Adherence to a blended intervention for patients with hip- and/or knee osteoarthritis, a mixed methods study

Aim: eHealth interventions can increase healthcare access, empower self-management and lower healthcare costs and are more effective for adherent patients. Adherence to eHealth interventions is well-documented, but knowledge on adherence to blended interventions that combine eHealth with face-to-face treatment is lacking. This study aims to explore which patient-, intervention- and environment-related are determinants of adherence to e-Exercise, a twelve-week blended physiotherapeutic intervention for patients with hip and/or knee osteoarthritis. Methods: A convergent mixed methods design was used. Negative binomial regression analysis was performed re-using quantitative data of a (cost)effectiveness trial on e-Exercise for independent variables. The number of weeks with an evaluated module were used to measure adherence. Patients that evaluated at least eight out of twelve weeks were considered adherent. Additionally, semi-structured interviews with patients on their adherence to e-Exercise were performed and analyzed. Results: Nineteen patients for which the program was not started were excluded. In total, 81.1% of the ninety patients that started were adherent. Adherence to e-Exercise could be predicted by education, osteoarthritis duration and the used recruitment strategy. During interviews, internet-skills, motivation, discipline, available time and physical ability were described as determinants of adherence. The intervention’s usability, flexibility, required time, persuasive design and added value, as well as environmental factors like participating in research and weather conditions can also influence adherence. Finally, participation in research and weather conditions influenced adherence. Conclusion: While some patient-related determinants were identified, the vast majority of the patients were adherent. The eHealth components’ usability, flexibility, time required, persuasive design and added value were linked to adherence, but the physiotherapist appears largely responsible for the high adherence rate. However, some physiotherapists didn’t start their patients’ program, illustrating that patient adherence can be further improved by optimally integrating the physiotherapist. Clinical Relevance: This is the first study to describe determinants of adherence to a blended physiotherapeutic intervention. Implementation of e-Exercise should focus on optimally integrating the eHealth component in the physiotherapists’ treatment regimen. Physiotherapists can offer e-Exercise to every indicated patient that is open to use it, but should consider offering patients with insufficient internet-skills and physical disabilities additional therapy