Moderators of the effect of therapeutic exercise for knee and hip osteoarthritis: a systematic review and individual participant data meta-analysis

Moderators of the effect of therapeutic exercise for knee and hip osteoarthritis: a systematic review and individual participant data meta-analysis
https://www.thelancet.com/journals/lanrhe/article/PIIS2665-9913(23)00122-4/fulltext

Methods
We did a systematic review and individual participant data (IPD) meta-analysis of randomised controlled trials comparing therapeutic exercise with non-exercise controls in people with knee osteoathritis, hip osteoarthritis, or both. We searched ten databases from March 1, 2012, to Feb 25, 2019, for randomised controlled trials comparing the effects of exercise with non-exercise or other exercise controls on pain and physical function outcomes among people with knee osteoarthritis, hip osteoarthritis, or both. IPD were requested from leads of all eligible randomised controlled trials. 12 potential moderators of interest were explored to ascertain whether they were associated with short-term (12 weeks), medium-term (6 months), and long-term (12 months) effects of exercise on self-reported pain and physical function, in comparison with non-exercise controls. Overall intervention effects were also summarised. This study is prospectively registered on PROSPERO (CRD42017054049).

Findings
Of 91 eligible randomised controlled trials that compared exercise with non-exercise controls, IPD from 31 randomised controlled trials (n=4241 participants) were included in the meta-analysis. Randomised controlled trials included participants with knee osteoarthritis (18 [58%] of 31 trials), hip osteoarthritis (six [19%]), or both (seven [23%]) and tested heterogeneous exercise interventions versus heterogeneous non-exercise controls, with variable risk of bias. Summary meta-analysis results showed that, on average, compared with non-exercise controls, therapeutic exercise reduced pain on a standardised 0–100 scale (with 100 corresponding to worst pain), with a difference of –6·36 points (95% CI –8·45 to –4·27, borrowing of strength [BoS] 10·3%, between-study variance [τ2] 21·6) in the short term, –3·77 points (–5·97 to –1·57, BoS 30·0%, τ2 14·4) in the medium term, and –3·43 points (–5·18 to –1·69, BoS 31·7%, τ2 4·5) in the long term. Therapeutic exercise also improved physical function on a standardised 0–100 scale (with 100 corresponding to worst physical function), with a difference of –4·46 points in the short term (95% CI –5·95 to –2·98, BoS 10·5%, τ2 10·1), –2·71 points in the medium term (–4·63 to –0·78, BoS 33·6%, τ2 11·9), and –3·39 points in the long term (–4·97 to –1·81, BoS 34·1%, τ2 6·4). Baseline pain and physical function moderated the effect of exercise on pain and physical function outcomes. Those with higher self-reported pain and physical function scores at baseline (ie, poorer physical function) generally benefited more than those with lower self-reported pain and physical function scores at baseline, with the evidence most certain in the short term (12 weeks).

Interpretation
There was evidence of a small, positive overall effect of therapeutic exercise on pain and physical function compared with non-exercise controls. However, this effect is of questionable clinical importance, particularly in the medium and long term. As individuals with higher pain severity and poorer physical function at baseline benefited more than those with lower pain severity and better physical function at baseline, targeting individuals with higher levels of osteoarthritis-related pain and disability for therapeutic exercise might be of merit.

 

Whatever one meta analysis or systematic review may do better than others, since others have boasted of significant benefits and established this claim as a well-known fact, in this case it was a full reanalysis using individual patient data, and it follows the usual pattern where individual trials and reviews that take them at their word massively overinflate what are generic and mostly unnoticeable benefits to the individual patient.

The pattern continues to be that although exercise does have generic overall benefits to health, ones that may easily be confused in a backward way, where healthier people are better able to exercise, specific benefits are almost always non-existent or, at best, barely noticeable. The short-term benefits here are on the order of 6 point out of 100, and half of that medium and long term. This is unnoticeable and likely mostly random noise. About the same as pretending to turn up the thermostat without actually touching it and hearing "oh yeah much better thank you".

Oddly enough, they still recommend that it "might be of merit", without considering that it also might not be, thus wasting scarce resources for clinicians and time and energy for patients. Which seems to suggest a pathological inability to unhook from a prior position anchored by dishonest or misleading reporting of past biased studies. Medical evidence in particular seems to suffer from an extreme case of bullshit asymmetry.

Bit suspicious that they speak of controlled trials when none really are, but that's evidence-based medicine for you.

About the most accurate thing that can be said of exercise as a medical treatment is that it is a good treatment for lack of exercise, and not much else.

Some discussion, where I noticed this review: https://www.painscience.com/blog/exercise-for-arthritis-is-underwhelming.html.

 

I also find notable that IIRC one of the things that got dropped by Cochrane is the IPD review of PACE data. Likely because it would end up the same as this: bunk.