Baylor College of Medicine / MEDVAMC Houston, Texas, United States
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Background/Purpose: Osteoarthritis (OA) is the most common form of arthritis, a condition associated with substantial disability. Radiographic severity of OA is associated with the presence or absence of frequent knee pain cross-sectionally. Our purpose was to test the prognostic potential of radiographs among knees without frequent pain by evaluating whether radiographic disease severity predicts frequent knee pain over time. Methods: This is a knee-based longitudinal study of participants of the Osteoarthritis Initiative (OAI). We only included knees that were free of frequent pain at the baseline visit. Posterior-Anterior semi-flexed knee radiographs were obtained at the baseline visit and scored for Kellgren-Lawrence (KL) grade (0-4). At the baseline and annual visits, participants reported whether they had knee-specific frequent pain using the question, of whether the participant has had had (right/left) knee pain, aching or stiffness on more than half the days of a month in the last 12 months?
We performed knee-based logistic regression analyses, using generalized estimating equations to account for correlation between knees within a person, where the independent variable was baseline KL grade and the outcome of interest was frequent knee pain at the 12-month visit. Analyses were repeated with outcome at the 48-month visit. Results: 6159 knees from 3714 participants were included in this study, 58% were female, mean age was 61.5 (9.2) years, mean body mass index was 28.3 (4.7) m2/kg. Conclusion: Radiographic disease severity, based on KL grades, is a prognostic biomarker for frequent knee pain among those without existing symptoms in as short as one year of follow-up. Radiographs could be a screening tool to identify those at high risk of developing frequent knee pain. This may be a useful strategy for testing potential therapies aimed at the preventing the onset of frequent knee pain.
