Title: Physical Activity in Adults With Knee Osteoarthritis
Description: Purpose: This dissertation has two primary aims; 1) to better understand how various physical, psychological, and general health factors influence physical activity (PA) and 2) to better understand different clinical phenotypes in people with knee osteoarthritis (OA) and functional outcomes, including PA. Methods: This dissertation utilizes data from the 48-month follow up of the Osteoarthritis Initiative, an observational longitudinal study of 4,796 participants examining onset and progression of knee OA in community dwelling adults between the age of 45-79. For the first study: 403 participants in a subset of participants using accelerometer- derived PA data, were analyzed for significant correlates of total PA time to estimate total PA using a linear regression model with bootstrapped standard errors. The second study includes data from 1,057 participants to perform a K-Mean Cluster analysis using body mass index, depressive symptoms, strength and radiographic evidence. One Way Analysis of Variance analysis and a Tukey’s post-hoc test was utilized to compare clinical outcomes between clusters including PA, function and pain.

Results: In our first study: Over three-quarters of our sample did not meet the recommended volumes of PA. Negative associations were noted between higher BMI and total PA, comorbid conditions and total PA, and increasing age and total PA. A positive association was noted between diverting attention as a coping strategy and higher volumes of PA. In our second study: The cluster analysis identified 5 clinical phenotypes. Significant differences were noted between phenotypic groups in all clinical outcomes measured. Conclusion: Older adults with knee OA are not meeting recommendations for total PA, which can improve function and attenuate the effects of functional decline and disability. Four major factors were associated with total PA levels in a population with mild to moderate knee OA: co-morbidities, age, BMI, and the diverting attention coping strategy. In our second study, we identified five phenotypes of individuals with knee osteoarthritis and revealed differential clinical outcomes based on phenotypes.

Understanding clinical differences between phenotypes may enable us to efficiently and effectively target our interventions to optimize PA and functional outcomes in people with knee osteoarthritis.