Background/Purpose: Participation restrictions, common among people with knee osteoarthritis (OA), may be due to psychological factors. Many people with OA experience chronic pain, which can alter levels of positive and negative affect. Positive affect consists of emotional vitality and optimism, whereas negative affect is defined by unpleasant engagement or distress. Positive and negative affect may impact participation restriction over time; however, little is known of their long-term effects. We investigated the risk of incident participation restriction over 84 months with positive and negative affect among adults with or at risk of knee OA.

Methods: Data are from the Multicenter Osteoarthritis Study (MOST). Participants with participation restriction at baseline or who underwent total knee replacement during the 84 months were excluded. Participation restriction was measured using the Instrumental Role Limitation subscale of the Late Life Disability Index at 0, 30, 60, and 84 months. The Center for Epidemiological Studies Depression Scale was used to measure positive and negative affect at baseline. Scale values were dichotomized at the median to create high and low positive and negative affect groups. The risks of incident participation restriction over 84 months due to low positive affect, high negative affect, and combinations of low and high positive and negative affect were calculated in binomial regression analyses, adjusting for demographic factors, disease factors, and function. We tested the interaction between low positive and high negative affect.

Results: Of the 1810 participants at baseline, 470 (26%) (m=62.1 years, 56% female) had incident participation restriction over 84 months. In adjusted analyses, participants with low positive affect had 20% greater risk of incident participation restriction, and participants with high negative affect had 50% greater risk (Table 1). In the combination analysis, participants with both low positive affect and high negative affect had the highest adjusted risk of incident participation restriction [RR=1.8] compared to other combinations of positive and negative affect, but the interaction between positive and negative affect was not significant.

Conclusion: People with or at risk of knee OA with low positive and high negative affect are at increased risk of participation restrictions over time and efforts aimed at preventing participation restriction in this population should consider these psychological profiles.