Background
The effectiveness of exercise therapy for knee osteoarthritis (OA) is well established. Cochrane reviews have reported moderate, but statistically significant and clinically relevant post-treatment effects in favor of exercise therapy concerning pain reduction and increase in function. However, these studies have all been performed in populations with well-established knee OA, with symptom durations mostly for several years. When chronic pain already has developed and structural changes in the joint and disability has become severe, an active lifestyle and exercising has become more difficult, and the surgical replacement of the joint might seem the easy way out. There is an increasing emphasis in the literature on identifying and initiating treatment of OA in the early phases of the disease as this might be much more effective, because incidence and socioeconomic impact of OA is considerable and growing. Early interventions may prevent progression of the disease, the development of chronic pain and more severe disability and thereby partly prevent socioeconomic impact of OA. Defining relevant outcome measures when assessing such early stage treatment is challenging. Therefore, with this study we will investigate the magnitude of the effect of exercise therapy, compared to usual care, in patients with early-stage knee OA on pain and function after 3 months, and 12 months follow-up. We would like to use this information, together with an ongoing pilot study, for a future large-scale cost-effectiveness study.
This study aims to investigate whether duration of knee symptoms (as a measure of stage of OA) will influence the magnitude of the effect of exercise therapy compared to non-exercise controls on pain and physical function after 3 months, and 12 months follow-up.
Methods
We will make use of IPD data collected by STEER OA, a project within the OA Trial Bank.
For the current study purpose, studies (and consequently participants) fulfilling the following criteria will be selected from the OA Trial Bank:
- Study population: adults aged ≥ 45 years with knee OA, with a symptom duration < 12 months (and <24 months)
- Intervention: any land-based or water-based therapeutic exercise intervention regardless of content, duration, frequency or intensity
- Control: no exercise control group
- Outcome measure: Any self-reported pain and/or physical function at short- (closest to 3-months) or longer-term (closest to 12-months) follow-up
- Symptom duration: Measurement of symptom duration (continuous or categorized) and minimally including a sample (n>1) of participants with a symptom duration ≤ 1 year
We will describe trial-level and participant-level characteristics (for baseline variables and outcomes) of included studies.
All participant- level data from RCTs will be analysed in a single step to determine the treatment effect by considering both study-level and individual-level covariates in the multilevel regression model. To estimate the interaction effect (i.e., the interaction term pain or physical function x duration of symptoms) a one-stage multilevel regression model will be applied.
Status
Ongoing. Manuscript in preparation phase.