Objective: To investigate determinants of the onset and progression of knee pain in a population-based sample of people aged > or = 50 yrs.
Methods: Prospective cohort study of 2982 people registered with three general practices in North Staffordshire, UK. Using questionnaire surveys at baseline and 3 yrs, demographic, knee-related and general health factors were assessed for their relationship with onset of new knee pain, and progression from non-severe to severe knee pain.
Results: Response rates were 77% (baseline) and 75% (follow-up). Baseline factors significantly associated with onset of knee pain were knee injury [odds ratio (OR) 1.6, 95% CI 1.2, 2.2], depression (OR 1.4, 95% CI 1.1, 1.8), widespread pain (OR 1.5, 95% CI 1.1, 1.9 compared with no pain) and younger age. Onset of severe knee pain was associated most strongly with obesity (OR 2.9, 95% CI 1.7, 5.1) and physical limitations (OR 2.5, 95% CI 1.5, 4.1), and with widespread pain, older age, female gender and comorbidity. The strongest independent predictors of progression from non-severe to severe knee pain were chronicity (OR 3.1, 95% CI 2.1, 4.6), previous use of health care (OR 2.2, 95% CI 1.5, 3.3) and obesity (OR 2.1, 95% CI 1.2, 3.6).
Conclusion: In addition to a focus on obesity, there is potential for primary prevention of knee pain by tackling knee injuries and treating depression. Other factors are likely to determine whether the knee pain then progresses. An area for future research is the ineffectiveness of current health care in halting or reversing progression of knee pain at a population level.