Background/Purpose: Metabolic syndrome (MetS) has been suggested as having a role in osteoarthritis (OA) pathogenesis. No study has assessed whether MetS and its components are associated with pain severity and number of painful sites (NPS) and their courses over time. We aimed to examine the association of MetS and its components with trajectories of pain severity and NPS in people with radiographic knee OA (ROA) over 10.7 years.

Methods: 1,099 participants (mean age 63 years) from a population-based older adult cohort study were recruited at baseline. 875, 768 and 563 participants attended years 2.6, 5.1 and 10.7 follow-up, respectively. Data were collected on demographic, psychological, lifestyle and comorbidities, blood pressure, glucose, triglycerides, and high-density lipoprotein (HDL) cholesterol. MetS was defined based on National Cholesterol Education Program-Adult Treatment Panel III criteria. ROA was assessed by X-ray. Knee pain was measured by Western Ontario and McMaster Universities Osteoarthritis Index pain questionnaire at each time-point. Presence/absence of pain at the neck, back, hands, shoulders, hips, knees and feet was collected by questionnaire at each time-point. Group-based trajectory modelling was applied to identify pain trajectories. Multi-nominal logistic regression was used for the analyses.

Results: 60% of participants had ROA and 32% had MetS at baseline. Three pain severity trajectories were identified in those with ROA: ‘Marginal pain’ (50%), ‘Mild pain’ (35%) and ‘Moderate pain’ (15%). Three NPS trajectories were identified: ‘Low NPS’ (10%), ‘Medium NPS’ (38%), and ‘High NPS’ (52%). In univariate analyses, MetS was associated with increased risk of both ‘Mild pain’ (relative risk: 1.47, 95%CI: 1.10−1.96) and ‘Moderate pain’ (2.22, 95%CI 1.54−3.20) relative to ‘Marginal pain’. It was also associated with increased risk of both ‘Medium NPS’ (2.25, 1.11 to 4.54) and ‘High NPS’ (3.36, 1.70−6.63) compared to ‘Low NPS’. In multivariable analyses, abdominal obesity was associated with increased risk of both ‘Mild pain’ (1.70, 1.17−2.49) and ‘Moderate pain’ (2.75, 1.63−4.64), and MetS and low HDL were associated with ‘Moderate pain’. Abdominal obesity was the only component associated with increased risk of both ‘Medium NPS’ (2.82, 1.39−5.70) and ‘High NPS’ (3.60, 1.79−7.24), and MetS was only associated with increased risk of ‘High NPS’. However, these associations became non-significant after further adjustment for body mass index, but hypertension became protective with ‘Mild pain’.

Conclusion: MetS is predominantly associated with trajectories of pain severity and number of painful sites through abdominal obesity, suggesting that weight loss is the most important way of controlling OA pain.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/metabolic-syndrome-and-trajectories-of-pain-severity-and-number-of-painful-sites-in-knee-osteoarthritis-data-from-a-10-7-year-prospective-study/