Onderzoek naar verbeteren van fysiotherapiebehandeling bij knieartrose

Rationale: Knee osteoarthritis (OA) is a highly heterogeneous disease, in which exercise therapy by a physical therapist (PT) is recommended as a first-step, conservative treatment. Nonetheless, the clinical effects of exercise therapy on knee pain and physical function are only modest, which may be attributed to a generic, ‘one-size-fits-all’ approach. Because of the large heterogeneity of knee OA with large differences between patients, a stratified approach in exercise therapy, meaning that patients are allocated to subgroups and receive a subgroup-specific intervention, may be superior over usual exercise therapy. Recently, we were able to identify clinically relevant subgroups of knee OA patients, developed a model of stratified exercise therapy based on these subgroups, and tested its feasibility in a pilot-study. Therefore, it is timely to evaluate the effectiveness and cost-effectiveness of stratified exercise therapy compared to usual (‘non-stratified’) care by PTs in a large-scale cluster randomized controlled trial (CRCT).



Objective: The present project aims to evaluate the effectiveness and cost-effectiveness of stratified exercise therapy, compared to usual care, in patients with knee OA treated by PTs in primary care.



Study design: A pragmatic, cluster randomized controlled trial (CRCT) with an economic and a process evaluation, comparing stratified exercise therapy with usual care by PTs in primary care. PT practices in a primary care setting (n=60, with 2 participating PTs per practice) will be randomized in a 1:2 ratio to provide the experimental or control intervention, respectively.



Study population: 408 eligible patients with diagnosed knee OA visiting a participating PT because of persisting knee complaints.



Intervention: The model of stratified exercise therapy for PTs consists of a stratification tool and subgroup-specific, protocolized exercise therapy. Based on the stratification tool, patients will be allocated to a ‘high muscle strength subgroup’, ‘low muscle strength subgroup’, or ‘obesity subgroup’. For the ‘obesity subgroup’, a dietary intervention by a dietician in primary care will be provided, in addition to the exercise therapy. The control intervention will be usual care from the PT.



Main study parameters/endpoints: Knee pain severity (NRS) and physical functioning (KOOS subscale daily living) will be primary outcome measures. Secondary outcome measures include global perceived effect (GPE), pain interference, fatigue, and knee instability (questionnaires), and upper leg muscle strength, body mass index (BMI), and waist circumference (physical tests). In addition, an economic evaluation (by patient-reported costs and quality-adjusted life years (QALYs)) and a process evaluation (by treatment registration forms) will be performed. Measurements will be performed at baseline, and 3 months (primary endpoint), 6 months (questionnaires only) and 12 months follow-up, with an additional cost questionnaire at 9 months.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness: All patients (from both treatment arms) will be treated by their own PT, with clinical effects and minimal risks to be expected. In the pilot-study (n=50), no adverse events occurred. The burden of the patients will be minimized to the time necessary for completing the questionnaires and tests.

Knee osteoarthritis (OA) is a highly heterogeneous disease, in which exercise therapy by a physical therapist (PT) is recommended as a first-step, conservative treatment. Nonetheless, the clinical effects of exercise therapy on knee pain and physical function are only modest, which may be attributed to a generic, ¡®one-size-fits-all¡¯ approach. Because of the large heterogeneity of knee OA with large differences between patients, a stratified approach in exercise therapy, meaning that patients are allocated to subgroups and receive a subgroup-specific intervention, may be superior over usual exercise therapy. Recently, we were able to identify clinically relevant subgroups of knee OA patients, developed a model of stratified exercise therapy based on these subgroups, and tested its feasibility in a pilot-study. Therefore, it is timely to evaluate the effectiveness and cost-effectiveness of stratified exercise therapy compared to usual (¡®non-stratified¡¯) care by PTs in a large-scale cluster randomized controlled trial (CRCT). The OCTOPUS-study aims to evaluate the effectiveness and cost-effectiveness of stratified exercise therapy, compared to usual care, in patients with knee OA treated by PTs in primary care.

Primary and secondary outcome measures will be assessed at baseline (t0) and 3 months (t3; primary endpoint), 6 months (t6) and 12 months follow-up (t12). In exception to this, the physical tests (muscle strength, BMI and waist circumference) will not be assessed at t6 and an additional economic evaluation will be assessed at 9 months follow-up (t9). Furthermore, process information on the content, intensity and volume of the intervention will be assessed through registration forms after each treatment sessions by the PT and dietician. Finally, qualitative information on treatment feasibility will be collected after the inclusion period through (semi-structured) interviews with ‘topic lists’ in a random sample of patients from both treatment arms (n=20), PTs from both treatment arms (n=10) and dieticians (n=5).

The experimental intervention will be a model of stratified exercise therapy for PTs. This model consists of a stratification tool and subgroup-specific, protocolized exercise therapy. Based on the stratification tool, patients will be allocated to a ‘high muscle strength subgroup’, ‘low muscle strength subgroup’, or ‘obesity subgroup’. Each of these subgroups will receive subgroup-specific, protocolized exercise therapy. For the ‘obesity subgroup’, a dietary intervention by a dietician in primary care will be provided, in addition to the exercise therapy.



The control intervention will be usual care from the PT.