title: Adherence to a web-based physical activity intervention for patients with knee and/or hip osteoarthritis: a mixed method study.
abstract: BACKGROUND
  Web-based interventions show promise in promoting a healthy lifestyle, but their effectiveness is hampered by high rates of nonusage. Predictors and reasons for (non)usage are not well known. Identifying which factors are related to usage contributes to the recognition of subgroups who benefit most from Web-based interventions and to the development of new strategies to increase usage.
  
  
  OBJECTIVE
  The aim of this mixed methods study was to explore patient, intervention, and study characteristics that facilitate or impede usage of a Web-based physical activity intervention for patients with knee and/or hip osteoarthritis.
  
  
  METHODS
  This study is part of a randomized controlled trial that investigated the effects of Web-based physical activity intervention. A total of 199 participants between 50-75 years of age with knee and/or hip osteoarthritis were randomly assigned to a Web-based intervention (n=100) or a waiting list (n=99). This mixed methods study used only data from the individuals allocated to the intervention group. Patients were defined as users if they completed at least 6 out of 9 modules. Logistic regression analyses with a stepwise backward selection procedure were executed to build a multivariate prediction usage model. For the qualitative part, semistructured interviews were conducted. Both inductive and deductive analyses were used to identify patterns in reported reasons for nonusage.
  
  
  RESULTS
  Of the 100 participants who received a password and username, 46 completed 6 modules or more. Multivariate regression analyses revealed that higher age (OR 0.94, P=.08) and the presence of a comorbidity (OR 0.33, P=.02) predicted nonusage. The sensitivity analysis indicated that the model was robust to changes in the usage parameter. Results from the interviews showed that a lack of personal guidance, insufficient motivation, presence of physical problems, and low mood were reasons for nonusage. In addition, the absence of human involvement was viewed as a disadvantage and it negatively impacted program usage. Factors that influenced usage positively were trust in the program, its reliability, functionality of the intervention, social support from family or friends, and commitment to the research team.
  
  
  CONCLUSIONS
  In this mixed methods study, we found patient, intervention, and study factors that were important in the usage and nonusage of a Web-based PA intervention for patients with knee and/or hip osteoarthritis. Although the self-guided components offer several advantages, particularly in relation to costs, reach, and access, we found that older patients and participants with a comorbid condition need a more personal approach. For these groups the integration of Web-based interventions in a health care environment seems to be promising.
authors.affiliation: Netherlands Institute for Health Services Research (NIVEL), Utrecht, Netherlands. d.bossen@nivel.nl.
authors.forename: Daniël
authors.initials: D
authors.lastname: Bossen
authors.forename: Michelle
authors.initials: M
authors.lastname: Buskermolen
authors.forename: Cindy
authors.initials: C
authors.lastname: Veenhof
authors.forename: Dinny
authors.initials: D
authors.lastname: de Bakker
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000368:Aged; D019983:Guideline Adherence; D006801:Humans; D020407:Internet; D008875:Middle Aged; D009043:Motor Activity; D015207:Osteoarthritis, Hip / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology*
keywords: Web-based intervention; adherence; mixed method study; usage