Background/Purpose: Although some individual foods and nutrients have been associated with knee osteoarthritis (OA) progression, the association between overall diet and OA progression is unknown. We aimed to examine the prospective association of major dietary patterns characterized by principal component analysis (PCA) with radiographic progression of knee OA.

Methods:  In the Osteoarthritis Initiative (OAI), 2741 participants (4302 knees) with modest to moderate radiographic knee OA in at least one knee (Kellgren and Lawrence [KL] grade of 1, 2 or 3) who had dietary data at baseline were followed 12, 24, 36 and 48 months. We defined radiographic knee OA progression for a specific knee as at least one full score increase of KL grade characterized by joint space narrowing and/or osteophytes from baseline to 48 months. Dietary intake was assessed with a Block Brief Food Frequency Questionnaire completed at baseline. Two dietary patterns were identified by PCA: the Prudent pattern characterized by high intakes of fruit/vegetables, legumes, whole grains, and fish; the Western pattern characterized by high intakes of red / processed meats, refined grains, and French fries. The Cox proportional hazards models using a discrete likelihood method were developed to calculate hazard ratios (HR) after adjusting for age, sex, race, body mass index (BMI), baseline KL, injury/surgery, NSAIDs use, physical activity, and total calorie intake.  We also used quantitative loss in joint space width (JSW) over time between the medial femur and tibia of the knee based on plain radiographs as the secondary measure of knee OA progression. Linear mixed models for repeated measures were used to assess the association between dietary patterns and JSW loss over time.  

Results:   Among 2741 participants (4302 knees) with OA at baseline, 721 knees had structural progression over 48 months. In multivariable adjusted models, a higher score for the Prudent dietary pattern was associated with a reduced risk of knee OA progression (p trend <0.01), while a higher score for the Western pattern was associated with an increased risk of progression (p trend <0.01) (Table). In addition, we observed a significant dose-response relationship between each dietary pattern score and adjusted mean JSW loss (Table). The observed associations attenuated after additionally adjusting for BMI.  

Conclusion: Following the Prudent dietary pattern may reduce the risk of knee OA progression, whereas following the Western pattern may be associated with an increased risk of progression. The associations were partially mediated by BMI. Replication of these novel findings in other prospective studies demonstrating that improvement of  dietary quality leads to delay in knee OA progression are needed. Key words: Dietary pattern, osteoarthritis progression, joint space width.