title: Outcome Expectations and Osteoarthritis: Association of Perceived Benefits of Exercise With Self-Efficacy and Depression.
abstract: Outcome expectancy is recognized as a determinant of exercise engagement and adherence. However, little is known about which factors influence outcome expectations for exercise among people with knee osteoarthritis (OA). This is the first study to examine the association of outcome expectations for exercise with demographic, physical, and psychosocial outcomes in individuals with knee OA.
  
  
  
  We performed a cross-sectional analysis of the baseline data from a randomized trial of tai chi versus physical therapy in participants with symptomatic knee OA. Knee pain was evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Outcome expectations for exercise, self-efficacy, depression, anxiety, stress, and social support were measured using standard instruments. Logistic regression models were utilized to determine associations with outcome expectations.
  
  
  
  There were 262 participants, with a mean age of 59.8 years and a mean body mass index of 32.1 kg/m2; 69.1% of the participants were female, 51.5% were white, the mean disease duration was 8.6 years, and the mean WOMAC knee pain and function scores were 260.8 and 906.8, respectively. Higher outcome expectations for exercise were associated with greater self-efficacy (odds ratio [OR] 1.25 [95% confidence interval (95% CI) 1.11-1.41]; P = 0.0004), as well as with fewer depressive symptoms (OR 0.84 for each 5-point increase [95% CI 0.73-0.97]; P = 0.01). Outcome expectancy was not significantly associated with sex, race, education, pain, function, radiographic severity, social support, anxiety, or stress.
  
  
  
  Our results suggest significant associations between outcome expectations for exercise and self-efficacy and depression. Future studies should examine how these relationships longitudinally affect long-term clinical outcomes of exercise-based treatment for knee OA.
authors.affiliation: Center for Integrative Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Marszalek
authors.affiliation: Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, and Tufts Clinical and Translational Science Institute, Tufts University, Boston, Massachusetts.
authors.forename: Lori Lyn
authors.initials: LL
authors.lastname: Price
authors.affiliation: Center for Integrative Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: William F
authors.initials: WF
authors.lastname: Harvey
authors.affiliation: Center for Integrative Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Driban
authors.affiliation: Center for Integrative Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Wang
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D003863:Depression / Q000175:diagnosis / Q000523:psychology*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D010147:Pain Measurement; D010349:Patient Compliance; D016032:Randomized Controlled Trials as Topic; D020377:Self Efficacy; D011795:Surveys and Questionnaires; D026302:Tai Ji; D013997:Time Factors; D016896:Treatment Outcome