of variance or χ(2) tests. Regression analyses were performed to examine determinants of pain sensitivity in the KOA group. RESULTS: The quality of pain was most commonly described as aching, tender and tiring–exhausting. Overall, the KOA group had higher levels of pain sensitivity compared with the NP group, but lower levels than the CBP group. Univariately, pain intensity, its variability and spreading, global health, exercise and having co-morbidities were weakly related to pain sensitivity (standardized β: 0.12–0.27). Symptom duration was not related to pain sensitivity. Older age, higher levels of continuous pain, lower levels of global health, and exercise contributed uniquely, albeit modestly, to pain sensitivity (P < 0.05). CONCLUSION: Continuous pain, such as aching and tenderness, in combination with decreased physical activity might be indicative for a subgroup of individuals at risk for pain sensitivity and, ultimately, poor treatment outcomes.