Patients' and clinicians' experiences with stratified exercise therapy in knee osteoarthritis: a qualitative study.

Background: We have developed a model of stratified exercise therapy that distinguishes three knee osteoarthritis (OA) subgroups ('high muscle strength subgroup', 'low muscle strength subgroup', 'obesity subgroup'), which are provided subgroup-specific exercise therapy (supplemented by a dietary intervention for the 'obesity subgroup'). In a large clinical trial, this intervention was found to be no more effective than usual exercise therapy. The present qualitative study aimed to explore experiences from users of this intervention, in order to identify possible improvements.

Methods: Qualitative research design embedded within a cluster randomized controlled trial in a primary care setting. A random sample from the experimental arm (i.e., 15 patients, 11 physiotherapists and 5 dieticians) was interviewed on their experiences with receiving or applying the intervention. Qualitative data from these semi-structured interviews were thematically analysed.

Results: We identified four themes: one theme regarding the positive experiences with the intervention and three themes regarding perceived barriers. Although users from all 3 perspectives (patients, physiotherapists and dieticians) generally perceived the intervention as having added value, we also identified several barriers, especially for the 'obesity subgroup'. In this 'obesity subgroup', physiotherapists perceived obesity as difficult to address, dieticians reported that more consultations are needed to reach sustainable weight loss and both physiotherapists and dieticians reported a lack of interprofessional collaboration. In the 'high muscle strength subgroup', the low number of supervised sessions was perceived as a barrier by some patients and physiotherapists, but as a facilitator by others. A final theme addressed barriers to knee OA treatment in general, with lack of motivation as the most prominent of these.

Conclusion: Our qualitative study revealed a number of barriers to effective application of the stratified exercise therapy, especially for the 'obesity subgroup'. Based on these barriers, the intervention and its implementation could possibly be improved. Moreover, these barriers are likely to account at least partly for the lack of superiority over usual exercise therapy.

Trial Registration: The Netherlands National Trial Register (NTR): NL7463 (date of registration: 8 January 2019).